“All things seem possible in May,” someone said, and that’s a good way to approach May gardening chores. You still have time to give your flowering shrubs a boost by dosing evergreen plants—rhododendron, azaleas, camellias, etc. with acid fertilizer. Give roses, trees, and deciduous shrubs a boost of all-purpose (10-10-10) fertilizer.
In late May, start planting gladioli, and plant at two-week intervals. You’ll be “glad” you did. Gladiolus bulbs will return year after year, and some will spread.
Place mulch around new trees and shrubs to retain moisture and prevent damage from lawn mowers.
Prune back forsythia, weigelia, and spiraea after they finish blooming, cutting about one-third of the oldest canes to ground level. Also cut one-third of the remaining branches back by one-third.
When azalea and rhododendron flowers wilt, remove the seed heads to force energy into foliage.
Keep conifers under control by pinching back new growth.
Prune lilacs after they bloom and fertilize with 10-10-10.
In May, plant summer flowering bulbs and tubers such as dahlias, tuberous begonias, lilies, and cannas. You can plant up to the first of July to extend the period of bloom.
Thin out old daffodil plantings after they finish blooming. Dig the bulbs out carefully, treating them as plants and protecting the roots. Water thoroughly after replanting them in a new location.
In the Midwest and North, wait until mid May to plant tomatoes, squash, cucumber, pumpkins, and peppers. Plant carrots, lettuce, potatoes, corn, beans, peas, and most other vegetables any time in May.
To protect newly transplanted vegetable plants, place 2-inch-wide by 8-inch-long cardboard collars around them, pushing the collars one inch into the soil. These will serve as effective barriers to cutworms.
May your efforts this month in the garden pay off with a bountiful harvest.