cover

FOR MY PARENTS, MILTON AND GRACE HANGEN WILKES, AND FOR OUR CHILDREN AND THEIR FAMILIES: MARY GRACE, ANTHONY, AND NICHOLAS; GREG, TISH, AND ANSEL.

Mention of specific companies, organizations, or authorities in this book does not imply endorsement by the author or publisher, nor does mention of specific companies, organizations, or authorities imply that they endorse this book, its author, or the publisher. Internet addresses and phone numbers given in this book were accurate at the time it went to press.

This book was previously published as The New Seed-Starters Handbook by Rodale in 1988.

Illustrations by Frank Fetz

Photographs by Alison Miksch and Rodale Images

Book design by Joanna Williams

Library of Congress Cataloging-in-Publication Data is on file with the publisher.

ISBN 978–1–63565–104–1 paperback
ISBN 978-1-63565-105-8 e-book

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CONTENTS

Acknowledgments

Introduction

Editor’s Introduction to the Second Edition

SECTION ONE: STARTING SEEDS INDOORS

1Why Start Your Own Plants from Seeds?

2First the Seeds

3Choose Your Medium

4Choose Your Containers

5Light

6Sowing Seeds Indoors

7Germination

8What Seedlings Need

9Transplanting into New Containers

10Growing On

11Possible Problems

SECTION TWO: MOVING PLANTS OUTDOORS

12Soil Preparation

13Mapping Out the Garden

14The Garden Diary

15Hardening Off

16The Art of Planting Out

17Caring for Young Transplants

18Direct Seeding

19Foliar Fertilizers

20The Fall Garden

21Insect and Animal Pests

22Planting Seeds with Children

SECTION THREE: GROWING UNDER COVER

23Cold Frames and Other Protective Structures

24Starting Seedlings in the Greenhouse

25Growing Vegetables under Cover

SECTION FOUR: SEEDS: SAVING, STORING, AND MORE

26Why Save Seeds?

27How Seeds Are Formed

28Choosing Seeds to Save

29Collecting and Preparing Seeds

30Storing Seeds

31Seed Banks

32Viability of Seeds

33Seed-Saving Tips for Specific Plants

34Further Challenges

SECTION FIVE: ENCYCLOPEDIA OF PLANTS TO GROW FROM SEED

35Growing Garden Vegetables and Fruits from Seed

36Growing Herbs from Seed

37Growing Garden Flowers from Seed

38Growing Wildflowers from Seed

39Growing Trees and Shrubs from Seed

Sources for Seeds and Organic Garden Supplies

Glossary

Recommended Reading

ACKNOWLEDGMENTS

In referring to our debt to those who have gone before us, a wise man once said, “We stand on the shoulders of giants.” This is especially true in gardening, where we have been both enlightened by the experiments of learned men and supported by the faithful efforts of obscure dirt gardeners who have saved and selected seed and cared for the soil over the centuries.

In preparing this book, I received generous help—in the form of correspondence and printed matter—from Dr. R. J. Downs, Phytotron Director at the North Carolina State University at Raleigh; Dr. Robert F. Fletcher, Extension Specialist in Vegetable Crops at Penn State University; Dr. O. A. Lorenz, Chairman, Department of Vegetable Crops, University of California at Davis; Dr. Raymond Sheldrake, Professor of Vegetable Crops at Cornell University; Dr. H. Garrison Wilkes, Botany Department, Boston Harbor Campus of the University of Massachusetts; Dr. Jay S. Koths, Department of Plant Science, University of Connecticut; Dr. Betty Ransom Atwater, Director, Ransom Seed Laboratory, Santa Barbara, California; and Richard Grazzini, Manager of the H. G. German Seed Co., Smethport, Pennsylvania. Dr. H. Garrison Wilkes, Dr. J. F. Harrington, and Dr. James Edward Knott have kindly permitted me to quote from their work.

In addition, Dr. R. Gregory Plimpton of Atlantic and Pacific Research, Inc., has supplied me with much helpful information. Kent Whealy, originator of the Seed Savers Exchange, Forest Shomer, Director of the Abundant Life Seed Foundation, and Lawrence Hills of the Henry Doubleday Research Foundation have answered my inquiries in a spirit of kind cooperation and allowed me to quote from their writings. Articles by Dr. Jeffrey McCormack and Dr. Mark Widrlechner, published in Seed Savers Exchange Handbooks, have been very helpful.

Also, visits to the following growers were especially helpful: Bertha Reppert, Rosemary House, Mechanicsburg, Pennsylvania; Fairman and Kate Jayne, Sandy Mush Herb Nursery, Leicester, North Carolina; Cyrus Hyde, Well-Sweep Herb Farm, Port Murray, New Jersey; Janet Urban, Botanist, Bowman’s Hill Wildflower Preserve, Washington Crossing, Pennsylvania; and Bob Hyland, Education Director, Longwood Gardens, Kennett Square, Pennsylvania.

In addition, I learned much from phone conversations with Roger Kline, Extension Associate, Department of Vegetable Crops, Cornell University; Dr. John Gerber, University of Illinois; Dr. Jim Austin, Park Seed Co.; Pam Dwiggins, Research Botanist, National Wildflower Research Center, Austin, Texas; Dr. Arthur O. Tucker, Delaware State College; Greg Edinger, Naturalist at Bowman’s State Hill Wildflower Preserve, Washington Crossing, Pennsylvania; Rob Johnston of Johnny’s Selected Seeds, Albion, Maine; Dick Meiners of Pinetree Garden Seeds, Gloucester, Maine; Colleen Armstrong of The New Alchemy Institute, East Falmouth, Massachusetts; and Shepherd Ogden of Cook’s Garden Seed Company, Londonderry, Vermont.

My editor, Claire Kowalchik, always had the reader in mind. I’m ever so grateful for her careful questions and perceptive suggestions, which have helped immeasurably to make The New Seed-Starters Handbook a better book than the original.

I’m grateful, too, to my husband and children, who good-naturedly endure my absentmindedness when I am “with book.” Special thanks to my son, Greg (who now has his own family garden), for his perseverance in typing the whole much-spliced and much-corrected manuscript of the original edition.

INTRODUCTION

Since 1957, when we tried (and failed!) to grow radishes in a window box outside our third-floor apartment in Philadelphia, my husband, Mike, and I have been learning about growing vegetables. We got off to a slow start. I had only vague memories of the Victory Garden my parents grew for a few years in our New England backyard, and an insistent yearning to begin a garden of my own. Mike had grown up on home-raised vegetables—a surprisingly limited variety of them, though, mostly grown from seed his mother had carefully saved from one harvest to the next: cabbage, potatoes, beans, carrots, beets, dill, cucumbers, and sunflowers. Later, during a stay in Germany, he had taken a course in gardening at a free university of sorts. Mike wanted a garden, too.

When we moved into our first house, we bought digging forks and shovels almost before the ink was dry on the deed. We started that first year with tomatoes and beans and many flowers. It took us several years to progress to planting a garden that we could eat from all summer, but by 1970 our vegetable garden was carrying us year round. Today we hardly ever buy a vegetable. Our year-round supply of vegetables is due in large part to starting seeds early indoors and making continuous outdoor plantings of varieties of food chosen for quality and ease of storage.

Along the way, we’ve learned a lot about how and when to start different vegetables. Trial and error has helped. Older relatives and neighbors have been generous with advice and lore, and we never start a new gardening year without thinking fondly of our different mentors and how much they have given us over the years. Reading about gardens and gardening, seeds, plants, soil, and insects has given us a framework that often supports relationships between what we’ve observed and what we’ve been told. Mostly, though, we’ve muddled along, taking longer than it now seems we should have to see and use the full potential of a piece of ground and a packet of seeds.

That’s why I decided to write the first edition of The Seed-Starters Handbook—to help other gardeners make that jump from dabbling to self-sufficiency sooner and more easily than we did. At the same time, I hoped that experienced gardeners would find in it some insight into possibilities never considered, into alternatives and experiments in areas of gardening where the final word has yet to be written.

You know how it is when you put the phone down. You then remember all the other things you had intended to say. So it has been with this book. From the time the first edition was published, I’ve wished that I had included more about growing other garden flowers and wild plants from seed. In the ten years since I sent off that first manuscript, I’ve visited many gardens, asked a lot of questions, talked to numerous researchers, tried growing many new kinds of seeds, and read thousands of pages of gardening research, lore, and advice. Some of my learning grew out of my failures—with stubbornly dormant linden tree seeds, light-seeking scarlet sage seeds, and wildflower seeds that wouldn’t germinate without prechilling.

The result is The New Seed-Starters Handbook, which contains new sections that detail the principles and techniques for starting garden flowers, wildflowers, herbs, trees, and shrubs from seed. This material has been combined with the chapter from the first edition on growing vegetables and garden fruits from seed to create a handy encyclopedia section. No book of this size can include every possible plant in each of these categories, but I’ve tried to give you a selection of the best. Although this is a handbook, not a textbook, I’ve included Latin names for the plants under discussion, just so we’re all sure we’re talking about the same plant, and for your convenience in ordering seeds. Common names are charming but often vary locally. Latin names are accurate worldwide.

Apart from the encyclopedia section and several additional chapters, the other new material in the book has been inserted into the existing text via new words, paragraphs, pages, and sections. These additions and revisions represent an eight-month distilling process during which I evaluated and interpreted a whole file of new material accumulated since the day The Seed-Starters Handbook was published. Not a chapter remains untouched. To be honest, gardening friends, rechecking all the facts, summarizing old material, adding newly discovered findings, and writing new chapters has been more difficult than writing the original manuscript. I’m hugely relieved that it is done, but also delighted to have had the chance to improve my original work.

Consider this book a manual of procedures, giving you the step-by-step how and when of various planting techniques. Look, too, in every chapter, for the principles on which these techniques are based, and count on finding at least a few open-ended questions that might challenge old suppositions or suggest new growing frontiers.

There’s no one right way to do most of these things, you know. A good many workable options are open to you in planting seeds. I’ve tried to suggest the range of possibilities. The choice is up to you.

Let this book be smudged. Let it be marked. It’s meant to be used. I hope it will make a difference in your garden, and ultimately, on your table.

Once again, I wish you joy in planting seeds. The seed-starter works, always, at the edge of a mystery. Though we may take it for granted, we are part of that mystery, along with the fragility, the resilience, the dependability of the green world. Happy planting!

EDITOR’S INTRODUCTION TO THE SECOND EDITION

When I was asked to update Nancy Bubel’s classic book, I was honored to have the opportunity to help make one of my favorite go-to references available to new generations of gardeners. I have kept Nancy’s inimitable voice intact as much as possible while focusing more on the needs of today’s busy gardeners and smaller families, and adding some of the many wonderful tools and resources that have become available to organic gardeners since the first edition of this book hit the presses in 1988.

Happy seeding!

—Jean Nick

SECTION ONE

STARTING SEEDS INDOORS

To own a bit of ground, to scratch it with a hoe, to plant seeds and watch the renewal of life—this is the most commonest delight of the race, the most satisfactory thing a man can do.

—Charles Dudley Warner

WHY START YOUR OWN PLANTS FROM SEEDS?

Security and adventure might be considered opposites in some situations, but the gardener who raises plants from seed can experience both. Security—that confidence in the future that springs from one’s own ability, forethought, and preparation—and adventure—the soaring sense of “anything is possible” and “there are so many interesting things to try”—are well known to those who grow new varieties, experiment with new methods, and save their own seeds.

Skill in raising vegetable plants from seed is the very cornerstone of gardening independence. Choice of seeds and careful handling can bring you not only earlier harvests but also better vegetables. You can select varieties of food known to keep or process well so that the winter season, for which we gardeners are always planning, will be a time of abundance. Likewise, good eating will be yours all summer long from the selection of fresh vegetables you’ve planted for their superior quality.

THE REASONS

I suspect that I’d continue to raise my own seedlings even without a good excuse, because I enjoy the process. But when I stop to think about it, I realize that there are all kinds of good reasons for growing one’s own plants from seed.

Earlier harvests. You can get a much earlier start in the garden, and therefore put fresh food on the table sooner, when you’ve grown cabbage, tomato, eggplant, and pepper plants indoors for setting out when weather mellows. The sooner you can begin picking from your garden, the greater your yield for the year.

Greater variety. Varieties of plants offered by commercial seedling vendors represent but a tiny fraction of the possibilities open to you as a gardener. Buying started plants severely limits your options for raising vegetables of special flavor, insect or disease resistance, or extra nutritional value. If, for example, you want to grow late-blight-resistant tomatoes such as ‘Plum Regal’, ‘Mountain Magic’, and ‘Mountain Merit’, you’ll have to start with seeds. Looking for special gourmet foods like globe artichokes, watercress, or Japanese melons? It’s back to the seed catalogs. Peppers that are hot, but not too hot? Start your own Hungarian wax plants. Delicious, mild, sweet ‘Golden Acre’ or ‘Glory of Enkhuizen’ cabbage? You need to start those with seeds.

Stronger seedlings. Seedlings you’ve grown yourself can be super seedlings. If you do all the right things at the right times, you’ll have the best that can be grown, and you’ll know that your plants have well-developed roots growing in good soil that hasn’t been hyped with chemicals. You can even plant organically raised seeds in organic seed-starting mix to give your plants an extra start on excellence.

Healthier seedlings. By raising your own plants, you minimize the chance of introducing soilborne diseases to your garden. Clubroots and yellows that affect cabbage, along with anthracnose, tobacco mosaic, and wilt, are some examples of plant diseases you may avoid importing if you grow your own. Of course, you must use uncontaminated seed-starting mix and, in the case of mosaic in pepper, eggplant, and tomato seedlings, avoid handling tobacco around the plants.

Cost saving. You’ll save money. For the price of a dozen greenhouse tomato plants, you can buy a couple of seed packets—each of which will give you plants to share or to sell, or extra seeds to save for the following year. But because so many interesting plants can be grown from seed, once you start raising seedlings, you might find that you tend to put some of that saved money back into seeds of other kinds. Since you’re likely to eat even better as a result, you may well consider that you’re still far ahead.

Satisfaction. Creative satisfaction ought to count for something, too. From settling a well-chosen seedling in a pot of its own carefully prepared seed-starting mix and watching it grow greener, sturdier, and leafier, to picking and eating the peppers, eggplant, or other nutritious food the mature plant finally bears, you’ve been involved all the way. You can see that your skillful care has made a difference.

Enjoyment. At the very least, planting seeds indoors is a good cure for the winter doldrums—those bleak, cold days when February seems like a permanent condition and you feel you simply must do something to nudge the season into turning. Choose your earliest plantings judiciously, though. You don’t want them to be past their prime when you set them out in the garden. Onions, chives, peppers, certain wildflowers and perennial plants, and houseplants like coleus and geraniums are good candidates for starting very early.

Some varieties of vegetables and flowers can only be grown from seed.

FIRST THE SEEDS

You have in your hands a collection of seed packets and perhaps a few jars of seeds you’ve saved yourself.

You’re anxious to plant, to get a start on the growing season that still seems far away. Take a minute now, if you will, to be aware of what the seed really is before committing it to the soil. Dry, flaky, hard, smooth, warted, ridged, powdery, or wispy, these distinctively shaped particles may look as lifeless as the February garden patch. Don’t be deceived, though. Seeds don’t spring to life when you plant them. Seeds are alive.

Often symbols of beginnings, seeds are living guarantees of continuity between generations of plants. Inside even the most minute, dustlike grain of seed is a living plant. True, it’s in embryonic form, possessing only the most rudimentary parts, but it lives, and it is not completely passive. At levels that we can’t see but laboratory scientists can measure, seeds carry on respiration. They absorb oxygen and give off carbon dioxide. They also absorb water from the air. Seeds need a certain minimum amount of moisture within their cells to make possible the metabolic processes by which they convert some of their stored carbohydrates into available food. Thus they maintain their spark of life—dim though it may be—until conditions are right for them to complete their destiny as germinated plants.

Begin by gathering your stored and bought seeds.

THE BOTANICAL FACTS

By strict botanical definition, a seed is a ripened fertilized ovule containing an embryonic plant and a supply of stored food, all surrounded by a seed coat. A kernel of corn is really a seedlike fruit, called a caryopsis. Carrot, dill, and fennel seeds are also, technically, dry, one-seeded fruits. In practice, though, gardeners call many different botanical structures that are technically fruits (the mature ovary of a flower containing one or more seeds) seeds, a convention we will use in this book.

Seeds are completely self-contained. Within the boundaries of the hard, dry coat that protects them, they possess enough food energy to carry them through their dormancy and into their early days as seedlings. They have all the enzymes they’ll need to convert this stored food into a form their tissues can use, and they carry within their cells the genetic information that directs what they will be, and when, and how.

Let’s look at the bean as an example—not a typical seed, perhaps, but one in which it is easy to see the parts and their arrangement that are common to all seeds. The good old garden bean is the favorite of botanists for this purpose because its size and structure make it possible for us to see clearly how it is formed.

If you soak a bean seed in water for a few hours, the hard outer coat will slip off easily. The bulk of the bean that you now see is composed of the cotyledons, the two identical fleshy halves that comprise the “meat” of the seed. Cotyledons are rudimentary leaves. Unusually large and thick in the bean, they contain stored fat, carbohydrates, and protein. The cotyledons are attached to a rudimentary stem, and they curve protectively over a tiny leafy bud. The root tip, at the other end of the seed, will elongate into the first root of the plant when the seed germinates. Any seed, no matter how tiny, wispy, or irregular, will possess these features: cotyledons (sometimes one, more often two), a short stem, a leafy bud, and a root tip.

Most seed-bearing garden vegetable plants are dicots; that is, they possess two (di-) cotyledons (-cots). Beans, tomatoes, celery, cabbage, and other vegetable seedlings are dicots. When they germinate, they send up a shoot with two cotyledons. Corn, wheat, rye, and grasses are monocots, with just a single (mono-) cotyledon (-cots). These seeds send up the familiar, single grasslike spear (cotyledon) of green.

In many seeds, some of which are important food crops in their own right, the stored food is not contained in the cotyledons, as in the bean, but in a layer called the endosperm, which surrounds the embryo. This part of the seed varies in different species. It may consist of starch, oil, protein, or waxy or horny matter, but whatever its form, its function remains the same—to nourish the seed from the time of its maturity on the parent plant until the beginning of the next growing season, when conditions will be favorable for its success as a plant in its own right. Sometimes the tasty endosperm is what we’re after when we raise the crop, as with buckwheat, corn, wheat, and rye.

Cross sections of a bean seed, or dicot (top), and a corn seed, or monocot (bottom).

Germination of a bean seed (dicot).

Germination of a corn seed (monocot).

DORMANCY

If you’ve ever tried unsuccessfully to start a row of lettuce in midsummer heat, you have an idea of how a dormant seed behaves. It refuses to germinate, even if otherwise viable, when it lacks the right temperature, moisture, and oxygen supply that would ordinarily favor germination. Even though conditions might seem favorable for germination, such as those that occur in midsummer, they might not be right to induce germination in certain seeds.

It can be annoying to miss a seeding date for a certain crop and be unable to plant it later in the summer; however, the ability of seeds to remain dormant, in varying degrees, has contributed to the survival of seed-bearing plants as we know them. In this example, lettuce would have less of a chance of success when sown in hot, dry soil and hot, dry weather than it does in the cool, moist surroundings that promote its quick growth. Dormancy, then, is a protective device, designed to assure the continuity of the species.

A seed may be dormant because its embryo is still immature, its seed coat is impermeable to water or to gases, its coat is too unyielding to permit embryo growth (although this is rare), or because of a metabolic block within the embryo. Often, more than one of these factors operates at the same time.

BREAKING DORMANCY

As a gardener, it is often in your interest to try to break dormancy in certain kinds of seed. Since you intend to give the plant special care and optimum conditions, you can often do this and get away with it. For example, if you are anxious to raise a fine bed of lettuce to eat with your midsummer tomatoes—a real mark of gardening expertise—how do you give your lettuce seeds the message that it’s all right for them to sprout?

Here are some common ways to break seeds out of dormancy.

Temperature. A period of cold often helps break dormancy.

Light. Subjecting the seeds to light—even a dim continuous light or a sudden bright photoflash—will sometimes help (this is the case with lettuce). Germination depends on the total amount of light received. The dimmer the light, the longer the necessary exposure.

Dormancy is seldom a problem with vegetable seeds, except for some heat-sensitive seeds such as lettuce and celery. Beans, mustard, and many other vegetable seeds never go dormant. Carrots and parsnips do need a month of afterripening following harvest before they’ll germinate. Seeds you’ve purchased have had time, of course, to undergo any necessary afterripening in the months between collection and planting.

Dormancy issues are more common when trying to germinate the seeds of wildflowers, trees, or shrubs.

HISTORY OF SEED-BEARING PLANTS

Surprisingly, we know very little about the origin of seed-bearing plants. Charles Darwin called it an “abominable mystery.” Spore-bearing plants, like ferns, existed first, followed by the gymnosperms (the conifers we call evergreens), which shed their seeds naked (no seed coats). Discoveries of early seeds encased in cupules—incompletely fused seed coats—have pushed the date of known true seeds back to 360 million years ago. Angiosperms, flowering plants in which the seeds (encased in an ovary) are more fully protected, appeared during the Cretaceous period (roughly 100 million years ago). Eventually they dominated the more primitive spore-bearing forms of green life, presumably partly because the well-developed seed embryo, clinging to the parent plant until thoroughly mature, had the edge over the naked, randomly shed seed.

Although we still know so little, we know enough of the internal workings of the seed to stand in awe at its variety, its toughness, and its practical simplicity.

CHOOSE YOUR MEDIUM

The first step in encouraging your seeds to become the plants they really want to be is to choose a seed-starting mix that will nurture the seeds through the critical germination and seedling stages.

The stuff to which you entrust your seeds should match the following description:

Free from competing weed seeds, soilborne diseases, and fungus spores

Able to absorb and hold quantities of moisture

Able to drain quickly, leaving necessary air between moist particles

Fine textured

Organic and sustainable

Noncrusting

Since the physical conditions of their surroundings—temperature, moisture, air, and light—are more important to germinating seedlings than the nutrient content of the soil, these first mixtures in which you plant your seeds needn’t be rich. In fact, it’s better if they’re not. But they should be light, spongy, and moist. It’s easiest to start seeds in a commercial, organic seed-starting mix. Many good commercial mixtures are available, or you can mix your own using one of the recipes listed later in this chapter.

I wouldn’t recommend starting seeds in plain garden soil, because it tends to pack and crust when kept in shallow containers indoors. In addition, unsterilized garden soil may harbor fungi that cause damping-off, a disease that makes young seedlings shrivel and wilt at soil level and sometimes even interferes with complete germination. I find it easiest to use fresh seed-starting mix for each new seedling crop and to recycle the used mix for potting up young trees or rooted herbs. Mix in which diseased seedlings have been grown must be pasteurized (see “Heat Treatment” later in this chapter) before another batch of seeds is planted in it.

SEED-STARTING MIX OPTIONS

If you don’t want to use a premixed commercial seed-starting mix, any of the following will work. Your choice may depend partly on what is easily available to you and on your personal reactions to the feel of the stuff.

Whichever option you choose, be sure it is good and moist before you fill your containers and plant your seeds, as many of these mixes are difficult to get wet once they dry out (this goes for commercial mixes, too). Mix any components together thoroughly before adding water; a large old tub or bucket set on newspaper makes mixing and wetting easier and spillage less of a problem. When moistening seed-starting mixtures, I like to use warm water because it is more readily absorbed. For very dry materials, adding a couple of drops of natural dish soap can speed the wetting process. This seems to be especially important for mixtures containing sphagnum moss, which tends to float on cold water in a dustlike layer that takes ages to soften and swell. It is also a good idea to prepare your soil mixture several hours before you intend to plant seeds. Then, if you have added too much water, you can simply pour off any extra before planting the seeds.

Vermiculite, straight. This is a form of mica that has been “popped” like popcorn by exposing it to intense heat. The resulting flakes are light and capable of holding large amounts of water. Vermiculite also absorbs nutrients from fertilizers and other soil components and releases them gradually to plants. Be sure to buy horticultural vermiculite, not the kind sold for the building trade, which is coarser, highly alkaline, and often contains substances toxic to plant roots.

One part milled sphagnum moss and two parts each of vermiculite and perlite. This is very similar to many commercial mixes. (Equal parts of vermiculite, milled sphagnum moss, and perlite combine to make another good starting medium. This provides a spongy, friable seedbed that promotes good root development. Perlite, despite its plastic appearance, is a natural product, a form of “popped” volcanic ash, and while I do not like to use it alone, as I do vermiculite in some cases, it promotes good drainage in seed-starting mixes.)

A three-layer arrangement. Rather than a mix, this is composed of a bottom layer—about ½ inch—of torn pieces of sphagnum moss that has been well dampened, then a 1-inch layer of good soil or potting mix, topped by a ½-inch layer of vermiculite. The bottom layer of moss should not be finely milled. The air spaces trapped by the ferny fronds of the undecomposed moss promote excellent root development, I’ve found, and the moss retains water, too. I tear up the wads of moss into small pieces so that the roots of individual plants can be removed more easily when it’s time to transplant them. You can also mix chopped undecomposed sphagnum moss with other potting-soil ingredients. Some evidence has shown that sphagnum moss exerts a mild antibiotic effect that helps to control bacterial diseases of seedlings. (A disease-causing fungus, Sporotrichum schenckii, is occasionally present in sphagnum moss. Wash thoroughly after handling the moss, and wear gloves if you have any skin breaks on your hands.)

A cube of sod. Turned grass side down, sod works well for the planting of larger seeds, such as squash, melons, and cucumbers, and supports the seedling until it is planted out in the garden.

FEEDING YOUR SEEDLINGS

Neither vermiculite, perlite, nor sphagnum moss contains the nutrients necessary to support plant growth. Seedlings growing in these substances, or mixtures of them, must be fed regularly after the first few weeks until they get their roots into real soil or an enriched potting mix. The easiest way to do this is to buy a commercial concentrated organic liquid plant fertilizer and add it to the water as directed on the package.

Such liquid feeding, carried on over a period of weeks, amounts to hydroponic culture, with the growing medium serving only to hold the plants upright and to condition the roots. Growing seedlings benefit from the more complex interactions taking place in real soil, so they should be transplanted into the garden as soon as practical or into a potting mix when they need more space.

POTTING MIXTURES

A seed-starting mix provides good physical conditions for seed germination; but a potting mix also contains nourishment to support the growing plant. Potting mixes tend to be courser in texture than seed-starting mixes. Good commercial organic potting mixes (potting soil) are readily available. Read the labels to find one that matches your plants and preferences.

If you prefer to blend your own, there are many recipes from which to choose. Here are some options, along with a few hints about their suitability or limitations.

The amounts in each recipe are given in parts. A part, of course, can be any measure of volume ranging from a teacup to a bushel basket, as long as the measurement used is consistent. I’d suggest making up more soil mix than you think you’ll need while you have all the ingredients assembled. Mix the components thoroughly as you go, just as if you were making granola.

Cruso’s Potting Soil

1 part commercial potting soil or leaf mold

1 part sphagnum moss or peat moss

1 part perlite or sharp sand

This is the formula for potting soil that Thalassa Cruso recommends in her book Making Things Grow. For fast-growing seedlings, I like to change the proportions to two parts soil or one part soil and one part compost, mixed with one part moss and one part sand or perlite. As originally formulated, for houseplants, the mixture is a bit lean to support strong seedling growth.

Good and Simple Potting Soil

1 part finished compost

1 part vermiculite

This is easy to mix. Moisten it well before setting plants in it.

Home-Style Potting Soil

1 part finished compost

1 part either loose garden soil or potting soil

1 part sharp sand, perlite, or vermiculite, or a mixture of all three

This mix can be made without buying any ingredients if you have access to sharp sand.

A Rich Potting Soil

1 part leaf mold (slowly composted leaves)

2 parts loose garden soil

1 part compost or rotted, sifted manure

This potting soil is especially good for lettuce and cabbage transplants.

A Lean Potting Soil

1 part loose garden soil

1 part perlite

1 part vermiculite

1 part milled sphagnum moss

1 part sharp sand

This is mostly physical support for the plants. Use this mixture for plants that should grow slowly, such as cactus.

Amended Potting Soil

4 parts loose garden soil

2 parts sphagnum moss or peat moss

2 parts leaf mold or compost

2 parts vermiculite

6 teaspoons dolomitic limestone

The limestone in this potting soil helps to neutralize acids in the leaf mold and peat moss.

If you want to formulate your own potting mixture from what you have or can readily find, you’ll probably be on safe ground if you include each of the following:

Good garden soil, preferably loam, for nutrients

Sand or perlite for drainage (Gravel may also be used in the bottom of a solid container but not as part of a soil mix.)

Compost, leaf mold, vermiculite, or moss for water retention

HEAT TREATMENT

Commercial potting soil should be free of harmful bacteria and fungi, but garden soil is, of course, teeming with organisms. Most of them are beneficial. I never heat-treat or otherwise “sterilize” my soil. Besides being a large nuisance, the process kills helpful soil organisms and, at temperatures above 180°F (82°C), releases dissolved salts that can be toxic to plants. Even at 160°F (71°C), some salt-releasing breakdown occurs. If you decide to sterilize a batch of soil, the following methods will work. Plan a picnic supper or weekend trip when you do treat your soil indoors, because the kitchen will smell awful!

Using the oven. Before heating the soil, moisten it thoroughly so that small puddles form when you press your finger into it. Bake the soil in metal pans in a preheated 275°F (135°C) oven. Small amounts, a gallon or so by volume, should be ready within 30 to 40 minutes. Larger quantities, a half bushel or so, may need to remain in the oven for 1½ hours. It is important that the soil be wet. The steam generated by the water penetrates the spaces in the soil. Dry soil takes much longer to treat and smells much worse.

A meat thermometer inserted in the soil will indicate when it has arrived at the proper temperature to kill offending organisms. Damping-off fungi, for example, die at 130°F (54°C), and a temperature of 160°F (71°C) kills most other plant viruses and pathogenic bacteria. Avoid overheating the soil, for you want to retain as many of the more numerous helpful soil microorganisms as possible. Soil that has been baked should be rubbed through a hardware cloth screen to break up the clumps before using.

Using the microwave. Soil poured into plastic bags can be sterilized in a microwave oven. Do this in batches of up to 10 pounds. Placing the bags in the oven for 7½ minutes will kill most damping-off and root-rot fungi. Some researchers report, however, that microwave treatment changes soil characteristics such as pH, mineral content, and cation exchange capacity (the soil’s ability to react with positively charged molecules).

Using boiling water. Pouring boiling water over a flat of soil does not sterilize it but kills many microorganisms.

Using solar energy. Solarizing is a great way to kill off soilborne problems and even some weed seeds. Place the mix or soil in a clear plastic bag. Tie the bag closed and put it in a location where it will receive full sun. Two weeks of direct-sun treatment in warm weather should kill most disease organisms.

TABLE 1

TEMPERATURE NECESSARY TO KILL SOIL-INHABITING PESTS AND DISEASES

PESTS (30 MINUTES AT TEMPERATURE)
Nematodes 120°F
Damping-off and soft-rot organisms 130°F
Most pathogenic bacteria and fungi 150°F
Soil insects and most plant viruses 160°F
Most weed seeds 175°F
A few resistant weeds, resistant viruses 212°F

Source: George “Doc” Abraham and Katy Abraham, Organic Gardening under Glass (Emmaus, PA: Rodale, 1975).

A NOTE ABOUT PEAT MOSS AND PEAT MOSS ALTERNATIVES

For the past century or so, gardeners have used “peat moss” (the crumbly, dark brown material that results when sphagnum peat moss slowly decomposes) as a soil amendment for lightening clay soil and as an ingredient in seed-starting mixes and potting mixes. Peat is generally sterile, free of weed seeds, and a natural suppressant of damping-off, a fungal disease that can kill seedlings, making peat an effective, natural choice for seed starting.

But natural and renewable as peat may be, our love affair with peat moss means we have been harvesting it far faster than nature can make it. Peat is mined by stripping off the top, living layer of a bog (most of what we get in the United States comes from Canada) and scooping up the deep layer of decomposed material underneath with huge earthmoving equipment. A peat bog only makes about 116 inch of peat a year, so it takes a long, long time to accumulate the layer humans can harvest in a few hours.

But worse than that is the fact that peat bogs sequester an estimated one-third of all the carbon tied up in plant-derived material on the planet. This is because cool temperatures where sphagnum moss grows and the waterlogged conditions of a peat bog mean decomposition is so slow that the carbon caught in peat can be tied up for centuries or millennia if left undisturbed.

Once the peat is harvested, moved to warmer climates, and used in container mixes and gardens, it begins to decompose, releasing all that sequestered carbon back into the air, something scientists increasingly suggest that we should avoid.

Luckily there are more ecologically sensitive alternatives that serve the same function as peat moss in seed-starting and potting mixes. Many are made from agricultural by-products, so they serve to recycle materials that were previously discarded—an added benefit.

Peat Alternatives

Compost. Sieved compost is a great ingredient for mixes and inexpensive to make at home. Home piles rarely get hot enough to kill weed seeds, so you may want to set up a separate bin and make a batch of compost from weed-free materials each year to use for blending your own seed-starting mix.

Worm castings (vermicompost). A great compost for using in mixes that you can make at home, this is rich in nutrients plus a healthy serving of microorganisms. If you feed your worms carefully, it is also free of weed seeds.

Composted bark. A high-quality material used as a major component of some commercial potting mixes, it breaks down more slowly than compost made from weeds and kitchen waste.

Coir (coconut fiber). This high-quality material made from coconut husks has an exceptional capacity to hold air and water. It is bulkier than peat moss and breaks down more slowly.

Rice hulls. Another agricultural waste product being recycled for growing plants, rice hulls are not a peat alternative, but they can stand in for perlite and vermiculite in mixes (eliminating the fossil fuel required to expand natural rock into those porous products) to add air spaces and water-holding capacity.

CHOOSE YOUR CONTAINERS

Your seeds are ready. Your seed-starting mix is ready. Now it’s time to break out your saved flats and pots and comb closets, attic, and cellar for likely discards that will provide a temporary home for your growing seedlings.

The ideal container for starting seeds is 2 to 3 inches deep (deeper will only use up more seed-starting mix). Anything shallower will dry out quickly and limit root development. The soil holders you use for germinating seeds do not necessarily need to have drainage holes. You can prevent pooling of water around plant roots by choosing the right seed-starting mix to fill the containers (see Chapter 3). But containers with holes, set on a tray or in a larger container to catch excess water, are more forgiving of overwatering.

Note: Long, narrow flats fit neatly under fluorescent lights; however, don’t use flats that are so long or large that they will be heavy and difficult to handle when filled with wet seed-starting mix. Smaller containers are also easier, as you can plant just one type of seed in each and then move just those seedlings when they are ready to transplant.

TYPES OF CONTAINERS

I’ve grown seedlings in all of the following kinds of containers, for different reasons and with varying results. Some are more useful than others. Certainly, it is admirable, all else being equal, to make use of some of the many throwaways that clutter our daily lives, but there are times when a specially prepared device will be more effective than anything else. At any rate, here’s my list of container candidates, briefly evaluated for effectiveness, cost, and useful life.

Found/Repurposed

Cottage cheese, yogurt, and other plastic food containers. These cost nothing and outlast at least one use. I use them primarily for giveaway seedlings, because in my setup the round shape of the containers wastes space under the lights. They do fit on most windowsills, though, which can be a boon to the gardener without lights. I’m especially fond of the 2-inch-deep, rectangular trays my supermarket sells mushrooms in. They are the perfect size for starting four to six seedlings, and the shape is efficient on windowsills or under lights.

Beverage cartons. Yes, they’re free and good for one growing season, and they fit together well under lights. You can either halve a half-gallon carton the long way or cut one side out of a quart carton. If you don’t buy beverages in cartons, no doubt your friends, relatives, or neighbors would save their cartons for you. Even the little pint and half-pint cartons may be used for individual transplants.

Aluminum disposable pans. Aluminum loaf pans make fine seedling trays. They last for several years, work quite well, and can be had free if you know people who will save them for you. The shiny sides of the loaf pan reflect light back onto the seedlings. One of my best generations of eggplant seedlings was raised in an aluminum loaf pan on the kitchen windowsill. Pie pans are more of a last resort for plants, for they are too shallow to hold enough soil for proper moisture retention and root development. They’re fine for sprouting seeds, though, if you transplant promptly.

Plastic gallon jugs. Cut-down plastic gallon jugs have worked fairly well for me, but I prefer the long, narrow cut-down milk cartons, which seem to accommodate more seedlings and waste less space under lights. Plastic jugs are free, lightweight, last 2 to 3 years, and may be further recycled by saving the cutoff top to put over seedling plants in the garden for frost protection.

Any of a variety of containers, bought or found, can be used to start seedlings

Purchased

Multicell plastic flat inserts. Just about every seedling for sale in stores come in these thin plastic containers. Often sold in flat sheets, they are perforated for dividing into smaller units. You can buy them new, reuse any you buy, and often find boxes of emptied ones for free from friends or Craigslisters. With a little care, they last for a few seasons.

A commercial self-watering system

Peat pots. A tray of seedlings all tucked into peat pots looks neat and satisfying, but despite the assumption that plant roots will readily penetrate the walls of the pot and find the surrounding soil, I have not found this to be true in all cases. More than once I’ve uprooted a plant and found its roots pretty well confined to the peat pot. Also, unless grouped closely together, peat pots dry out fast. There are better choices.

Compressed peat pellets. These compressed-soil blocks in netting or unwoven fabric seem to offer less resistance to plant roots than the peat pots, if you remove the net when you plant the seedlings out. However, even though the net has air spaces, it often appears to inhibit plant roots. Avoid those that contain synthetic chemical fertilizer. Peat pellets are easy to use and neat, but they are expensive and can’t be reused.

Fiber market packs. These are small rectangular trays made of pressed fiber. I think they are preferable to peat pots. The packs are not cheap, but they last for several years, fit together well in storage, and allow plenty of depth for root development. Also, unlike the larger flats, they may be kept on a sunny windowsill.

Flower pots. Clay pots last a long time and are fine for special transplants. They are the best containers for starting watercress seeds, because they can be kept in a tray of water so that the soil is constantly moist. As far as I’m concerned, though, they are too costly and unwieldy for most transplanting. I use small plastic pots to start cucumber and melon seedlings.

Speedling flats. A more serious competitor for my favorite plain old rectangular flat is the Speedling flat—a molded plastic-foam tray 3 inches high, 13 inches wide, and 26 inches long. The plant-holding cells taper to a narrow open point at the bottom of each cell—an ingenious way to encourage a dense root-ball that makes good use of the soil mix. In order to keep the roots confined to their spaces, the foam trays must be propped an inch or so above the surface to admit air. In my trials, foam flats produce excellent seedlings, but they’re a bit more cumbersome to work with than conventional flats. They’re durable, though; mine is still in use after 4 years.

Soil blocks. Technically not containers, just naked seed-starting mix, soil blocks promote good root growth without forming a barrier. They take time and special equipment to make, though. You need a soil-block mold (a metal device with a plunger that ejects blocks of soil from a mold), a tub for mixing, a suitable seed-starting mix, water, and a tray.

To make a soil block, wet the mix until it forms a slurry. Then pack a four-cube block maker with the wet mix, level off the top of the mold, and eject the cubes onto a tray. Plant a single seed in each block, or plant two and cut off the extra seedling if both germinate.

In my experiments with soil blocks, I found that they do indeed promote good root growth. They aren’t for everyone, and they must be very carefully and frequently watered from above so they don’t disintegrate.

Newspaper pots. You can make really good seedling containers out of newspaper. They are free and easy on seedlings’ delicate roots because you plant the paper along with the plant. To make them, get a juice glass or small jar/bottle that’s 2 to 3 inches across and at least 4 inches tall. Tear long strips of newspaper about 6 inches wide. Wrap each strip around the glass, allowing 2 inches of the newspaper to stick out beyond the bottom of the glass. Fold and flatten that extra paper against the bottom of your glass, slip the paper pot off the glass, and immediately fill it nearly to the top with seed-starting medium to help it hold its shape.

Plastic flats.