Cool-Season vs. Warm-Season Crops: Calendar Differences

Every crop falls on a spectrum between loving cool weather and needing real heat. Where it sits decides where it goes on your calendar.

Key points

Cool-season crops tolerate frost and cooler soil; warm-season crops do not.
Place cool-season crops in spring and fall, warm-season crops after frost.
Heat can bolt cool-season crops, and cold can stall warm-season crops.
Use soil temperature to set both lists.

What separates cool-season from warm-season crops?

Cool-season crops, including lettuce, spinach, peas, brassicas and root crops, germinate and grow in cooler soil and tolerate light frost, and many do best in mild weather. Warm-season crops, such as tomatoes, peppers, squash, cucumbers, beans and corn, need warm soil and frost-free nights and slow or stop when it is cold.

The difference comes from physiology, and it shows up in the minimum soil temperatures listed on charts. One Wisconsin chart lists minimums around 45 degrees Fahrenheit for lettuce, carrots and beets, and 65 to 72 for peppers, cucumbers and beans.

The two groups also differ in their best use of space. Cool-season crops occupy a bed for a short spell in spring and fall, while warm-season crops hold a bed from early summer to frost.

Where do cool-season crops go on the calendar?

They go in early spring, as soon as the soil can be worked, and again in late summer for fall harvest. Many handle light frosts, and some taste better after cold weather. A few, like garlic, are planted in fall for harvest the next summer, which depends on your region.

In a hot summer climate, they may need to go in during fall, winter or very early spring so they finish before heat arrives.

Soil workability matters too. Wet, heavy ground in early spring tears and clumps when worked, so wait until it crumbles in your hand.

Early spring sowing.
Late summer sowing for fall.
Fall sowing in mild climates.

Where do warm-season crops go?

They go in after the last frost has passed and the soil has warmed to their minimum. Tender transplants are set out once nights are consistently warm. Direct-sown warm-season seeds, like beans and squash, wait for warmer soil than many people expect.

A late planting is better than a cold one, since warm-season crops planted into cold soil may stall, rot or carry stress that holds them back for weeks.

Some gardeners wait for a stretch of warm nights as well as warm soil before setting out tender transplants, because chilly nights slow growth even without frost.

How does heat affect cool-season crops?

Hot weather makes cool-season crops bolt, turn bitter or fail to germinate. The University of Illinois Extension notes that crops such as broccoli, lettuce, carrots and snap peas can turn bitter in higher temperatures. University of California material adds that lettuce seed germinates poorly in hot soil.

Plan harvests before heat arrives, and give shade or a break from sowing in the hottest weeks.

Shade cloth, mulch and steady watering help cool-season crops hang on through a warm spell, though they cannot stop bolting once heat arrives for good.

How does cold affect warm-season crops?

Cold nights and cold soil slow growth, and frost can kill tender plants. Even above freezing, chilly weather can set back crops such as peppers and tomatoes. Protect with row cover on cold nights, and delay planting when a cold spell is in the forecast.

For example, if your transplants are ready but a cold snap is coming, hold them in a sheltered place instead of setting them out.

Plastic mulch, row cover and a sheltered location can help warm-season crops through a cool spell, but they cannot make up for planting into cold soil.

How do you schedule both on one farm?

Make two lists. Put cool-season crops in the shoulder seasons, and warm-season crops in the middle of the season. Use the same bed for a cool-season crop in spring and a warm-season crop in summer, or a cool-season crop again in fall.

Match each crop to a window defined by frost dates and soil temperature, and not by a calendar date from another region.

What mistakes should you avoid?

Planting warm-season crops too early because of a warm week is the most common. Another is leaving cool-season crops to face midsummer heat. A third is assuming one crop's rule applies to all in a family.

Check each crop's chart. Within brassicas, for instance, tolerance to heat and cold differs a lot by type.

Keep a list of crops that did well and poorly in each season. A cool summer may favor cool-season crops, and a hot one may do the opposite. Use the pattern to adjust next year's mix.

When to get local help: Your county extension office can give you the crop lists and soil temperature minimums that fit your area.

Sources and further reading

Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.

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