9 Cold-Hardy Crops to Sow in Late Summer for a Fall Harvest

By late summer the garden looks like it’s winding down — the lettuce has bolted, the spring greens are a memory, and the tomatoes are demanding all your attention. But this is the exact moment to start the second harvest of the year. Sow the right crops in the warm soil of August, and you’ll be pulling fresh, frost-sweetened food (University of Maryland Extension) out of the garden long after the first cold nights have flattened everything tender.

The short version: cold-hardy crops — the leafy greens and root vegetables that shrug off frost — are what carry a garden into fall and winter. Sow them now while the soil is warm enough for fast germination, and they’ll mature in the cool weather they actually prefer. Below are nine of the most reliable, the frost math that tells you which ones fit your season, and how to get seeds up when the soil is still summer-hot.

When sowing fall gardens in the tail end of a heat wave, the planting is easy — the trick is keeping the seed bed cool and moist until the seedlings are established. We’ll cover both.

First, the Frost Math That Makes It Work

Before you pick crops, find your average first fall frost date — your local extension office publishes it — and count backward. The formula is simple:

Days to maturity + ~14 days (fall factor) = how far ahead of frost you must sow. (University of Maryland Extension)

That fall factor accounts for the shorter, cooler days of autumn, which slow growth compared with spring. If a crop’s adjusted time fits inside your window, it’s fair game to sow now. This is why two gardeners in different regions plant very different things in the same week — it’s all about days to frost, not the calendar.

Here’s where the nine crops fall, using extension days-to-maturity ranges (Iowa State University Extension) and frost-tolerance groupings (University of Maryland Extension):

Crop	Days to maturity	Frost tolerance
Radishes	25–40	Light frost
Arugula	Fast	Hard frost
Spinach	45–60	Hardy (withstands a hard frost)
Leaf lettuce	45–60	Light frost
Turnips	45–70	Hardy
Mustard greens	Fast	Light frost
Swiss chard	60–65	Light frost
Beets	50–70	Light frost
Carrots	60–80	Light frost; sweeten in the ground

Get Your Seed Supply Sorted First

A fall sowing is only as good as the seed you put in the ground, and this is a moment where buying open-pollinated, heirloom varieties pays off twice. First, heirlooms are the proven cold-season workhorses — the spinaches and kales that have been overwintered by gardeners for generations. Second, because they breed true, you can let a few plants go to seed next spring and save your own, turning one purchase into a self-renewing supply.

Disclosure: the product links here are affiliate links, so we may earn a commission if you buy through them at no extra cost to you. Our crop and timing guidance follows long-standing university-extension recommendations for fall and cool-season gardening, not brand marketing.

The 9 Cold-Hardy Crops to Sow in Late Summer

1. Radishes. The sprinter of the fall garden. Some varieties are ready in under a month, so you can sneak them in even where fall comes early — and where you’re waiting on slower crops, they make a fast, satisfying first harvest.

2. Arugula. Quick, peppery, and genuinely cold-loving. Arugula germinates and grows fast in cooling soil, tolerates hard frost, and keeps producing cut-and-come-again leaves for weeks.

3. Spinach. The champion of cold-hardy greens. Spinach thrives as the weather cools and withstands a hard frost (University of Maryland Extension). Its one quirk is that high soil temperatures can hold back germination (Iowa State University Extension), so shade the bed and keep it moist (more on that below).

4. Leaf lettuce. Loose-leaf types mature in as little as 45 days and taste sweeter in cool weather. Sow in the shadiest part of the bed for late-summer sowings, since hot soil can inhibit germination.

5. Turnips. A two-for-one crop — tender greens in a few weeks and sweet roots by fall. Turnips are hardy, fast, and forgiving, and they hold well in the ground once the weather turns cold.

6. Mustard greens. Fast, frost-tolerant, and full of flavor, mustards are a cool-season staple across the South and beyond. They bolt in heat but come into their own as the days shorten.

7. Swiss chard. One of the most productive and forgiving greens you can grow. Chard sown now keeps cutting into the cold, tolerates frost, and often overwinters in milder zones to leaf out again in spring.

8. Beets. Sow now for a fall dig. Beets give you edible greens along the way and sweet roots that actually improve in cool soil. Keep the seed bed damp until the seedlings are up — beet “seeds” are seed balls with several embryos, so plan to thin, and they need steady moisture (University of Maryland Extension).

9. Carrots. The crop most worth the wait. Carrots left in the ground through light frosts turn noticeably sweeter (Illinois Extension). Sow now, keep the surface moist until germination (the slowest step), and dig into late fall.

Getting Late-Summer Seeds to Germinate

Sowing in warm soil is easy; germinating in warm soil is the real challenge, because hot, dry ground kills seeds before they sprout and bakes a crust that seedlings can’t push through. Three habits solve it:

• Keep the seed bed consistently moist. Warm soil dries fast, so light watering once or twice a day until the seedlings emerge makes the difference between a full stand and a patchy one.
• Improve the soil’s water-holding first. Working a hydrated coco coir brick (Amazon) into the top inch or two of the bed helps it hold moisture between waterings and keeps that germination crust from forming. Coir is near-neutral to slightly acidic (pH 5.5–6.8) and holds 5–7 times its weight in water once rehydrated (UC ANR) — ideal for a late-summer seed bed.
• Shade the bed. A layer of floating row cover or shade cloth cuts the harshest afternoon sun, lowers the soil temperature into the range where cool-season seeds will actually sprout, and doubles as pest protection for tender fall greens.

Sow a little deeper than you would in spring so seeds sit in cooler, moister soil, and water in the early morning so plants are hydrated before the day’s heat peaks.

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Beyond Vegetables: Cold-Hardy Medicinal Herbs

A self-reliant fall garden isn’t only about food on the plate. Late summer is also a window to start medicinal herbs such as calendula, chamomile, echinacea, and yarrow. A ready-made Medicinal Garden Kit (Amazon) bundles the seeds for a starter apothecary bed, so the same trip to the garden that fills your kitchen also stocks the salves, teas, and remedies side of self-reliance.

Tuck a few of these along the edges of your fall beds where they’ll get established before winter and return, in many cases, for years.

Protect the Back End of the Season

Everything you sow now can be pushed weeks later into the cold with a little protection once hard frost arrives. Floating row cover is the fast, cheap way to shield whole beds — our step-by-step guide to using row covers for fall frost protection walks through choosing the right weight and installing it. For a small patch of winter greens, our DIY cold frame guide shows how to build one cheaply, and our roundup of row covers vs. cold frames helps you decide which fits your garden.

Sow Now, Eat Into Winter

Late-summer planting is one of the highest-return moves in the backyard-food calendar: it turns the “off-season” into a second harvest and keeps fresh food coming when the neighbors’ gardens are done. Do the frost math, sow a mix of fast greens and longer roots, and keep the seed bed cool and moist while it establishes.

If you’re planning the whole arc of the season, our guide to what to plant in July for a fall harvest covers the earlier window, and the same beds you fill now are the ones you’ll build up for next year. Get these seeds in the ground this week, and fall takes care of itself.