Most beginners plant once, in spring. A late-summer sowing of lettuce, radish, kale and cilantro often does better, because the weather is cooling down instead of heating up.
When to sow, counted back from your first fall frost
| Plant | Sow this long before your average first fall frost |
|---|---|
| Leaf lettuce | 8–12 weeks. Aim to finish harvesting 1–2 weeks before frost. |
| Kale | 6–10 weeks. Frost improves the flavor, and established kale tolerates 15–20°F. |
| Radish | About 6–10 weeks; last sowing about 6 weeks before frost. Pull before a hard freeze. |
| Cilantro | About 8–10 weeks. Light frost does not hurt mature plants; a hard freeze kills them. |
The radish and cilantro windows are our own arithmetic from their days to harvest, because the Extension sources we read do not give them in weeks before frost. Days get shorter in fall, so plants grow more slowly than the seed packet says; Maryland Extension adds 10–14 days to the days to maturity for that reason.
Two things that go wrong in late summer
- Heat at sowing time. Lettuce seed germinates poorly above 80°F. Keep the pot in a cool, shaded spot until the seedlings are up, and keep the surface moist.
- Sowing too late. A plant that is half grown when the cold arrives stops there. If you are past the window, sow radishes: they are the quickest.
What stays out
Mint and chives are perennials and come back in spring. Kale can be picked into winter in many places. Basil, beans, tomatoes and peppers end with the first frost: pick everything usable when one is forecast.
Sources
Every fact in this guide comes from the publications below. None of them reviewed or endorsed Balcony Bounty.
- Utah State University Extension. How to Grow Lettuce in Your Garden. extension.usu.edu/yardandgarden/research/lettuce-in-the-garden
- University of Maryland Extension. Growing Leafy Greens in a Home Garden. extension.umd.edu/resource/growing-leafy-greens-home-garden
- Utah State University Extension. How to Grow Kale in Your Garden. extension.usu.edu/yardandgarden/research/kale-in-the-garden
- Utah State University Extension. How to Grow Radishes in Your Garden. extension.usu.edu/yardandgarden/research/radishes-in-the-garden
- University of Illinois Extension. Home Vegetable Gardening: Radish. extension.illinois.edu/gardening/radish
- Oregon State University Extension. How to grow cilantro leaves or coriander seeds. extension.oregonstate.edu/news/how-grow-cilantro-leaves-or-coriander-s…
- University of Wisconsin–Madison Extension. Cilantro / Coriander, Coriandrum sativum. hort.extension.wisc.edu/articles/cilantro-coriander-coriandrum-sativum…
- NC State Extension Gardener Plant Toolbox. Mentha spicata (spearmint). plants.ces.ncsu.edu/plants/mentha-spicata/
- NC State Extension Gardener Plant Toolbox. Allium schoenoprasum (chives). plants.ces.ncsu.edu/plants/allium-schoenoprasum/
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