A May gardening to do list

The last average frost date is almost here.

It's May 10 for southern Iowa and May 15 for northern Iowa. That means you can plant just about anything outdoors now and not worry about it getting damaged by cold.

So tuck in those tomato plants, peppers, basil, marigolds, impatients and others after that date.

Here is your May gardening to do list:

' Plant gladiolus corms, canna rhizomes and tuberous begonia tubers now that the soil is adequately warm.

' Finish planting lettuce and spinach from seed.

' 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.

' Finish up pruning trees, shrubs, evergreens and roses now as desired.

' Continue to plant trees, shrubs and roses. However, avoid planting bare-root roses and other bare-root plants until after the middle of May.

' Continue to plant perennial edibles that like cool weather, such as rhubarb, strawberries, raspberries and asparagus.

' If you choose to use lawn chemicals, do your spring application of a fertilizer and a pre-emergent herbicide now, or use a combination product. An organic alternative for a pre-emergent is corn meal gluten.

' Wait to plant the seeds of corn, squash, cucumbers and beans. They like warm soil. Plant these the last week of May in southern Iowa, the first week of June in northern.

' 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 also are 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.

' If you like, erect supports for peonies now while they're small. Once in flower, they tend to flop badly, especially after a rain. You can buy grow-through supports, or just use smaller-type tomato supports.

' Don't remove the browning foliage of tulips and daffodils until it pulls away easily. The plants need it to rejuvenate for next year. However, if your tulips and hyacinths were spindly and weak this year, do pull them out. Unlike other spring-blooming bulbs, tulips and hyacinths last only two to three years before they peter out.

l Veronica Lorson Fowler is co-publisher of The Iowa Gardener website at www.theiowagardener.com.