May in Iowa will often change from year to year, but we've made a list of gardening tasks that are usually best completed in May. Here is what you should be working on in the garden.
Spring Clean Up
√ If anything has been missed during your April clean-up, make sure to get it now. Make sure all perennials are cut back to avoid new growth from growing through the dead foliage. This is especially important for ornamental grasses
√ Prune out any dead branches on trees and shrubs. It may be too early to tell at the beginning of the month, so continue to watch for new growth on branches. Some plants do take longer to come out of dormancy, like Rose of Sharon and roses. Only trim out branches that you are certain are dead (snap off easily and show no life inside of bark).
√ If you have any spring flowering shrubs that need to be pruned, make sure to trim those right after blooming. This will likely not be until the end of the month, so mark it on your calendar. Pruning spring flowering shrubs right after blooming will help ensure that you do not cut off next year's blooms.
Planting & Prepping
√ If you have not been able to get into your garden due to cold, wet weather, this month is a fine time to start. Start amending your garden soil with compost or fertilizer. Add compost to lighten clay soil. Only work the ground once it dry.
√Plant trees, shrubs, and perennials.
√Plant cool season veggies, onion sets, and potatoes, as well as direct sow peas and beans now. Plant tomatoes, peppers, and other warm season veggies in the middle of the month.
√If you skipped cleaning out your containers last fall, now is the time to do so before you add new plants. Be sure to remove all potting mix and replace with fresh potting mix. This will help your container plants thrive and get the nutrients they need to look amazing this spring into fall. If you had any disease issues in your containers last year, be sure to disinfect with bleach.
√Start planting summer containers. If starting the first of May, check the extended forecast and plan to protect soft tissue plants like coleus, impatiens, and begonias if the temperatures should dip close to freezing. Nighttime temperatures should be around 40 degrees for most summer annuals and 50 degrees for tropicals.
√Put down a pre-emergent (like Preen) on beds to help combat weeds this spring (if you haven't already). Make sure to avoid any area you will be planting seeds.
√Watch for animals chomping on your plants. Use a repellent early to deter animals from making your yard the neighborhood buffet.
√Put down Sluggo or diatomaceous earth in your hosta beds to prevent slugs from munching on new leaves. Prevention now will help the plant look its best. If caught too late, many of the leaves will have visible damage throughout the growing season. Go one step further and mulch with pine needles to keep slugs away.
√ If you didn't get your houseplants repotted in March, there is still time to do so. Late in the month, you can move struggling houseplants outdoors for a little vacation to help with growth and lack of sunlight during the winter months.
√ Continue fertilizing houseplants that are not in bloom.