GARDENING UNDER LIGHTS GARDENING TIMBER PRESS • PORTLAND, OREGON UNDER LIGHTS The Complete Guide for Indoor Growers L E S L I E F. H A L L E C K • • • 4 CONTENTS Copyright © 2018 by Leslie F. Halleck. All rights reserved. Photo and illustration credits appear on page 235. Published in 2018 by Timber Press, Inc. The Haseltine Building 133 S.W. Second Avenue, Suite 450 Portland, Oregon 97204-3527 timberpress.com Printed in China Text and cover design by Adrianna Sutton Library of Congress Cataloging-in-Publication Data Names: Halleck, Leslie F., author. Title: Gardening under lights: the complete guide for indoor growers / Leslie F. Halleck. Description: Portland, Oregon: Timber Press, 2018. | Includes bibliographical references and index. | Identifers: LCCN 2018001914 (print) | LCCN 2018004015 (ebook) | ISBN 9781604698657 | ISBN 9781604697957 (hardcover) Subjects: LCSH: Artifcial light gardening. | Indoor gardens. Classifcation: LCC SB126 (ebook) | LCC SB126 .H35 2018 (print) | DDC 631.5/83—dc23 LC record available at https://lccn.loc.gov/2018001914 A catalog record for this book is also available from the British Library. C O N T E N T S Preface • 6 Introduction • 9 LIGHT PLANTS Why Plants Need Light • 12 Edible Plants • 152 How Plants Respond to Light • 18 Ornamental Plants • 198 Measuring Light • 36 Grow Lamps • 52 Conclusion • 228 Resources • 230 References and Bibliography • 233 GROWING Photography and Illustration Credits • 235 Acknowledgments • 236 CONDITIONS Index • 237 Managing Your Environment • 88 Common Pests and Diseases • 108 Propagation and Plant Care • 120 PREFACE • • • 6 Being obsessed with plants by the time I was 18 years old didn’t exactly make me popular at parties. As my original plant friend, Carolyn, will tell you, the two of us could clear a room quickly once the surrounding college partygoers heard us talking about our cactus or cross-pollination. We just couldn’t help ourselves, and we’re still at it today. However, my status at The University of North Texas as one of only two students (at the time) concen- trating in botany, my curious reputation as a gardener, and my college job as a garden-center employee made my phone ring a bit more frequently than my social status warranted. If only I had known I could have made some cash telling anonymous callers how to stop killing their closet so-called tomato plants. But I was never interested in what was actually growing in their closets. I was content to be knee-deep in my outdoor ornamental and vegetable garden, not to mention obsessed with an increasingly large collection of houseplants. But I’m glad those closet garden- ers called, because it was the start of my horticultural consulting career—and, as it turns out, this book. I spent my frst two years of university life at UNT as an art major before I switched to biology and botany. As such, aesthetic considerations are infused into all my pursuits, even the scien- tifc ones. The fusion of art and horticulture is natural. Growing plants and food indoors doesn’t have to be utilitarian; it can be a beautiful practice that blends into our living space and lifestyles. Within this book you’ll fnd examples and inspiration for your 7 • own attractive plant lighting. As a graduate student at Michigan State University, my research focused on greenhouse production and fowering of perennial plants. Therefore, you will also encounter some science and math, which may seem a bit confounding at frst. If you don’t need this information, feel free to skip it. If you have intensive indoor gardening goals, however, the more in-depth how-tos on measuring and calculating your indoor lighting needs will likely form the basis of your long-term success. As it turns out, writing this book feels like I’m coming full circle to bring the closet garden to light. I hope this book encourages your interest in, and creates new possibilities for, growing plants where you once thought you could not. Perhaps you’re on a mis- sion to grow more of your own food or medicinals, even if all you have is a kitchen counter, a guest room corner, or a small closet. You may want to extend your vegetable-gardening season by get- ting a jump-start on propagation or growing indoors off-season. Having control over your own food source is a powerful feeling. It’s good to eat fresh, hyperlocal, and clean. Or maybe, like me all those years ago, you have caught the plant-collecting bug and there just aren’t enough windowsills left in your home to feed your growing plant family. In any case, you’ve come to the right place. • • Some plants, such as haworthias, can survive in a windowsill. INTRODUCTION 9 • My window is bright enough, right? New indoor growers ask this hopeful question all too frequently. While many books and websites insist that you need only a bright window to get your tomato seeds going or your orchids reblooming, this approach can result in a lot of disappointment. Ambient light levels inside your home are signifcantly lower in intensity and ultimately different in spectrum than natural outdoor light, especially during the winter months. Even a seemingly bright window may not provide enough light, or the right kind, for young seedlings or fruit-producing plants. Have you ever started seeds indoors in a sunny window, only to watch the tiny seedlings lean so far that they topple over? Perhaps you’ve tried some beautiful succulents and watched them do the same. Your plants are starving for, and stretching toward, the light. There are plenty of low-light tropicals and blooming plants that you can grow successfully indoors with good ambient light, and you can maintain cer- tain light-loving succulents for a while in a windowsill. But even a bright win- dowsill is typically not the right location for plants you intend to harvest for food. The same goes for heavy-blooming plants. Reproduction is an energy-intensive process. Producing fowers, fruit, and seed requires a lot of juice. Plants need enough light, and the right kind of light, to get the job done. You may have learned that in your outdoor garden, plants that produce large fruit, such as tomatoes, require roughly double the duration and intensity of direct sunlight as plants that produce mostly foliage, such as leafy greens and lettuce. A plant’s heritage—that is, the geographical area where it naturally evolved— dictates its requirements for specifc light intensity, duration, and spectrum to reproduce successfully. If you are going to invest time, effort, and money in indoor growing, quality supplemental lighting should be your number-one priority. Before we draw up your shopping list of types of lamps and gear you should be using indoors, or determining how many lamps you will need for different types of plants, we must understand how plants use light; how to distinguish light quality, quantity, and duration; and how to measure each. Artifcial lighting is complex, • •