Northern Region
In the northern tier of states, such as Minnesota, Michigan, and Maine, spring weather starts to warm up to the point where you don't need to worry about frosts and cold snaps anymore. Garden center shopping sprees are ongoing, and it’s time to get digging.
Vegetable & Herb Garden
Last spring frost dates in late April and throughout May mean it’s time to harden off seedlings and start transplanting. Most veggies can be planted this month. Watch the long-range weather forecast and look for a pattern of warming weather. Average frost dates are just that, and they vary from year to year.
Direct seed sweet corn, beans, squashes, pumpkins, cucumbers, and others after your last frost date.
Succession plant more lettuce, spinach, kale, and peas.
Harden off seedlings like tomatoes, peppers, and eggplants. Wait about 10 days after your last frost to transplant them into the garden.
Put out your rain gauge and start keeping track of weekly rainfall.
Flower Beds, Perennials, and Ornamentals
The tulips are finishing for most in this region, but peonies, serviceberry, and lilacs are in bloom. As you're enjoying the flower show, it's a good time to think about replacing any plants that didn't make it through the winter while conditions are still ideal for new roots to establish themselves.
Plant annuals like sunflowers, zinnias, and cosmos as soon as night temperatures stay above 50°F.
Summer flowering bulbs and tubers like gladiolas and dahlias can go in the ground this month.
Plant bareroot and containerized nursery stock, then keep them well watered.
Allow your tulips and other spring bulbs time to recharge. Leave the foliage even after the blooms are finished.
To-Do Checklist
Mulch planting beds well to keep down summer weeds.
Take stock of what, if anything, you have blooming for the pollinators this month. Plan what to else you could plant to help them out next year.
Cut some lilac branches for a beautiful and fragrant bouquet.
Middle States
May feels like the start of summer in the middle regions, with green grass, fully leafed out trees, and significant progress in the garden. Cabbage, broccoli, lettuce, and other cool-season crops are large and lush, and it’s a great month to be in the garden.
Vegetable & Herb Garden
Now that the last frosts have passed, it’s time to transplant tomatoes, peppers, and any other warm-season crops, if you haven’t already. Get them in the ground about 10 days after your last frost, or when the weather has warmed enough that the furnace doesn’t run much anymore.
Harvest asparagus and rhubarb as it comes in season.
Trim off garlic scapes for use in soups and stir-fry.
Thin seedlings of lettuce, beets, corn, and other direct-seeded vegetables as they begin to crowd each other.
Watch for aphids, spider mites, and tomato hornworms at the end of the month.
Flower Beds, Perennials, and Ornamentals
Early May is still a fine time to get annual flowers in the ground or into pots. And most perennial plants are hitting their stride with fresh growth.
Continue fertilizing roses.
Plant any remaining gladiolas, dahlias, or other summer-flowering bulbs and tubers you may have.
Deadhead peonies, but leave their foliage intact.
To-Do Checklist
Keep up with weeding. May for this region is the start of the annual weed flush.
Increase watering frequency as the weather warms up. Check soil moisture every couple of days.
Turn the compost pile, and keep it properly moistened. A dry pile won’t decompose very quickly.
Prune spring-flowering shrubs after they’ve finished blooming for the year.
Southern Region
In Texas, Georgia, Florida, and other southern states, May means green gardens, harvesting produce, blooming flowers, and the beginning of the truly hot weather.
Vegetable & Herb Garden
From planting in early May to harvesting as the month progresses, May is a busy vegetable garden time in Southern states. The first zucchini, fall-planted onions, and even a few tomatoes might be ready depending on your climate.
Watch for early blight on your tomatoes.
Scout for common pests like aphids (wash them off with the hose), spider mites, hornworms, and more. Catching them early is the key to effective management.
Plant okra, Southern peas, eggplant, watermelons, and other heat-loving crops.
Keep winter squash and pumpkin vines under control, training or pruning them.
Flower Beds, Perennials, and Ornamentals
Deadheading, weeding, and enjoying bouquets are the game this month. As the heat sets in, gardening shifts to maintenance instead of planting.
Diligently irrigate newly planted perennials. Herbaceous perennials need an inch of water per week, more in hot, dry weather. Newly planted shrubs and trees need weekly (more often for the first few weeks) deep watering unless the weather has brought sufficient rain.
Watch in your groundcover areas for weeds flowering and setting seed. Pluck them out to reduce problems later.
Deadhead spent flowers to encourage more blooms.
To-Do Checklist
Prune suckers from tomato plants and keep up with trellising and tying them up.
Finish harvesting peas and other cool-season crops at the beginning of the month. Replant those areas with warm-season crops or cover crops.
