May 15th is the last frost date for Zone 3. After the first day of Spring, many of us are chomping at the bit to get out in the garden and begin spring planting. A little caution is called for since the weather can be unpredictable and a late freeze or snowstorm can undo a lot of hard work. Prepare to protect seedlings in the garden from frost by preparing cages and stakes that you can cover with cloth on cold nights. (Find your zone using the map on the right; click to enlarge.)
In the last week of the month, remove winter covering from tender roses, perennials, and strawberries.
Cut back the dead top growth of perennials and perennial grasses, leaving about 3 or 4 inches of stems.
Now is the time to divide mature perennials that are bare in the center, no longer bloom well, or are taking up too much territory, as well as those you wish to propagate. Divide when the new growth is 4-6 inches tall. Do not divide the very early spring bloomers such as bleeding heart until after blooming or in fall.
Flush planting beds near the street with plenty of water to dilute the road salt that has accumulated in the soil.
Fertilize spring blooming bulbs in late April or early May.
Begin to remove a little of the mulch in the perennial flower garden. Don’t remove it all at once since this will expose the emerging foliage and flower buds to spring freeze damage. You can use a broom rake to pull away a little each week.
Sort through stored tubers, roots and bulbs for dahlias, cannas, glads and begonias. Dispose of anything that has shriveled or decayed. Start looking for new summer flowering bulbs you want to add to the garden for summer color.
Dig up and enjoy parsnips and carrots still left in the garden from last fall.
Sprout seed potatoes by moving them from cold storage into room temperature.
When the soil has thawed and dried and begins to warm up, usually around middle of the month, you can remove winter mulch. Work compost or leaf mold into the top layer of the soil.
Add new garden beds now while you have time.
Dig compost into beds as soon as you can work the soil. Also put in any other amendments such as lime or grit. Lime needs time to break down into a form usable to the plants.
If weather allows, plant onion sets, lettuce, spinach, peas, sweet peas, carrots, and parsnips in the garden. Indoors, start seeds of squash, melons, and peppers.
Plant tomato seeds indoors using a good quality potting soil. Moisten the potting mixture before planting, and set the seeds directly on top; then cover with 1/4- inch of vermiculite. This sterile material will help prevent damping-off disease that often causes the collapse of the stems. Cover the container with clear plastic and set it in a warm spot. Remove the plastic when all the seeds have germinated and sent up leaves. Place the seedlings under lights for 12-14 hours a day until they are big enough to go outside.
Sow cold-crop vegetables like leafy greens and most root vegetables directly into the garden once soil temperatures warm, even if there is still a risk of frost. Many root vegetables don’t like transplanting, so planting them directly into the ground is the only option.
High winds, heavy snow and freezing rain can damage our gardens and yards in the winter, so spring is the time to inspect for damage, prune back or remove broken stems and branches, clean up any debris and remove any plants that just didn’t survive.
Plant container grown shrubs and trees by end of the month, unless of course, it is still snowing.
Every few years, potted trees and shrubs should be re-potted and root pruned. Top dress each year before growth begins.
The cardinal rule is to prune shrubs after they bloom, but for late-blooming clematis and hydrangeas, various shrubs and fruit-bearing woody plants, early spring is the time to prune them into shape. Don’t cut them back drastically, though, or they won’t flower.
Now is a good time to fluff the lawn with a broom rake. As lawns mat down over the winter, a lack of air circulation around the grass plants can lead to mold diseases. The bright sunshine has a powerful sterilizing effect, and fluffing the grass will add air and help prevent fungal lawn diseases.
Avoid the urge to apply fast-release lawn food to your lawn. Pushing the grass to be the greenest will predispose your lawn to leaf spot diseases. Additionally, the lawn will need to be watered earlier, mowed sooner and more often.
Raised bed image: Shutterstock/Alison Hanson