Earlier or later?

May is a month for planting, and most vegetable crops and flowers can now be planted in the garden. However, the timing of when to plant them out is critical. Tender transplants like tomato, pepper, and eggplant may not survive the cold if planted too early. Even as late as May 14, there is still a 10 percent chance we could receive a frost in our area. And we have had some very cool nights lately.

But even if frost protection is provided, there is really nothing to be gained by planting tender transplants too early, because if it’s not warm enough, plants will not grow. It is best to wait 1 to 2 weeks after the last frost date, until after Memorial Day or early June, to plant tender transplants out in the garden.

There are many flowers, like marigolds and zinnias that are warm season transplants which are also sensitive to frost, and one should wait to plant these as well. Make certain to harden-off transplants before planting out, by gradually exposing them to outside environment, so they are acclimated enough to tolerate the stresses. Also wait until after Memorial Day to sow seeds of pumpkin, squash, melon, cucumber and other warm season plants that require warm soils to germinate.

With rainfall recently received in our area, be sure to delay any garden planting due to wet soil conditions. Make certain that the soil has dried out enough before planting, as working wet soils can harm the soil structure, causing clods and compaction – think mud pies.

To determine whether the soil is ready to be worked, squeeze a handful. If the soil keeps its shape, forms a ball that stays together in your hand, the soil is too wet to be worked. If the soil ball crumbles and falls apart in your hand, then you may work the soil and plant your garden.

Did you know? The term “friable” refers to a soil texture that is crumbly, loose and perfect for planting.

For further information on setting out transplants or other gardening questions, contact Yvonne McCormick at yvonne@iastate.edu