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Garden plant growing in the soil

When warm weather arrives we’re eager to begin cultivating this season’s crops. However, it is soil temperature rather than air temperature that controls seed germination. Planting at the optimal temperature for a specific crop is the best practice to ensure production of hearty seedlings.

 

Soil Temperature Conditions for Vegetable Seed Germination

VegetableMinimum (°F)Optimal Range (°F)Optimum (°F)Maximum (°F)
Asparagus5060–857595
Bean, lima6060–858585
Bean, snap 6065–858095
Beet4050–858585
Cabbage4045–9585100
Carrot4045–858095
Cauliflower4045–8580100
Celery4060–707085
Chard, Swiss40 50–858595
Corn5060–9595105
Cucumber6060–9595105
Eggplant6075–908595
Lettuce3540-807585
Muskmelon (cantaloupe)6075–9590100
Okra6070–9595105
Onion3550–957595
Parsley4050–857590
Parsnip3550–706585
Pea, English4040-757585
Pepper6065–958595
Pumpkin6070-9090100
Radish4045–908595
Spinach 3545-757085
Squash6070–9595100
Tomato5070–958595
Turnip4060–10585105
Watermelon6070–9595105

 

Soil temperatures should be taken by inserting a soil thermometer 3 to 4 inches deep into the soil surface and noting temperature. Soil thermometers are available from garden centers, feed and seed stores, and many garden supply catalogs. Soil temperatures should be consistent for several days before seeds are sown to ensure that the seeds are being exposed to optimal temperatures for germination.

Download a PDF of Soil Temperature Conditions for Vegetable Seed Germination, ANR-1061. 

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