The best time to plant tomatoes in Iowa is typically after the danger of frost has passed, which aligns closely with Mother's Day, around early to mid-May. This timing is when nighttime temperatures consistently stay above 50°F and soil temperatures reach at least 60°F during the early morning. Tomatoes need warm soil and air temperatures to grow well and will not thrive if planted when temperatures are too low. Specifically:
- Central Iowa gardeners often plant tomatoes anytime after Mother's Day (around May 8-14), when the chance of frost nears zero.
- Soil temperature should be at least 60°F, which usually occurs by mid-May.
- Nighttime temperatures should stay consistently above 50°F.
- The last practical planting date for good yields is around June 20.
- Southern Iowa can start planting tomatoes outdoors in late April, while northern counties should wait until mid-May.
Additional tips include planting tomatoes deep to encourage root growth and waiting if the weather forecast predicts significant cold or frost protection is needed. So, for Iowa, aim to plant your tomatoes in early to mid-May, monitoring soil and nighttime temperatures for the best results.
