Springing Towards the Growing Season!

Spring is in the air and it’s time to get our hands dirty! It might feel strange to start thinking about gardening with the amount of moisture we have received this month, and the chilly mornings. However, soil temperatures in Iowa are 32 degrees or higher. Both soil and air temperatures can affect plant life and germination of seeds. If too cold or too warm they can cause problems with seed germination and plant growth. It is important to check on temperatures throughout the season to ensure that you have a successful harvest!

Master Gardener in Garden

With soil temperatures in the upper 30s and air temperatures in the mid-40s or higher it is safe to start planting your cool-season plants. Cool-season plants are able withstand the cooler temperatures we have in early spring, or even late fall. As soon as you can work the soil, you can sow your cool-season seeds! Some cool-season crops that are common in many Iowa gardens would be: radish, lettuce, onions, peas, spinach, cabbage, broccoli, cauliflower, collards, kale, carrots, beets, chard, and Brussel sprouts. Warm-season crops require a warmer soil and air temperature to be successful. You’ll want to wait until the air temperatures are in the 60s before planting. Warm-season crops that are common would be: corn, peppers, eggplant, zucchini, beans, melons, cucumbers, pumpkin, squash, and tomatoes.


Cool-season crops can be planted during spring and mid-summer. They can expand your harvest throughout the growing season. Warm-season crops are typically harvested once during a growing season. Gardeners like to harvest their cool-season crop with a warm-season crop when they are harvested to save space in their garden.


For more information about planting and harvesting times from ISU Extension and Outreach’s publication called “Planting and Harvesting Times for Garden Vegetables”. This publication can be found on the Extension Store. You can also learn more about cool-season vs. warm-season crops in the Iowa Master Gardener program that will begin in the fall. For more information and registration visit: https://www.extension.iastate.edu/news/registration-open-fall-master-gardener-training-1.


Katelyn Brinkerhoff

Horticulture Educator
Iowa State University Extension and Outreach—Woodbury County