Seed-Starting 101: Starting Seeds Under Protection

This is part 2 of a six-part series on seed starting. Part 1 can be read here.

Starting seeds early, when done right, is one of the most satisfying aspects of gardening. To see young, green shoots perk up through the soil while winter carries on outside is incredibly gratifying. It’s as if spring begins as soon as the first cotyledons (first leaves) pop open. It’s also an essential part of growing tomatoes, peppers, eggplant, and other crops, which otherwise don’t have a long enough season in northern climates to mature much ripe fruit.

For the home gardener lacking a heated greenhouse, there are two main ways to start seeds under protection: indoors or in a cold frame. We’ll take a look at both strategies.


Our friend Kerry Trueman demonstrates her own indoor seed-starting technique–with decopage!–in this great video:

(Check out for more New York-based food and gardening content.)

For many gardeners, starting seeds indoors is the preferred, tried-and-true method. However, despite what most people believe, to be successful requires more than just a sunny windowsill. Successful indoor seed-starting requires the following components.

Summary: Starting seeds indoors is convenient and accessible to all gardeners. Little time or money needed for infrastructure. Supplemental lighting is almost always necessary: don’t skip it! Seedlings grown indoors are ultra-tender and require careful hardening off.


(Above, a photo of a homemade cold frame produced from easily obtained materials. Instructions on how to build this cold frame will be covered in this series.)

A cold frame is a simple structure placed in the garden that features structural sides (usually made of wood) and a top made of a transparent material such as clear plastic or glass. Starting seeds in a cold frame eliminates several of the difficulties of starting seeds indoors. However, it requires a small investment of time and money in the construction of the cold frame and careful attention on cold nights. Here’s a brief run down of what you need to know for successful cold-frame seed-starting.

Summary: Cold frames provide an ideal environment for seed-starting. Gardeners are assured ample natural light and need not bother with much hardening off before transplanting. Cold nights are an issue: gardeners must monitor for sub-26 temps and provide additional insulation or supplemental heat on those nights if frost-tender crops are in the cold frame.

Originally published on the Hudson Valley Seed Library blog

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  1. Ann
    Thursday, March 8th, 2018
    This was really helpful information for me and my 5 year old son who wants to starts some seedlings to sell this spring. We have a cold frame but I learned a lot about how to properly use it from this article. Thanks!