Decoding gardening advice : the science behind the 100 most common recommendations

225 Pages·2012·2.32 MB·English

by  Gillman

Decoding
Gardening
Advice
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Decoding
Gardening
Advice
THE SCIENCE BEHIND THE
100 MOST COMMON
RECOMMENDATIONS
Jeff Gillman & Meleah Maynard
Timber Press
PORTLAND • LONDON
Copyright © 2012 by Jeff Gillman and Meleah Maynard.
All rights reserved.
Published in 2012 by Timber Press, Inc.
The Haseltine Building
133 S.W. Second Avenue, Suite 450
Portland, Oregon 97204-3527
timberpress.com
2 The Quadrant
135 Salusbury Road
London NW6 6RJ
timberpress.co.uk
Printed in the United States of America
Library of Congress Cataloging-in-Publication Data
Gillman, Jeff, 1969-
Decoding garden advice : the science behind the 100 most common recommendations /
Jeff Gillman and Meleah Maynard. – 1st ed.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-60469-220-4
1. Gardening. I. Maynard, Meleah. II. Title. III. Title: Good and bad gardening advice
and how to tell the difference.
SB450.97.G55 2011
635–dc22
2011013138
A catalog record for this book is also available from the British Library.
For Suzanne,
Catherine, and Clare
For Mike,
who did everything that needed doing
while I wrote
CONTENTS
Acknowledgments 8
Introduction 9
1
SOIL ..................................................................................12
Organic material Earthworms Vermicompost Soil tests Lime Sulfur Fertilizing
and the weather Soil in containers Urine as fertilizer Fertilizing in spring Peat
moss Yearly fertilizing Tilling Organic versus synthetic fertilizers Ammonium
and nitrate Bacteria and beans Mycorrhizae Balanced fertilizers Pine needles
Compost tea Sand
2
WATER .............................................................................54
Watering depth and frequency Planting trees and shrubs Time of day Checking
soil moisture Overhead watering Watering trees Withholding water Drainage in
containers
3
PEST, DISEASE, AND WEED CONTROL .....................68
Insecticidal soaps Timing of pesticide application Homemade deer repellents
Organic versus synthetic pest control Homemade insect sprays Corn gluten
meal Ladybeetles Glyphosate Controlling small mammals Pesticide shelf life
4
MULCH ...........................................................................86
Organic versus inorganic mulches Mulch placement The necessity of mulching
Winter mulch Landscape fabric Wood mulch Nitrogen and wood mulch
5
ANNUALS, PERENNIALS, AND BULBS ......................102
Deadheading Hardiness zones Hardening off seedlings Root-bound plants Planting
non-natives Perennial beds beneath trees Disease-resistant cultivars When to plant
perennials Spacing recommendations Grow lights Light levels Sterilizing containers
Dividing and transplanting Phosphorus
6
TREES AND SHRUBS ...................................................134
Dividing shrubs Pruning Planting depth Planting hole size Soil level Fertilizing
Staking Tree wraps Wrapping evergreens Balled-and-burlapped trees Topping
trees Dressing pruning wounds Pruning at planting Beating trees Pruning cuts
Shearing deciduous shrubs
7
VEGETABLES AND FRUIT ............................................162
Pruning fruit trees Eggshells and tomatoes Crop rotation Thinning seedlings
Weeding Hybrid versus nonhybrid seeds Treated lumber Planting in rows Lunar
gardening Companion planting Vegetables in containers Light levels
8
LAWN CARE ...................................................................188
Dog spots Yard waste disposal Mower height Cutting grass Seeding Low-input
grasses Sod versus seed Borax Light levels Lawn chemical safety Fertilizers and
pollution Organic fertilizers Grass clippings Brown lawns Synthetic fertilizers and
insecticides Overwatering
Conclusion 216
Helpful Conversions 217
Selected Bibliography 218
Index 219
ACKNOWLEDGMENTS
Many thanks to all of the kind and generous master gardeners, farmers,
horticulturists, professors, garden writers, entomologists, and research-
ers who offered opinions, advice, and their own stories of gardening suc-
cesses and failures. Your humor and wisdom helped shape this book,
and we are deeply grateful. Special thanks to master gardener Theresa
Rooney, whose encyclopedic gardening knowledge and good cheer are un-
paralleled. Thanks, as always, to Chad Giblin for helping Jeff out while
he was off writing. We also deeply appreciate the thoughtful work of our
copyeditor, Lisa DiDonato Brousseau.
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INTRODUCTION
As an associate professor of horticulture at the University of Minnesota
(Jeff) and a master gardener (Meleah), we field questions all the time
about everything from watering and soil preparation to fertilizing, prun-
ing, and chemical use. We didn’t realize how many dos, don’ts, and shoulds
there are to gardening until people started asking us these questions,
half of which we couldn’t answer without poring over garden books and
research papers ourselves.
One afternoon we were talking about the sorts of things we’re asked most
often, and we were shocked to realize how much advice gardeners at all
levels are bombarded with. Who could possibly make sense of it all? What
bothered us most was knowing that the confusion caused by this moun-
tain of sometimes contradictory advice may turn gardening into a joyless,
by-the-numbers exercise. Some would-be gardeners get scared, thinking
they will never figure it all out. Others, believing that gardening is not
going to be all that fun or relaxing after all, turn to seemingly less compli-
cated pastimes, like jogging or tossing horseshoes.
And, so, fueled by a love of horticulture—and Meleah’s aversion to sports
(Jeff likes football)—we decided to write this book. In these pages we offer
our fact-based thoughts on the usefulness and worthiness of some of the
dos, don’ts, and shoulds we hear most often. It was no easy task to whittle
these bits of advice down. You may not find every piece of advice you’re
wondering about, but we do hope to clear up a good share of the confusion
that’s out there.
As we dissected these various pieces of advice—good or bad—one of our
objectives was to explain the reasoning and the research behind them.
How often do you just do something in the garden because you have heard
it’s what you should do? Water deeply and infrequently, for example, or
stop fertilizing in late summer. Why? It’s important that gardeners know
why we should do some things, but should not do others.
This book covers a wide range of subjects, such as soil, mulch, water, trees
and shrubs, and vegetables. Each chapter is divided into three sections by
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