Long Island Horticultural Society

What's Going on in the Garden

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May To Do List

  • To prevent them from wasting energy on producing seed, deadhead your spring bulbs after they are done blooming.

  • Fertilize your plants.

  • Deadhead pansies and primroses after they have finished flowering.

  • Stay ahead of your weeding chores: Once temperatures soar, weeds and/or invasive plants can quickly get ahead of you.

  • Turn over your compost pile, or, if it has already broken down, use that compost in the garden and start a new pile.

  • Begin hardening-off frost tender plants now including vegetables, herbs, perennial and annual flowers that have been started indoors.


Be on high alert for insect pests and diseases. These include, but are not limited to, aphids, asparagus beetles, cabbage worms, cutworms, scale, snails, slugs, leaf spot, mildew, and rust.

Squash vine borer adults are 1 inch long, orange and green day-flying moths that are emerging from the soil now. They lay brown, button-shaped, 1/16 inch eggs at the base of the vines of summer and winter squashes. Examine stems daily and remove eggs by hand to prevent burrowing of larvae as they hatch. Wrap lower 6 –12 inches of stem with aluminum foil or floating row cover to prevent egg laying.

Newly transplanted vegetable plants should be protected from cutworms with collars. Cut strips of cardboard two inches wide by eight inches long, staple them into circles and place them around the plants. Press the collar about one inch into the soil. These collars will fence out the cutworms and protect the stems of the vegetable plants.

Continue harvesting cool-season crops like asparagus, peas, and leafy crops. Keep an eye out for pest such as groundhogs and rabbits so that they do not get to your harvest before you do.

  • Plant asparagus if you do not already have some. (Late May into June)

  • Plant members of the nightshade family.(Tomatoes, Potatoes, Eggplant)

  • By the end of this month, it should be safe to plant almost everything outdoors -tender annual flowers like impatiens as well as tomatoes, peppers, and eggplants. Houseplants, too, can be moved to a shady spot in the yard for their summer vacations.

  • Finish sowing seed for annuals.