The last frost date doesn’t mean plant everything at once. It means the window for your first warm-season crops has opened. These three go in first — before tomatoes, before beans, before squash — and they need to be in the ground within a week of that date to make the most of the season.
Quick Answer
Plant these first: courgettes/summer squash, French beans, and cucumbers — all go in at or just after your average last frost date, once soil has reached 60°F.
Why these three: they mature fastest of all warm-season crops, give you the longest productive window, and are all direct-sown — no transplant shock, no delay.
Wait on: tomatoes, peppers, and aubergines until nights are consistently above 50°F — even a brief cold snap stunts their early growth.
According to Penn State Extension, warm-season crops have a single growing cycle — from late spring after the last frost to late summer — and cannot be replanted if the window is missed. That makes the first week after your last frost date the most critical planting window of the year. The three crops below have the fastest return of any warm-season vegetable, require no indoor head start, and will produce heavily if they go in promptly and at the right soil temperature.
The Three Crops — How to Plant Each One
1 Courgette / Summer Squash
45–55 days1 inch deep24–36 inches
Courgettes are the most productive warm-season crop per plant and reward early planting generously. Sow 2–3 seeds per station, 1 inch deep, and thin to the strongest seedling when true leaves appear. They need full sun and consistent watering once fruit sets — irregular moisture causes blossom end drop. University of Maryland Extension recommends planting 1–2 weeks after the last frost once soil is reliably warm. One or two plants per household is usually sufficient — they produce prolifically from midsummer onwards.
Pick fruits when 6–8 inches long — leaving them to grow larger signals the plant to slow production
2 French Beans (Dwarf or Climbing)
50–60 days1–2 inches deep4–6 inches
French beans are the most straightforward warm-season direct-sow crop. They germinate quickly in warm soil (60°F+), fix their own nitrogen, and need no staking if you choose a dwarf variety. Sow in double rows 6 inches apart for easy picking. Beans will not germinate in cold soil — they rot rather than sprout below 55°F, which is why the last frost date is the correct timing trigger. Old Farmer’s Almanac recommends sowing beans directly after the last frost, succession sowing every two weeks for a continuous harvest through late summer.
Don’t sow climbing beans until you have supports in — trying to add a trellis around established plants disturbs roots and slows growth
3 Cucumbers
50–70 days½–1 inch deep12–18 inches
Cucumbers are the most heat-dependent of the three and are the most sensitive to a late cold snap after planting — but they also reward early placement with the longest productive window. Direct sow 2–3 seeds per station and thin to one. Train them up a trellis or netting from the start; horizontal sprawl takes up bed space that other crops need and makes fruits harder to spot before they overgrow. Once cucumbers start producing, check plants every other day — a missed fruit left to yellow on the vine signals the plant to stop setting new ones.
If a late frost is forecast within 48 hours of sowing, cover with fleece overnight — cucumbers have no frost tolerance at any stage
What to Avoid in the First Post-Frost Week
✗ Common Mistakes
- Planting into cold soil— check temperature at 2-inch depth. Below 60°F, warm-season seeds rot rather than germinate. Wait even if the frost date has passed.
- Transplanting tomatoes too early— tomatoes need nights consistently above 50°F to set fruit. A plant put out too early sulks, goes yellow, and takes weeks to recover even after warming.
- Sowing too many courgettes— one or two plants are enough for a family. Three becomes overwhelming by August.
- Forgetting to water after sowing— warm spring soil dries quickly. Uneven moisture during germination produces patchy stands that are difficult to thin evenly.
📅 First Week After Frost
- Check soil temperature at 2 inches — wait for 60°F
- Sow courgettes, beans, and cucumbers direct
- Erect bean and cucumber supports before sowing
- Water in well; cover with fleece if cold nights forecast
📆 Next 30 Days
- Thin courgettes and cucumbers to one plant per station
- Sow second row of beans 2 weeks after first for succession
- Transplant hardened tomatoes and peppers once nights are reliably warm
- Begin weekly checks for cucumber and courgette fruits