The June Garden Checklist: Tasks to Tackle Now for a Healthier Summer Garden

As temperatures rise and plants firmly take root, June is one of the busiest and most rewarding months in the garden.

Seasonal garden maintenance in early summer sets the foundation for productivity during peak heat and harvest months. PIKSEL/Getty Images

June 21 is the official start of summer this year, but you’ll be able to find new discoveries in the garden throughout the entire month. Many regions of North America are seeing lush greenery and colorful blooms, sprouting summer seeds, hot-weather transplants ready to be planted, and some veggies and greens that are already giving generous harvests. It’s a gardener’s dream season.

However, at the same time, the rising temperatures mean increased watering, weeds having growth spurts, and bugs beginning to arrive in force. Although the coming weeks can put even the savviest horticultural skills to the test, doing these simple chores now will give the garden, and the gardener, a distinct advantage.

Mulch, Mulch, Mulch

Apply long-lasting, weed-suppressing, soil-enriching, moisture-conserving organic wood chips, hardwood mulch, or pine needles around flowering plants, ornamentals, shrubs, and trees. The goal is a two- to three-inch layer, with a two- to three-inch gap around the plant stem or tree trunk to avoid creating an area conducive to fungus, bacteria, and rot.

Four inches of mulch will offer additional weed suppression for pathways and large spaces between beds, where rain permeability is less of a consideration.

The best mulches for vegetable gardens are two to three inches of homemade compost, straw, or shredded leaves. Those will break down fast to feed the hungry vegetable plants.

Organic mulch helps regulate soil temperature, reduce water evaporation, and suppress weed germination. New Africa/Shutterstock

Fertilizer Facts

For many regions, June is the last chance to fertilize shrubs and trees, since fertilizing in July can cause vulnerable new growth that may not have sufficient time to harden off before the first frosts arrive.

It’s also a good time to fertilize warm-season grasses, such as Zoysia and Bermuda, for lush summer growth. Choose a slow-release formula to avoid burning the lawn. Wait for fall to fertilize cool-season grasses such as Kentucky Bluegrass and Perennial Ryegrass.

To maximize flower production, fertilize with a balanced or plant-specific liquid fertilizer every two weeks, or opt for slow-release pellets.

Garden goodies such as tomatoes, squash, corn, cucumbers, and peppers will all benefit from a general veggie or plant type-specific slow-release fertilizer to bolster summer growth. Keep it four to six inches from the plant stems. Wait seven to 14 days before fertilizing transplants.

Fertilizers provide the nutrients vegetable plants need as they start producing. mgstudyo/Getty Images

The Supportive Gardener

Tall flowering perennials and many veggies (tomatoes, pole beans, peas, and peppers) that grow more than two feet tall on a thin stem will benefit from proper staking. Typical options include bamboo, metal, and wood stakes, plant rings, hoops, tomato cages, and trellises. Now’s the time to install them securely—for example, push stakes at least six inches into the ground—before the plants grow any taller.

Staking plants before they become top-heavy helps prevent the stems from breaking. Roman Bulatov/Getty Images

Beneficial Beauty

There’s still time to plant seeds for marigolds, calendula, poppies, impatiens, sunflowers, nasturtiums, zinnias, echinacea, cosmos, and other summer bloomers that attract pollinators and other beneficial insects. Now is also the time to plant dahlias, gladiolus, canna lilies, caladiums, and other warm-weather bulbs.

Direct Sown Ease

Cucumbers, melons, corn, and carrots all prefer to be direct sown, rather than transplanted. Others on the “it’s not too late to plant seeds directly into the garden” list include beans (bush and vine), zucchini, okra, and winter squash.

Direct seeding allows heat-loving crops such as beans, corn, and squash to establish strong root systems without transplant shock. Agatha Koroglu/Shutterstock

Tactical Trims

Prune azaleas, forsythia, and rhododendrons as soon as they’ve finished blooming. Wait too long and there’s a risk of accidentally removing next year’s buds.

Lilacs should be deadheaded (remove spent blooms), and you should remove some older woody stems to encourage new growth.

Give lavender a light trim, but avoid cutting any old woody stems, as they can have a hard time recovering.

Climbing roses should be deadheaded and given a light shaping. For roses that bloom only once per year, such as the Cherokee rose, wait until they’ve finished flowering. Hold off on the wisteria, too, which typically finishes flowering in mid-to-late summer.

Timely pruning helps many shrubs conserve energy for next year's bud development. Oliver Rossi/Getty Images

Garden Guardian

Put on some zen music and brew an herbal iced tea, then get out there before or after the high heat of the day to inspect the garden—particularly veggies—daily. Spray aphids with a robust blast of water before they become a full-blown infestation. Remove beetles by hand and drop them in soapy water, or spray them—as well as whiteflies and stink bugs—with an insecticidal soap.

Remove tomato hornworms manually (yes, it’s gross!) and reduce caterpillar population on broccoli, cabbage, and other brassicas by spraying Bacillus thuringiensis. Inspect juniper, arborvitae, and other evergreens for bagworms, and spray while they’re small with Bacillus thuringiensis, as they may be too big in July and they can decimate plants quickly. Simple beer traps work well for slugs.

It’s also time to ramp up the weeding. Pull them daily; otherwise, they’ll steal nutrients from, and eventually choke out, prized plants.

_________________________

Garden Whisperer

Trim and harvest herbs often to keep the plants youthful and compact, and pick tomatoes, peppers, and cucumbers regularly to help increase their production.

Aqua Oasis

Lawns, trees, shrubs, and ornamental beds should get one to 1 1/2 inches of water per week and up to two inches in August for warmer regions. Check the landscape sprinkler system for leaks and broken parts. No system? Consider installing one.

Vital Veggies

The rule of thumb is one inch of water per week, deeply watered more than three times per week, but in reality, many veggies need more as temperatures rise—particularly those in container gardens. Get a rain gauge and moisture meter, and consider a DIY drip irrigation system.

Wise Watering

The best time to water is early—5 a.m. to 9 a.m.—so it can soak in. The second choice is in the late afternoon or early evening to reduce the risk of wet feet and leaves overnight. Ideally, always water at the base of plants, not from overhead, which can lead to fungal and bacterial problems on the leaves.