Summer may be in full swing, but that doesn’t mean it’s too late to plant. In fact, several crops thrive in the heat and mature quickly enough to beat fall frost, even when started in June or July. Whether you’re filling empty rows or just getting started, these heat-tolerant vegetables, herbs, fruit, and flowers are reliable performers—all available from St. Clare Heirloom Seeds.
Table of Contents
Here are 11 crops you can still plant from seed during the hottest part of the growing season.
1. Okra
Days to Maturity: 50–60 days
Okra thrives in the heat and is practically made for July planting. Varieties like Clemson Spineless and Red Burgundy grow quickly and produce tender pods perfect for frying, stews, or pickling. Okra needs full sun and warm soil to germinate, and the more you harvest, the more it produces.
Tip: Soak seeds overnight before planting to speed germination. Harvest pods when 3–4″ long for best texture.
2. Cowpeas (Southern Peas)
Days to Maturity: 60–70 days
Also known as black-eyed peas or cream peas, cowpeas handle heat, humidity, and even drought. They’re ideal for the Southeast, lower Midwest, and southern Plains. They fix nitrogen in the soil and can be used green or dry.
Tip: Direct sow in full sun. Bush types are best for quick harvests; trellis vining types if space allows.
3. Basil
Days to Maturity: 45–60 days
Basil loves summer heat and grows fast from seed. Genovese, Lemon, and Thai basil varieties from St. Clare are all quick to germinate and productive through hot weather. Regular harvesting delays flowering and boosts yield.
Tip: Sow in succession every few weeks for fresh leaves through fall. Pinch flower heads to keep leaves coming.
4. Malabar Spinach
Days to First Harvest: 55–65 days
While not a true spinach, Malabar spinach is a vining green that thrives in tropical heat. It’s perfect for southern zones and humid climates where leafy greens usually fail. The leaves can be eaten raw or cooked and continue growing until frost.
Tip: Provide a trellis and harvest young leaves regularly. In cooler zones, start seeds indoors to get a jump.
5. Lemon Queen Sunflower
Days to Bloom: 70–80 days
This fast-growing heirloom sunflower not only tolerates heat, it loves it. Lemon Queen grows quickly and flowers by early fall if planted mid-summer. It’s a favorite of pollinators and adds cheerful, golden color to any garden bed.
Tip: Sow directly in full sun. Space 12–18″ apart. Water until established, then it’s drought-tolerant.
6. Black Beauty Zucchini
Days to Maturity: 50–60 days
Zucchini may struggle in late summer due to squash bugs and borers—but fast-growing Black Beauty gives you a shot at a strong harvest before pests peak. When planted in June or July, it often avoids early-season pest pressure and still yields heavily.
Tip: Sow directly in warm soil and harvest fruits at 6–8″ for peak flavor. Mulch to conserve soil moisture.
7. Crimson Sweet Watermelon (for Warmer Zones)
Days to Maturity: 80–85 days
If you’re in Zones 6b or warmer, you can still start a late crop of watermelon. Crimson Sweet matures in about 80 days and is known for sweet, juicy flesh and heat tolerance. It needs space and sun, but rewards the effort with a late-summer harvest.
Tip: Start with pre-warmed soil and keep vines evenly watered. In Zones 5–6a, try a smaller variety like Sugar Baby (75 days).
8. Lacinato Dinosaur Kale
Days to Maturity: 65–75 days
Also known as Tuscan or Dinosaur Kale, this Italian heirloom produces dark, blue-green leaves with a crinkled texture and rich, earthy flavor. Though often grown for fall, Lacinato kale can be sown in midsummer for a fall harvest and tolerates heat surprisingly well when given consistent moisture and some afternoon shade. It’s slow to bolt and grows upright, making it great for smaller gardens.
Tip: Sow directly or transplant starts about 8 weeks before your first expected frost. Mulch well to retain moisture and harvest the outer leaves when 8–10″ long. Plants become sweeter after light frost.
9. Green Wave Mustard Greens
Days to Maturity: 45–55 days
A fast-growing Southern favorite, Green Wave mustard greens are highly heat-tolerant and slow to bolt, making them ideal for midsummer sowing. Their frilled, bright green leaves pack a peppery bite raw and mellow out when cooked. This heirloom performs reliably in both hot and cool weather, offering flexible timing for multiple harvests.
Tip: Sow directly in full sun or partial shade. For continuous harvest, sow every 2–3 weeks. Pick young leaves often to encourage new growth and keep plants tender.
10. Red Garnet Amaranth
Days to Maturity: 40–60 days for greens
Amaranth thrives in high heat and poor soil, making it one of the best leafy greens for summer planting. Red Garnet produces vivid reddish-purple leaves that can be harvested young for salads or cooked like spinach. Left to grow, the plants develop tall, dramatic flower spikes and edible seeds by fall.
Tip: Sow seeds directly in warm soil and do not cover deeply—they need light to germinate. Harvest baby leaves regularly or let some plants mature for ornamental seed heads.
11. Champion Collard Greens
Days to Maturity: 60–80 days
Collards are known for their hardiness, and Champion is especially valued for its heat tolerance and bolt resistance. This variety produces broad, blue-green leaves with a mild flavor, perfect for sautéing, braising, or chopping into soups. Summer-sown collards mature in fall and improve in taste after a light frost.
Tip: Direct sow in mid to late summer for a fall crop. Space plants well and keep evenly watered for best growth. Harvest outer leaves as needed for continuous yield.
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Bonus Tip: Choose Fast-Maturing Varieties
When planting heat-tolerant crops in midsummer, timing is everything. Even the most heat-loving crops need to mature before fall frost, so choosing varieties with short growing seasons is key. Focus on crops that mature in under 80 days, with some like basil, okra, and zucchini ready in as little as 50–60 days. This gives you flexibility even in regions with shorter summers.
Look for heat-tolerant varieties with a short season, and don’t overlook crops that can be harvested at different stages—for example, squash picked young or greens harvested continuously. In colder zones (like Zones 4–6), that extra buffer between maturity and frost is critical.
Starting with warm soil, full sun, and regular watering will help you hit maturity dates more reliably. With fast-maturing seeds and a bit of planning, you’ll beat the heat and the frost.
Tips for Growing in Summer Heat
- Choose heat-tolerant varieties: Opt for varieties specifically bred or known for their heat tolerance.
- Provide shade: Especially during the hottest part of the day, provide some shade to prevent wilting.
- Water regularly: Ensure consistent moisture, as heat can cause plants to dry out quickly.
- Mulch: Mulching helps retain soil moisture and keeps roots cool.
- Succession planting: Sow seeds every few weeks to ensure a continuous harvest, especially for quick-growing greens.
Final Word: High summer is far from the end of gardening—it’s an opportunity. This time of year can be ideal for squeezing in a quick second crop, reviving worn-out beds, or experimenting with new varieties that thrive in heat. Even small successions—just a few rows of basil or a patch of okra—can yield a surprising amount of fresh food before fall. Many of these heat-tolerant crops also face fewer pest issues than those planted in spring.
Gardening in midsummer can feel different—faster paced, more intentional, and deeply rewarding. Whether you’re in the Deep South, Midwest, or high-altitude West, there’s still time to grow something flavorful, beautiful, and productive before frost. Browse our seeds at St. Clare Heirloom Seeds and get planting. It’s not too late!
What are your thoughts? Drop a comment below!
FAQ:
Can I really start seeds in July or August and still get a harvest?
Yes! Many heat-tolerant crops—like okra, basil, zucchini, and mustard greens—mature in under 60 days and can be sown in mid to late summer and harvested before the first frost.
How do I know if a variety is heat-tolerant?
Look for varieties labeled as “heat-tolerant,” “slow to bolt,” or that originate in warm climates. The varieties featured in this article are specifically chosen for their performance in summer heat.
What’s the best way to keep seeds from drying out during germination in hot weather?
Keep the soil consistently moist by watering daily (sometimes twice a day during extreme heat). Use a light layer of mulch or shade cloth to reduce evaporation and prevent crusting.
What zone do these recommendations apply to?
These crops are adaptable across most U.S. zones. Some (like watermelon or Malabar spinach) are best suited for Zones 6 and up, but most options will thrive anywhere summer heat is present.
Can I grow leafy greens in summer?
Yes—if you choose heat-tolerant greens like Malabar spinach, amaranth, mustard greens, kale, and collards. These varieties won’t bolt as quickly and can be harvested repeatedly.
Do I need to start these indoors or can I direct sow?
Most of these crops can be direct-sown into warm soil. In northern zones or for longer-maturing crops like kale and collards, you may choose to start indoors for a head start.
How often should I water in summer?
Generally, water deeply 2–3 times a week, but daily watering may be needed during heatwaves or when establishing seedlings. Mulching helps reduce the frequency by holding in moisture.
How late in the season can I plant?
Count backward from your average first frost date using the crop’s maturity time. For example, if your first frost is October 10 and a crop takes 60 days to mature, plant by early August.
Will these crops grow in containers?
Yes—many of them can. Basil, mustard greens, kale, and even dwarf okra can do well in large pots. Just be sure containers are deep enough, don’t dry out too fast, and are placed in full sun.
Should I fertilize summer plantings?
Yes. Fast-growing summer crops benefit from a balanced fertilizer or compost-enriched soil. Greens especially need nitrogen, while fruiting crops like zucchini and watermelon benefit from phosphorus and potassium as they begin to flower.
