You should not plant in fall any warm-season crops that need heat and long sunny days to thrive. Tomatoes, peppers, cucumbers, and squash all fail when planted as temperatures drop and daylight shrinks. Save your seeds and effort for cool-season vegetables instead.
I learned this the hard way when I tried planting tomato transplants in late August one year. The plants looked healthy at first but stopped growing once nights turned cool. They set a few flowers but never made a single ripe tomato before frost killed them off in October.
Vegetables to avoid fall planting share common traits that explain their failure. They need soil temps above 60°F (15.5°C) to grow roots and absorb nutrients well. They also need 8 or more hours of direct sun to produce fruit and ripen their harvest on time.
Fall conditions work against warm-season crops in two ways. First, soil cools down as air temps drop, slowing growth to a crawl. Second, daylight hours shrink each day, cutting the energy plants need to make fruit. Even a warm fall can't give these crops what they require.
Fruiting Vegetables
- Tomatoes: Need 3-4 months of warm weather and won't ripen in cooling fall temperatures.
- Peppers: Stop setting fruit below 60°F (15.5°C) and drop flowers when nights get cold.
- Eggplant: Requires constant warmth and gives up fast when temps start falling in autumn.
Vine Crops
- Cucumbers: Quick to die at first hint of frost and need warm soil for germination to work.
- Squash: Both summer and winter types need months of heat to produce a decent harvest.
- Melons: Require the longest warm season of any vegetable and fail in fall conditions.
Other Heat Lovers
- Corn: Needs warm soil to sprout and requires 60-100 days of summer heat for ears.
- Beans: Struggle in cool soil and won't germinate when temps drop below 60°F (15.5°C).
- Okra: Loves extreme heat and stops producing when nights cool down in early fall.
Know what not to grow autumn by checking seed packets for temperature needs. Any vegetable that lists warm soil or full sun for most of the day belongs in your spring and summer garden. Fall gardens work best with crops that prefer cooler conditions.
Warm season crops fall into failure mode when you plant them too late. Peppers I planted in September just sat there for weeks doing nothing. They never grew another inch and looked sad until frost ended their misery. That wasted space could have grown loads of lettuce instead.
Focus your fall planting energy on vegetables that thrive in cool weather. Lettuce, spinach, kale, and radishes all prefer the conditions that warm-season crops hate. You'll get better results with less effort by working with the season instead of fighting against it.
Some gardeners try to extend warm-season harvests with row covers and cold frames. These tricks work for protecting plants that started earlier in the season. They won't help new plantings that need months of heat to reach harvest size before winter arrives.
Save your tomato and pepper seeds for spring when conditions match what they need. Your fall garden will produce more food when you fill it with crops suited to the season. Cool-weather vegetables taste better in fall anyway since frost makes many of them sweeter.
Read the full article: When to Plant Vegetable Garden: Ultimate Guide
