What to do in your Iowa garden this month
IOWA CITY– Wow. What a spring– or is it summer? Either way, gardens are going gangbusters and it’s a challenge to keep up.
The last average frost date is almost here. It’s May 10 for southern Iowa and May 15 for northern Iowa, though this year, you’re probably safe sneaking things in a few days early. So tuck in those tomato plants, peppers, basil, marigolds, impatiens and others after this date.
Plant gladiolus corms, canna rhizomes, and tuberous begonia tubers now the soil is adequately warm.
You can continue to divide perennials that bloom in the summer or fall now, as needed or desired. Hold off on dividing those that bloom in late spring until either after they bloom or this fall.
Continue to plant trees, shrubs and roses. However, avoid planting bare-root roses and other bare-root plants after the middle of May.
Continue to plant perennial edibles that like cool weather, such as rhubarb, strawberries, raspberries, and asparagus.
Normally, you’d have to wait to plant the seeds of corn, squash, cucumbers, and beans. They like warm soil. If you want to be safe, plant these the last week of May in southern Iowa, the first week of June in northern. But otherwise, this year, you should be fine planting them a couple of weeks early.
If you choose to use a pre-emergent weed killer, such as Preen, in your beds and borders, now it the time to apply it. Organic versions are also available. Look for products that also fertilize.
You can mulch now. I like to wait until the soil warms up– which is usually about the time the daffodils are all fading.
Don’t remove the browning foliage of tulips and daffodils until it pulls away easily. The plants need it to rejuvenate for next year. But you can (and should) trim off spent flowers from daffodils, tulips, and other-spring blooming bulbs. Deadheading also helps the plant rejuvenate for next year.
Veronica Lorson Fowler lives in Ames and is the author of several garden books, including “Gardening in Iowa” published by the University of Iowa Press. Subscribe to her free electronic Iowa gardening newsletter or ask her your garden questions at www.theiowagardener.com.
Photo credit and caption:
Peonies, roses, and other late May to early June favorites are already blooming now.