What to do in the Garden in May and June


  • Mow lawn at least three inches high. This encourages deeper, healthier root growth. Leave grass clippings on the lawn to provide nitrogen.
  • The first application of lawn fertilizer can be put down around Memorial Day. If fertilizer was applied in fall a spring application is not necessary. A top dressing of compost is an excellent and natural fertilizer.
  • For optimal pre-emergence crabgrass control, do not apply until soil is close to 60 degrees. Crabgrass doesn’t germinate until the soil temperature 2 inches deep is between 60 & 64 degrees. Applying when the ground is too cold is a waste of money and chemicals.


Avoid overcrowding when planting. Good air circulation helps prevent fungal disease.

Check the Cornell Recommended Vegetable list for suggested and disease resistant varieties.

Plant your brassicas now: broccoli, cauliflower, Brussels sprouts, summer cabbage

Plant new batches of bush beans every few weeks to replace those that become exhausted.

Leeks may be moved to their final growing place in the garden.

Plant your tomatoes when the ground is warm. Don’t plant too early as this encourages blossom end rot. If you grew them from seed be sure to harden off your plants first.

Some salad greens, radishes, and spring onions may be ready for harvesting.

Begin staking tomato plants. Pinch out sucker growth.

Annuals & Perennials:

Buying plants:

Look for compact, healthy plants in bud. If you buy perennials in full bloom there won’t be many flowers left for the rest of the season. Annuals in full bloom will need a lot of energy to keep the flowers going rather than setting new roots. You’ll have healthier plants in the long run.

Check for signs of insects or disease on both sides of the leaves.

Check plant tags to make sure your growing conditions meet the plant’s needs and that the final height and width is appropriate for your space.

A weak or diseased plant is no bargain.

Buy yourself at least one new plant!

Leave bulb foliage intact until it yellows and wilts. The foliage is required to give the bulb energy for blooming next year.

Watch for white trails on columbine leaves caused by leaf miner. Remove and destroy infested leaves throughout the season.

Pinch back perennials like phlox, bee balm, and Autumn Joy sedum to control height or delay flowering.

Control the height of Fall blooming perennials like aster and solidago by cutting back by ½ to 1/3 when the foliage is 1 to 2 feet tall.

Cut back spring flowering perennials such as pulmonary and perennial geraniums after they bloom to encourage the growth of new fresh foliage.

Cut back some perennials such as sedums and echinacea before you see flower formation to delay blooming and to produce shorter more compact plants.

Deadhead perennials regularly. Many perennials will rebloom if deadheaded promptly.

Plant annuals in the bare spots in your perennial gardens.

General Gardening:

Start slug control and check for four lined plant bug.

Scout out and remove tent caterpillar nests.

If deer are a problem, begin using deer repellants.

Prune spring flowering trees and shrubs as they complete their bloom.

Keep up with weeding. It’s much easier to remove a weed when it’s small. If you don’t have the time to weed at least remove the seed heads before it can drop seeds.

Keep newly planted plants well watered.

Renew mulch as necessary.

Turn your compost.

Thin out your fruit trees if necessary to ensure fruit of a reasonable size. Also make sure fruit trees receive adequate water.

Give your houseplants a treat by placing them outdoors. Do this gradually so as not to scorch them.

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