Jacki Cammidge is a Certified Horticulturist specializing in frugal, low-input gardening and propagation, with lifelong hands-on experience and years as a wholesale nursery head propagator.

Soil Temp For Seed Planting

Out of all The Factors, This is One to Get Right For The Plants You're Growing

Best soil temperature for germination for different crops varies according to their needs. Warm weather plants, like tomatoes or peppers, require a lot warmer soil than something in the brassica family, or peas which prefer it much cooler.

Growing plants from seed indoors to get the seedlings to a good size to transplant outside when the weather warms will mean getting a few supplies.

Your soil mix, of course, and a watering can or sprayer to start, and one thing in addition; a soil thermometer so you can figure out what the seeds really need to germinate, as well as using it to tell you the soil temperature outside in the garden.

Air temperature and soil temperature are two different things. It will take the soil a lot longer to heat up than a few warm days.

If it's still chilly at night then the soil will also remain cool, too cool to plant out many seeds. The problem is that in cooler soil temperatures the seed will rot.

Here’s a simple planting guide by crop and season, based on soil temperature for germination.

Cool-season crops
Plant when soil is 40–75°F
Best for early spring or fall

- Lettuce: plant at 40°F+, best at 60–75°F
- Spinach: plant at 35°F+, best at 45–75°F
- Peas: plant at 40°F+, best at 45–75°F
- Radishes: plant at 40°F+, best at 50–85°F
- Carrots: plant at 45°F+, best at 55–75°F
- Beets: plant at 45°F+, best at 50–85°F
- Kale: plant at 40°F+, best at 45–85°F
- Cabbage: plant at 40°F+, best at 50–85°F
- Broccoli: plant at 40°F+, best at 50–85°F
- Cauliflower: plant at 40°F+, best at 50–85°F
- Onions: plant at 35°F+, best at 55–75°F
- Parsley: plant at 40°F+, best at 50–70°F
- Cilantro: plant at 40°F+, best at 50–75°F
- Dill: plant at 40°F+, best at 60–70°F

Warm-season crops
Plant when soil is 60–95°F
Best for late spring to summer

- Tomatoes: plant at 50°F+, best at 70–85°F
- Peppers: plant at 60°F+, best at 75–85°F
- Eggplant: plant at 60°F+, best at 75–90°F
- Beans: plant at 60°F+, best at 70–85°F
- Corn: plant at 50°F+, best at 65–85°F
- Cucumbers: plant at 60°F+, best at 70–95°F
- Squash: plant at 60°F+, best at 70–95°F
- Pumpkins: plant at 60°F+, best at 70–95°F
- Melons: plant at 65°F+, best at 80–95°F
- Okra: plant at 65°F+, best at 80–95°F
- Basil: plant at 60°F+, best at 70–85°F

Simple season rule
- Early spring: peas, spinach, lettuce, onions, radishes
- Mid-spring: carrots, beets, broccoli, cabbage, kale
- After frost and warm soil: beans, corn, cucumbers, squash
- When soil is fully warm: tomatoes, peppers, eggplant, melons, okra, basil

Ideal soil temperature for germination depends on the seed, but here are good general ranges:

Warm-season vegetables
- Tomatoes: 70–85°F (21–29°C)
- Peppers: 75–85°F (24–29°C)
- Cucumbers: 70–95°F (21–35°C)
- Beans: 70–85°F (21–29°C)
- Squash: 70–95°F (21–35°C)

Cool-season vegetables
- Lettuce: 60–75°F (16–24°C)
- Spinach: 45–75°F (7–24°C)
- Peas: 45–75°F (7–24°C)
- Carrots: 55–75°F (13–24°C)
- Radishes: 50–85°F (10–29°C)

General rule
- Most seeds germinate best between 65–75°F (18–24°C)
- Cool-season crops can sprout in cooler soil
- Warm-season crops often struggle below 60°F (16°C)

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