May brings us an abundance of beautiful flowers and fresh, vigorous growth—the garden is really starting to hit its stride!
Our early Spring work is finally paying off, and plants are performing well without the need for much supplemental water or pest and disease control. Now is the time to fill in any gaps in the landscape, get your outdoor areas set up for Summer, and bask in the beauty of this shoulder season.
May To Do List in the Garden
Update your curb appeal! Refresh landscape plantings and patio pots with showy summer color.
Use annuals in landscape beds to fill space between young shrubs and perennials, compete with weeds, and keep the yard in full bloom all summer long!
- Some favorite annuals for sun include: Bacopa, Cosmos, Geraniums, Marigolds, Million Bells, Petunias, Snapdragons, Sweet Potato Vine, Verbena, Zinnias
- Check out these annuals for shade: Begonias, Coleus, Impatiens, Tender Fuchsias
Plant perennials for color that returns year after year. Plant in Spring while the soil is still wet to get them established before the heat of summer.
- Long-lasting or showy blooms: Peony, Lupine, Foxglove, Delphinium, Geum, Hardy Fuchsia, Hardy Geranium, Lilies
- Stunning foliage for drama and texture: Brunnera, Heuchera, Hostas, Ferns, Ornamental Grasses
Plant shrubs to complement perennials and get them established during the cooler, wetter season.
- Blooming shrubs: Azaleas & Rhododendrons, Hydrangeas, Lilacs, Roses
- Shrubs with colorful foliage: Barberry, Euonymus, Mexican Orange
Planting & Maintenance
Remove spent flowers before seeds form on spring flowering bulbs like tulips and daffodils. Wait for foliage to yellow before cutting to the ground – the nutrition in the green leaves feeds the bulbs so that the display will be bigger and better next year!
Deadhead Rhododendrons and Azaleas just after bloom; remove flower clusters—snap at natural break point just above where new leaves emerge. May is the best time to prune Rhodies, Azaleas, and Camellias for shape; pruning after bloom ensures an unaffected flower set for next year.
Hard prune durable, spring flowering shrubs like Lilacs, Forsythia, Flowering Quince, and Twig Dogwood after bloom to remove dead wood, control size, and maintain shape. Regular thinning of the largest, woodiest canes should also be done to encourage fresh growth and reduce disease potential.
Improve soil health and water retention with mulch. See our blog for The Whys & Hows of Mulch!
Monitor and treat Rhododendrons and Azaleas for lace bugs and root weevil damage. Be on the lookout for black spot on Roses and Fruit Trees.
Fertilize trees and shrubs if they have not yet been fed:
- G&B All Purpose Fertilizer for trees, shrubs, and perennials that are prized for their foliage.
- G&B Rhododendron, Azalea & Camellia Fertilizer for shrubs listed, plus conifers, maples, and blueberries that prefer acidic soil.
- G&B Citrus & Fruit Tree Fertilizer for citrus and other heavy feeding, acid-loving plants like gardenias, and for foliage/flower production and a bountiful harvest with fruit trees and berries.
- G&B Bud & Bloom Fertilizer to promote ample, luscious blooms on summer-flowering shrubs, perennials, and annuals.
- G&B Tomato, Vegetable & Herb Fertilizer for all edibles including perennial vegetables and herbs.
- Fertilize hydrangeas with G&B Bud & Bloom Fertlizer to encourage vigorous growth and lush blooms. To make/keep flowers pink, add horticultural lime to the soil, and for blue flowers, add aluminum sulfate or Hydrangea Blueing Formula.
Plant warm-season edibles outdoors once nighttime temperatures average around 50ºF and soil and air temperatures warm up to 60ºF reliably.
- Tender and tropical herbs: Basil, Cilantro, Dill, Tender Sages, Lemongrass, Lemon Verbena
- Vegetables to start from seed: Beets, Melons and Cucumbers (end of month; watch soil temps), Carrots, Corn, Leeks, Peas, Potatoes, Radishes, Beans, Lettuce, Parsley
- Vegetables to plant as starts: Broccoli, Cabbage, Cauliflower, Celery, Eggplant (end of month), Lettuce, Onion, Parsley, Peppers (end of month), Pumpkin, Squash, Tomato, Melons and Cucumbers (end of month; watch soil temps)
- Add Horticultural Lime to provide calcium to soil for a productive harvest and help prevent blossom end rot. Apply to garden soil for Cucumbers, Eggplant, Melons, Peppers, Pumpkins, Tomatoes, Spinach, Summer Squash, and Winter Squash.
Monitor fruit trees for signs of pests; place traps for coddling moths in apple trees and plan for control if moths are found.
May Lawn Care
Fertilize lawn with G&B Lawn Fertilizer.
Hand pull or treat broad-leafed weeds with Bonide Weed Beater Ultra before reseeding bare patches with fresh lawn seed.
Use Bonide MoleMax for gopher and mole issues.
Prepare and prime your irrigation system for summer watering.
Indoor Gardening in May
Establish a regular care routine of watering, fertilizing, rotating plants, and inspecting for pests.
Take houseplants outside on a mild day for some natural light and even a shower to clean the leaves. Be cautious of burning foliage with intense sunlight and avoid cold temperatures; bring tender plants back inside at night.
Repot houseplants that have not yet been potted up and need more space.
What to Do for Fun in May
Celebrate Mother’s Day with a colorful hanging basket or gift card, or check out our guide to unique gift ideas for Mother’s Day!
Count and photograph your pots so that you have an easy reference point for plant quantities and needs when you come to the Garden Center.
Deck out your patio with a new outdoor cushion or rug to make the space feel fresh and new.
Get outside! The best way to know what to do in your garden is to spend quality time in it!
View our garden tips and checklist for June in the Garden. Or go back and see our garden tips and checklist for April in the Garden.