March 20 marked the first day of spring but with the fluctuations in temperature some days haven’t felt very spring like. I was curious about what the soil temperature was, so I went out this morning while the sun was shining and checked the raised beds at the office, and they were 50 degrees. I then checked several of the flower beds and even the yard and they too were 50 degrees.
Don’t let these warm days fool you into planting your garden too early. The frost-free date for Morrow County is May 2nd, but I would caution folks about planting crops out that like warm weather this early. There is always a possibility that we could get another frost before Mother’s Day and even after. I like to plant my warm season crops around Memorial Day. If you have the garden itch there are some flowers and vegetable crops that do like cooler weather. Cool season annual flowers include primrose, pansies, snap dragons and marigolds, just to name a few. Cool season vegetables include broccoli, brussels sprouts, cabbage, beets, spinach, and carrots and those can germinate in 40 degree soil temperatures, however many of our warmer season crops like the soil to be around 55 - 60 degrees or even warmer. The same temperatures should also be used when planting transplants outside.
Air temperature also needs to be kept in mind. If there is a threat of heavy frost or freeze, cover your plants with cloth, not plastic, unless the plastic isn’t touching the plant, if it is the plant will freeze. Also keep in mind if it's cold and damp, seeds that have not yet germinated might rot. Once they do germinate the small seedlings could rot from being too cold and wet.
Another garden task that many folks get excited about doing, is applying mulch. Mulch ideally should not be applied to garden beds until your perennial plants start to wake up and the soil temperatures are around 60 - 65 degrees, sometime in late April or May depending on where you live.
Consistent weather will be here before we know it, but until then refrain from applying mulch to cold wet soils and from planting those warm season annuals and vegetables in cool damp soils.
I challenge you to measure your soil temperature and let me know how warm it is at jagger.6@osu.edu.
