You may be able to get another crop of quick-maturing, cool-season vegetables (such as radish, lettuce, or spinach) if you sow the seeds early this month and live in cooler parts of the Northeast.
Here's a hint: If your summers get hot early, plant lettuce, spinach, and other greens in the shade. They'll stay cooler -- and that can keep them going longer.
If you didn't harvest all of your cool-season crops and they sent up a flowering stem (called bolting), toss them in your compost pile. Unfortunately, once they bolt they become too bitter to eat.
Stop harvesting your rhubarb and asparagus; they need to produce a healthy crop of leaves for the rest of the summer to gather energy and give you abundant harvests next year.
Once you've passed your average last frost date, it should be safe to plant your warm-weather vegetables, including tomatoes, peppers, eggplants, corn, squash, and pumpkins.
During dry spells, water your vegetable garden deeply, but infrequently. That way your plants grow deeper root systems so they can weather, dry periods easily.
Reduce your watering bill and help protect your vegetables from fungal diseases by using a soaker hose.
Once the soil has warmed up, plant showy summer-flowering bulbs for a great warm-weather display. Varieties such dahlias flower all summer long -- and are great for bouquets.
Others, such as cannas, add visual bang to your garden thanks to their brilliant foliage. Purchase bulbs from local garden center or nursery and plant a variety so you can keep your garden looking great.
Wait to remove the foliage on your tulips, daffodils, hyacinths, and spring-flowering bulbs until it's gone fully yellow and pulls easily out of the ground. If there's still some resistance when you try to pull it out of your garden, the bulbs are still absorbing sunlight for next year's floral display.
It's a good time to map out your bulb garden if you haven't already. Refer back to your diagram this autumn when you plant more spring-flowering bulbs -- that way you know exactly where your existing bulbs are and which varieties are where.
Walk through your yard at least once a week and cut off dead, faded flowers. This process is called deadheading and it encourages many varieties to keep blooming. Deadheading prevents your plants from going to seed (so you won't have a crop of seedlings to pull) and can protect your plants from some fungal diseases.
Fungal diseases thrive in cool, moist conditions. Some plant varieties are especially susceptible to certain diseases; treat roses, phlox, bee balm, lilacs, crabapples, or other varieties that always seem to get powdery mildew or leaf spot diseases with a fungicide during bouts of wet weather. You can usually prevent the diseases from taking hold.
If certain varieties frequently suffer from the same diseases, divide or prune them so air can flow freely between the branches and leaves. Many fungal diseases love still air.
Wet conditions also usually bring the slugs out in force. If you see chewed holes in your plant leaves, use a slug bait to get the pests under control. There are traditional and organic types available -- look for them online or at your local garden center.
Also: Encourage critters such as snakes and toads as both eat slugs.
Watch for insect pests such as aphids, cabbage loopers, and Japanese beetles. If the populations are small, you may be able to keep them under control by hosing them off plants with a strong stream of water (for small insects) or hand-picking them from the plants (for larger bugs).
With most perennials, it's just fine to divide them any time from spring to fall. But it's easiest on the plant if you split it in cool, moist conditions. So dig out and divide clumps of your perennials to share with friends or to fill in gaps or holes in your garden.
Make more of many of your favorite shrubs! It's an ideal time to take cuttings of trees and shrubs, such as chokeberry, butterfly bush, spiraea, serviceberry, hydrangea, dogwood, and magnolia.
Prune lilacs and other spring-flowering shrubs once they've finished flowering. If you prune them after this month, you could be cutting off next year's flowers.
Weeds are so much easier to pull when they're small -- so spend time in your garden going after them now. If you remove the weeds before they go to seed, you'll have to deal with fewer weeds next year.
Keep mowing your lawn as it grows. One way to make your lawn extra lush and healthy lawn is to let it grow about 2-1/2 inches tall before mowing it. (And when you do mow, don't remove more than a third of the grass's total height.) Longer grass blades mean deeper roots, so your lawn holds up better to foot traffic and hot, dry weather. Plus, taller grass shades out many low-growing weeds.
If you have a cool-season lawn and didn't fertilize in May, do it early this month. But don't wait too long -- it's best to let your grass slow down and get ready for summer.
Aerate cool-season lawns when your grass is actively growing. Rent an aerator if your ground seems hard and the grass isn't growing much. The looser your ground is, the better job your grass will do at crowding out weeds.