13 Vegetables You Should Never Winter Sow

Gardening in mid-latitude climates with cold winters has its drawbacks. We can’t enjoy long growing seasons like our neighbors to the south. We also have to wait a long time to start our seeds outdoors. 

That’s where winter sowing comes in. Winter sowing is when you start your seeds outdoors early in mini greenhouses such as clear milk jugs or recycled containers. It cold-hardens your seeds and gets them ready for growing outside. 

As useful as it is for many plants, some plants can’t handle it, especially delicate vegetables. These delicious yet cold-sensitive plants won’t germinate unless their sowing conditions are perfect. They need the predictable warmth and light they get from starting indoors or outdoors in the late spring. 

If you sow these delicate vegetables outside this winter, you probably won’t see any seedlings. Below are the 13 warm-weather vegetables you should never winter sow. 

Pumpkin

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Bell Pepper

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Sweet Bell Blend Sweet Pepper Seeds

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Amaranth

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Burgundy Amaranth Seeds

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Sunflowers

	botanical name Helianthus annuus
	sun requirements Full sun
	height 2-12’
	hardiness zones 2-11

Sunflowers are the symbol of summer in many gardens. They’re easy to grow and only take around three months to flower. They have a sensitive taproot that won’t tolerate transplanting or being disturbed. They also need warm weather to germinate. 

According to some studies, they have the highest germination rates in temperatures around 77°F (25°C). Some varieties can stand a light, late-season frost but most need a completely frost-free environment before they germinate. 

These plants produce edible seeds and giant florets that brighten up your garden. Skip the winter sowing and directly sow them outdoors when the temperatures get warm. If you live in very cold climates, such as zone 2, you can try starting them indoors under grow lights. 

Tomatoes

	botanical name Solanum lycopersicum
	sun requirements Full sun
	height 2-8’
	hardiness zones 3-11

Tomatoes are one of the world’s most planted and enjoyed edible plants. Although they’re considered vegetables, they’re technically fruits and members of the nightshade family of plants, which include eggplants and potatoes. They thrive in warm summer gardens, providing bountiful harvests of bright red fruit. 

These plants are native to the warm climates of coastal South America. Thousands of years ago, they spread through Central America. Because of their natural distribution, they love warm weather. Their seeds don’t need cold stratification to germinate. 

Although some gardeners have been able to winter sow tomatoes, you’ll be far more successful starting these famous vegetables indoors. Tomatoes grow as perennials in tropical climates, but in cold climates they are annuals. Their seeds need hot weather and soil temperatures of 60°F (16°C) or above. 

Bell Peppers

	botanical name Capsicum annuum
	sun requirements Full sun
	height 1-2’
	hardiness zones 4-11

Bell peppers are another warm-weather crop that you should never winter sow. Although some varieties can germinate in cooler weather, most won’t survive the cold. Like other chilis, these sweet and juicy peppers were first cultivated in tropical regions of Mexico and Central America. 

Most bell peppers need a growing season of 3 or 4 months with temperatures above 50 or 60°F (10 or 16°C). If you live in cold climates such as Minnesota and Maine, this is sometimes difficult. In these climates, don’t winter sow; instead, start these vegetable seeds indoors. 

Bell peppers are easy to grow indoors and transplant once the weather warms up outside. If the soil is warm enough, you’ll see seedlings appear in 7 to 14 days. 

Cucumbers

	botanical name Cucumis sativus
	sun requirements Full sun
	height Up to 8’
	hardiness zones 2-11

Cucumbers are one of the best summer crops. They grow vigorously once the weather is warm and need very little maintenance. If the climate is right, you’ll enjoy bountiful harvests throughout the summer. 

As easy as they are to grow, cucumbers are very cold-sensitive. They’re native to the Indian subcontinent, in areas with warm summers and short, mild winters. They need warm, humid conditions and soil temperatures around 70°F (21°C) to germinate. 

Because of their intolerance to cold, they are poor contenders for winter sowing. If you try, you probably won’t see any germination. Some seeds will last through the cold and germinate once the weather warms up. If you live in cold climates, try starting them indoors on a seedling heating mat. 

Zucchini 

	botanical name Cucurbita pepo
	sun requirements Full sun
	height 2-4’
	hardiness zones 3-11

Like other summer squash, zucchini needs bright warm sunshine and warm temperatures to germinate. These squash varieties evolved on the warm slopes of the Andes and the hills of Central America. Because of this, their seeds need warm soil to germinate. 

Sow when the soil temperatures are between 70 and 90°F (21 and 32°C). If you plant them when the ground and air are still cold, they won’t germinate successfully. If there’s a late frost, you can lose your plants; do not winter sow these warm-weather vegetables.

In USDA zones 5 and colder, consider starting them indoors. You’ll want to be careful in the process of transplanting zucchini starts. This is because they sometimes succumb to transplant shock.

Eggplants 

	botanical name Solanum melongena
	sun requirements Full sun
	height 1-3’
	hardiness zones 9-12

Eggplants are another species in the nightshade family that loves growing in warm soil. Like many other vegetables on the list, they’re technically a fruit but considered a vegetable for culinary purposes. 

They originated in tropical Asia and Africa and have been cultivated for thousands of years. They thrive in warm, tropical regions or warm summer gardens as annuals. 

To get them to germinate, you’ll have to wait until the soil is above 80°F (27°C). If you’re a cold-climate gardener, break out the seedling heating pads and start them indoors. After 6 to 7 weeks, your plants should be ready for the outdoors as long as the risk of frost has passed. Make sure to harden off your plants by slowly acclimating them to the outdoors. 

Corn 

	botanical name Zea mays
	sun requirements Full sun
	height 5-8’
	hardiness zones 2-11

Corn is one of the most popular summer crops. It’s native to the Americas where it’s a staple ingredient in cuisines from Patagonia to Canada. Although the plant grows in cold climates, it needs warm temperatures to germinate. 

The soil has to be over 60°F (16°C) for the seedlings to emerge. Corn grows fast, so in most climates, direct sowing is easy to do as late as May or June. Most varieties of seedlings will die if they experience sub-zero temperatures. 

Try sowing your corn in late spring or early summer and you’ll enjoy tons of juicy ears by summer. Try growing multiple varieties, including sweet corn and multicolored heirlooms. 

Okra 

	botanical name Abelmoschus esculentus
	sun requirements Full sun
	height 3-8’
	hardiness zones 2-11

Okra is one of the world’s oldest crops, with evidence of cultivation going back thousands of years to ancient Egypt. It spread throughout Africa, Asia, and Europe to become a staple in stews and soups. In the American South, it’s easy to find a restaurant with fried okra or okra gumbo. 

To grow okra successfully, don’t even try winter sowing. The plant needs warm soil and frost-free air to germinate. If you’re living in a cold climate, you’re better off starting your okra seeds indoors long before the last frost. 

Once the temperature outside remains above 70°F (21°C), move your seedlings outdoors. Harden them off first to acclimate them to the outside environment and light intensity. If you do this successfully, your okra plants will produce big, green pods that are full of nutrients and flavor!

Pumpkin 

	botanical name Cucurbita pepo
	sun requirements Full sun
	height Up to 20’
	hardiness zones 3-11

Although pumpkins are considered winter squash, they need plenty of heat to germinate. They take around 80 to 120 days to mature and produce fruit. For some varieties, you’ll need almost 150 days!

Because of the long time it takes to mature, many gardeners try to winter sow these nutritious vegetables. However, you’ll likely fail if you expose these seeds to temperatures below 60°F (16°C) prematurely. If you live in cold climates, start your seeds indoors and use a seedling heating mat to warm up the soil. 

If you have long summers, go ahead and sow directly outdoors. Wait until the soil is over 70°F (21°C). If it’s below 65°F (18°C), your pumpkins will not germinate. If there’s a risk of a late-season frost or cold snap, try protecting your plants with row covers. 

Sweet Potato 

	botanical name Ipomoea batatas
	sun requirements Full sun
	height 6-15′
	hardiness zones 9-11

Sweet potatoes are marvelous vegetables that are full of nutrients and flavor. If you’ve never tried growing them, you should! They’re easy to grow and produce bounties of wonderful root vegetables full of nutrients and antioxidants. They are some of the oldest cultivated vegetables in the world and are fun to grow in many climates in the US. 

These plants love growing in warm soils. They’re annual crops in zones 5-9 but perennial in tropical regions. They’re relatives of the Morning Glory family of plants. 

To grow them successfully, try growing them from slips in soil that is over 65°F (18°C). They’ll take root quickly and fill out your garden with beautiful foliage. They need 90 to 150 days to mature and produce their wonderful root vegetables. 

Beans 

	botanical name Phaseolus vulgaris
	sun requirements Full sun
	height Up to 15’
	hardiness zones 2-11

Beans are some of the easiest and most bountiful crops you can grow in your summer garden. They’re native to Central and South America, where they’ve been cultivated for thousands of years. They quickly spread throughout the Americas, becoming one of the biggest staple crops for many early societies. Once the Europeans brought them to Europe, they quickly spread throughout the world. 

These tasty and nutritious legumes contain tons of protein. Once you dry them, you can store them in jars for several seasons. When you’re ready to use them, soak them in water overnight and boil them until they’re soft. 

Although they can tolerate some cold temperatures, they need warm soil to germinate. Plant them after the soil temperature is above 60°F (16°C). Make sure not to plant them too late because excessive heat will kill their flowers. If you live in a cold place, try starting them by seed indoors. 

Bitter Melon 

	botanical name Momordica charantia
	sun requirements Full sun to partial shade
	height Up to 20’
	hardiness zones 9-11

If you’ve never tried growing bitter melon, you’re in for a treat. This vine produces tasty green fruits that are treated like vegetables in many cuisines around the world. The plant is native to Asia and is grown throughout the tropics. 

It has a slightly bitter flavor and contains tons of nutrients. It grows quickly, so if you’re growing it as an annual in colder regions, you should have a bountiful harvest throughout the summer. 

To grow bitter melon, sow your seeds when the soil is over 70°F (21°C), long after the threat of frost has passed. Frost will quickly kill this tropical vine’s seedlings. 

Amaranth 

	botanical name Amaranthus viridis
	sun requirements Full sun
	height 2-3’
	hardiness zones 7-11

Amaranth is an ancient American grain that is a treat to grow. You can grow the plants for their seeds, which produce nutrient-dense grains with rich flavors. You can also eat the leaves and use them in stews or salads if they’re young.