Guide to Planting Seedlings in Spring

Susan Glaese shares her guide to planting seedlings in spring, including tips on planting temperature, water, transplanting, food, wind and light.

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    Hardening off seedlings is a gardener's way of doing the same thing for plants. You can't just take young sprouts that have grown vigorously in a warm indoor environment, plunk them outside into the cool spring ground, and expect them to thrive.
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    Diagrams for optimum germination temperature and range degrees Fahrenheit and optimum growing temperature and range degrees Fahrenheit.

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When I moved from Florida — where gardens do best in January! — to the MOTHER EARTH NEWS EcoVillage in western North Carolina [EDITOR'S NOTE: Susan is our head gardener], the first cold snap found me with frozen laundry on my clothesline and in need of a strange (to me) tool I'd heard referred to as an "ice scraper." I began to wonder if I'd survive this experience called winter! But it didn't take me long to discover the secret of getting through the season: Avoid extremes. I noticed that people who kept their homes "August warm" would chill to the bone — and often take sick — when they had to go outside . . . but others, whose homes were considerably cooler, had no trouble adjusting to the outdoor air. I chose to mimic the latter and was soon hardening myself off to the cold.

Guide to Planting Seedlings in Spring

Hardening off seedlings is a gardener's way of doing the same thing for plants. You can't just take young sprouts that have grown vigorously in a warm indoor environment, plunk them outside into the cool spring ground, and expect them to thrive. Instead, you must toughen them up for the transition by gradually adjusting their temperature, water, food, and exposure to wind and sunlight. In this way when planting seedlings out, you'll produce stocky, thick growth that's less vulnerable to cold, wind, and disease.

Begin this process one to two weeks before transplanting by setting your starts outdoors for a few hours in the afternoon. Choose a sunny location that's protected from strong winds. Cold frames are wonderful tools for this, but there are plenty of other suitable methods, such as placing the plants on a protected patio or by the sunny side of a building. After two or three days of this initiation, your plants will be ready to stay out from morning to late afternoon for the remainder of the week. Then, if the weather promises to be mild, let them "camp out" for a few nights in final preparation.


I like to further ease my seedlings' transition by surrounding them with cool temperatures right from the start. It may surprise you to know that, although most plants prefer a warm atmosphere for germination, their optimum growing temperatures are on the cool side (see the accompanying chart in the image gallery). For instance, while broccoli, Brussels sprouts, cabbage, cauliflower, Swiss chard, collards, Chinese cabbage, kale, lettuce, and parsley prefer germination temperatures from the mid-70s to the 80s, they actually grow best between 60 degrees and 65 degrees Fahrenheit.


To help a plant harden off, you should also restrict its water supply. So give your seedlings' soil a chance to dry out some during those transition days. You might even let leaves droop just a little before you water. (And try to water only on sunny days — doing so reduces overchilling.)


Alan Chadwick, founder of the biodynamic/French intensive method, used to speak of the "breakfast, lunch, and dinner" concept of nurturing young plants: Give them a good "breakfast" in their first seed tray, a nutritious "lunch" in their second flat, and when they're hungry and ready — a hearty "supper" in the fertile soil of their garden home. By the time you're ready to plant out, the breakfast and lunch you've provided for your plants indoors should be almost used up. Then the plants will respond all the more eagerly to the rich dinner you've prepared for them in the garden.

4/15/2013 10:18:46 AM

Can I plant seedlings in compost?



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