Minimum Temperatures For Transplanting And Sowing Vegetables And Flowers

Question From: M. Berna - ILLINOIS
Q: Hi Nancy, today I transplanted some veggie and flower seedlings from 6 packs into 3" pots. I now do not have room on my "under lights" table for all of them. Is there a grace period that I should follow before I move them into cold frame. Do I harden them off first? I am in zone 5. Thanks. MIKE


Mike, Hopefully you are growing cold weather crops. In my zone 5 the night-time temps are still dropping below freezing on occasion. Your cold frame will have to be in the sun and if it's shinning you will need to open it daily so the plants do not cook. Here are some minimum soil temps for transplants. It's still too cold to plant in my zone 5 Michigan or even put plants out in a cold frame. Hope this helps. Best And Happy Yardening, Nancy

Use the following guide for MINIMUM soil temperatures for transplants:

  • 60° F tomatoes, cucumbers, snap beans
  • 70° F peppers, watermelons, squash
  • 75° F cantaloupe, sweet potatoes

Temperature is also an important factor for direct sowing crops. Measure at a depth of one to two inches when you are not transplanting. Here are the MINIMUM soil temperatures for vegetables that are direct sowed:

  • 35° F lettuce, spinach and other salad greens
  • 40° F peas
  • 45° F radishes
  • 50° F onions, beets, Swiss chard
  • 60° F beans, snap and dry, corn
  • 70° F beans, lima