Stephen Albert
Summer arrives toward the end of this month. Now is the time–before hot weather arrives–to finish your spring garden chores.
After weeding beds and borders, sprinkle slow-release organic fertilizer around each plant then add an aged compost mulch across beds. Aged compost will work itself into the soil through the summer improving both moisture retention and drainage. It will also feed the soil and your plants. Water plants slow and deeply; roots will follow moisture deep into the soil and plants will easily stand up to summer heat. Faded blooms should be removed from early-blooming perennials and shrubs.
Shade newly set out plants until their roots get established. If you are setting out plants just purchased at the garden center or raised yourself under glass be sure to acclimatize them to the garden by setting them out in a shaded place for a few days before planting. Keep the garden free of weeds; weeds compete with ornamentals for nutrients and water. Keep an eye out for insects and diseases. Attend to small problems immediately; that way they won’t turn into big problems.
In Zones 7 to 3, keep an eye on the weather forecasts this month. Late spring can be deceptive. It often seems as though summer has already arrived, yet in many northern and mountainous regions, severe frosts can still happen. Take the local climate into account before planting any frost-tender plants outdoors. A good guide is to watch when summer bedding is put out in local parks. These gardeners will have amassed generations of local knowledge of your area, which is by far the best guide.
Here is a zone-by-zone to-do list for June. You’ll find planting and garden care tips for trees and shrubs, perennials, annuals, bulbs, the lawn, and container gardens for your region.
Use the USDA Hardiness Zone Map below to check your zone if you are unsure.
If you are unsure when the last frost in spring happens where you live–and when the first frost in autumn comes. Go to this post: Average Last and First Frost Dates for Cities, States, and Countries. The months between the last frost in spring and the first frost in autumn is the natural growing season for your region.
Tips for Zone 9-11:
Trees: Remove trees that are weak or rotted. Prune suckers and weak or damaged wood from trees. Shear fine-needled evergreens. Plant container and balled-and-burlapped trees. Plant dracaenas and palm trees. Install supports for newly planted trees. Water trees as necessary; deep watering is best. Newly or recently planted trees should be kept well-watered and shaded to prevent sunburn. Fertilize palm trees. Fertilize tropicals, subtropicals, and broad-leaved evergreens when they finish blooming. Weed soil around trees; apply preemergent herbicide. Apply summer mulch. Keep trees mulched to about one foot from the trunk. Watch for pests and signs of disease.
Shrubs: Remove faded flowers from shrubs. Prune spring-flowering shrubs and vines when they finish flowering. Prune bauhinia, oleander, and other tropical shrubs after bloom (use rubber gloves when handling oleander to prevent skin poisoning). Prune cassia trees, Poinciana, bougainvillea and jasmine after they bloom. Prune lilac, philadelphus, spiraea, and broom. Prune and removed dead blossoms from azaleas and rhododendrons. Prune suckers and weak or damaged wood from shrubs. Shear formal hedges. Train and prune vines as needed. Plant potted or bare-root shrubs and vines. Plant container-grown tropical and subtropical plants. Plant crotons, dracaenas, and large palm trees. Water new and established plants as needed. Feed and water established shrubs: camellias (acid food), Ixoras, Gardenias, Hydrangeas (acid food), and Tibouchina. Feed azaleas and rhododendrons with acid plant food every 6 weeks. Begin propagating azaleas and rhododendrons from cuttings after they finish blooming. Fertilize tropicals and subtropicals, and broad-leaved evergreens when they finish blooming. Weed around shrubs. Apply mulch for summer. Watch for pests and signs of disease. Check for thrips, caterpillars, ants.
Roses: Deadhead faded flowers. Disbud roses and other flowering plants for larger blooms. Remove side buds to encourage large single blossoms, or remove terminal buds to encourage clusters of blossoms. Remove suckers. Prune climbers and ramblers when finished blooming. Plant container-grown roses. Water as necessary. Water deeply during dry weather. Fertilize roses. Apply granular fertilizer or apply supplemental liquid fertilizer. Remove weeds around roses. Apply mulch for summer; aged compost is a mulch that feeds the soil. Watch for pests and signs of disease. Spray against insect pests. Continue spraying regularly with a fungicide and watch for black spot, mildew, and rust. Remove and discard diseased leaves.
Lawns and Ground Covers: Mow and edge the lawn as needed. Mow 1½ to 2 inches high; mow Bermuda grass to ½ inch. Lightly fertilize warm-season lawn grasses. Lay sod; plant plugs. If the lawn looks sparse, thin overhead tree branches, reseed with shade-tolerant grass or replace with shade-tolerant ground cover. Apply weed controls. Control broadleaved weeds by hand weeding or by using suitable commercial weed killers. Feed the law monthly; water the law weekly, twice a week when the temperature is greater than 90°F; sow dichondra seed. Prune ground covers as needed; shear low-growing plants. Cut back ornamental grasses to encourage new growth. Plant ground covers. Take ground cover stem cuttings for propagation. Layer ground cover stems for propagation. Remove weeds or apply an herbicide. Check for insects and diseases.
Perennials: Deadhead faded flowers and remove dead flower stalks from early-blooming perennials unless you want plants to self-sow. Thin out overgrown plantings. Pinch back chrysanthemums and dahlias. Pinch stem tips off chrysanthemums until mid-July. Prune back Arabis, Aubrieta, and perennial candytuft as soon as they have finished flowering. Divide and transplant summer- and fall-flowering perennials. Make notes for plants to order for fall planting to fill gaps in the blooming season. Make notes on which plants will need division in the fall. Check stakes on tall plants. Plant container perennials. Plant chrysanthemums. Sow biennials and perennials, including Aubrietia, Coreopsis, delphiniums, and wallflowers. Water if the ground is dry and if leaves are wilted. Weed and water as needed. Lay summer mulch in beds and borders. Mulch to protect roots from the heat with well-rooted manure, compost, or straw. Watch for pests and signs of disease.
Bulbs: Remove faded flowers. Remove foliage of spring bulbs when it yellows and dries. Dig, divide, and replant crowded spring bulbs. Divide and replant bearded iris. Stake up gladiolus, dahlias, lilies, and other tall-growing plants that have not bloomed. Plant summer bulbs. Water summer bulbs as necessary. Apply mulch for summer. Fertilize summer bulbs as they grow. Watch for pests and signs of disease.
Annuals: Cut flowers for indoor displays. Cut flowers for drying. Deadhead faded flowers promptly. Pinch back tall-growing plants. Remove hardy and half-hardy annuals as they fade. Shear low-growing plants.Plant tender annuals outdoors. Start another generation of zinnias, sunflowers, and marigolds for late-summer bloom. Sow biennials such as wallflowers and forget-me-nots. Sow hot-weather annual seeds. Continue planting tender annuals in bare spots and replace fatigued plants. Feed new seedlings with liquid fertilizer, older plants regularly. Thin seedlings planted earlier. Weed and water as needed. Be sure tall plants have stakes and annual vines are attached to supports. Watch for pests and signs of disease. Place snail and slug bait and protect seedlings from birds. Combat pests and fungal disease using organic means, applying insecticides and fungicides only if necessary.
Container Gardens: Deadhead faded flowers. Water containers as needed. Fertilize container plants regularly with a fast-acting liquid fertilizer. Provide supports for climbing plants. Watch for pests and signs of disease.
Tips for Zones 6-8:
Trees: Prune trees. Shear fine-needled evergreens. Prune suckers and weak or damaged wood from trees and shrubs. Remove self-sown seedlings of ash and sycamore before they become established. Remove trees that are weak, rotted, or tangled in utility wires. Plant container and balled-and-burlapped trees. Install supports for newly planted trees. Water and mulch newly planted trees. Weed soil around trees; apply preemergent herbicide. Keep trees mulched to about one foot from the trunk. Fertilize broad-leaved evergreens when they finish blooming. Watch for pests and signs of disease. Check for insects, diseases.
Shrubs: Deadhead and prune spring-blooming shrubs when they finish flowering. Remove flower heads from lilacs, laburnums, and late-flowering camellias as soon as the flowers fade. Prune suckers and weak or damaged wood from shrubs. Prune all spring-flowering shrubs that have finished blooming. Prune lilac, philadelphus, spiraea, forsythia, Ribes sanguineum, and broom. Prune spring-flowering shrubs after they bloom. Cut brooms back hard after flowering but avoid cutting into old wood. Prune deutzias cutting out flowered shoots. Pinch out flowers from senecios. Continue to deadhead azaleas and rhododendrons. Trim hedges of berberis, escallonia, hawthorn, and privet. Shear formal hedges. Train and prune vines as needed. Transplant shrubs. Plant shrubs. Water established plants if the ground is dry. Water new plants regularly. Continue to water newly planted evergreens during dry weather. Fertilize broad-leaved evergreens when they finish blooming. Feed and water fuchsias and hydrangeas – the latter with acid fertilizer. Feed azaleas, rhododendrons every 6 weeks with acid food; make tip cuttings and layers. Continue to weed and hoe hedge bottoms. Weed soil around shrubs. Keep the area around trees and shrubs clear of grass. Apply mulch for summer. Take softwood cutting for propagation. Layer long shoots of clematis and Japanese quince. Take cuttings of softwood or semi-ripe side shoots of clematis, cotoneasters, deutzias, fuchsia, and philadelphus and root in a cold frame or propagating unit. Take heel cutting of viburnums. Watch for pests and signs of disease on all shrubs and treat immediately.
Roses: Deadhead faded flowers. Disbud single–flowered bush roses for extra larger blooms and for cutting. Deadhead early-flowering shrub roses except those that produce good crops of hips later in the year. Remove side buds to encourage large single blossoms or remove terminal buds to encourage clusters of blossoms. Remove suckers from roses. Prune climbers and ramblers when finished blooming. Prune back lightly after June bloom; remove all old canes to the ground from ramblers; large-flowered climbers are pruned like Hybrid Teas. Buy and plant container-grown roses in flower. Soak roots thoroughly before planting, mulch after planting, and keep well-watered during the rest of the season. Water every 7 to 10 days. Water deeply during dry weather. Weed around roses. Apply mulch for summer; apply 2- to 3-inches of summer mulch. Continue to keep weeds at bay where no mulch was applied in the spring. Apply a rose fertilizer lightly once the main flush of flowering is over. Apply granular fertilizer. Apply supplemental liquid fertilizer. Watch for pests and signs of disease. Spray against insect pests. Watch out for signs of mildew and aphids on roses and spray promptly if they are found. Continue spraying regularly with a fungicide and watch for black spot, mildew, and rust. Remove and discard diseased leaves.
Lawns and Ground Covers: Mow and edge the lawn except in very dry weather. Continue to mow regularly. During drought, raise the mower blades and leave the mowing on the grass. This will help to conserve moisture. Spike established and new lawns deeply so that rain can penetrate to the roots. Continue to remove individual weeds with a spot or selective weed killer. Lay sod; plant plugs. Water weekly if the weather is dry. Water regularly with a sprinkler, but first, check to see if there are any local watering restrictions. Lightly fertilize warm-season lawn grasses. If necessary, apply nitrogen-rich liquid fertilizer to the lawn to make it greener and to encourage the grass to grow rapidly. Control broadleaved weeds by hand weeding or by using suitable commercial weed killers. Discontinue all weed killer treatments and feeding during dry spells unless you water regularly. Prune ground covers as needed. Plant ground covers. Fertilize ground covers. If lawn looks sparse, thin overhead tree branches, reseed with shade-tolerant grasses or replace with shade-tolerant ground cover. Take ground cover stem cuttings for propagation. Layer ground cover stem cuttings for propagation. Check for insects, diseases.
Perennials: Deadhead border plants regularly. Deadhead faded flowers unless you want plants to self-sow. Pinch back tall-growing late-blooming perennials to make bushy plants. Pinch out growing tips on chrysanthemums, dahlias, and pinks. Disbud border carnations. Pinch stem tips off chrysanthemums until mid-July. Prune back Arabis, Aubrieta, and perennial candytuft as soon as they have finished flowering. Shear candytuft and basket-of-gold. Cut early perennials back to near ground level after flowering. Lift and divide crowded clumps of border primulas as soon as flowering is over. Make notes on which plants will need division in the fall. Make notes for plants to order for fall planting to fill gaps in the blooming season. Stake tall-growing plants that have not yet bloomed. Plant container perennials. Divide and transplant summer- and fall-flowering perennials. Sow seeds of Achillea, Alcea, Aquilegia, Delphinium, Erigeron, and Lychnis. Sow for constant bloom, make monthly sowings this month and next of short-term bloomers like candytuft, nigella, and cornflower; sow seeds of Torenia to take place of pansies in the garden; sow perennial and biennial seeds in the frame. Sow biennials and perennials, including Aubrietia, Coreopsis, delphiniums, and wallflowers. Sow hardy perennials, sweet Williams, and wallflowers in an outdoor seedbed. Sow biennials such as wallflowers and forget-me-nots. Set out young chrysanthemum plants. Water all ornamental plants regularly to prevent developing buds from dropping off. Mulch moisture-loving plants with garden compost or shredded bark. Lay summer mulch in beds and borders. Feed perennials that have finished bloom, first removing dead flower stalks or stems. Feed, after bloom: delphinium. Lupine, Oriental poppies, aquilegia, peonies, and iris. Watch for pests and signs of disease. Watch nasturtiums for black aphids. Continue regular spray program. Take side-shoot cuttings of pinks and root in a cold frame. Watch out for sap-sucking insects and treat them with a systemic insecticide.
Bulbs: Remove faded flowers. Remove foliage of spring bulbs when it yellows and dries. Remove matured yellow foliage of tulips, dig and store bulbs for replanting in autumn. Transplant and divide spring-flowering bulbs. Divide May-blooming plants such as primroses, iris, and lily-of-the-valley. Dig and store bulbs that cannot tolerate wet soil in summer in a cool, dry location. Dig tulips and hyacinths after foliage yellows; discard bulbs or let dry in sun; remove dead leaves; store in a cool, dry place to replant in fall. When dry, clean the bulbs and store them in a cool, dry place until autumn. Apply mulch for summer. Finish planting gladioli and summer bulbs. Plant dahlias. Put stakes in place for tall dahlias, lilies, and gladiolus. Tuberous begonias may be purchased in pots now and set out in a shaded bed or patio. Mist with fine water sprays on hot afternoons. Water as necessary. Fertilize as they grow. Watch for pests and signs of disease.
Annuals: Cut flowers for indoor displays. Cut flowers for drying. Remove faded flowers. Pinch back tall-growing plants. Train vines and climbing annuals. Finish hardening off and planting tender bedding plants. Plant tender annuals outdoors. Direct-sow tender annuals in bare spots or set out new plants to replace fatigued plants. Pull up cold-loving pansies when they succumb to heat, and replace them with annual vinca, zinnias, or celosia. Pinch back tall-growing annuals to make bushy plants. Begin to thin out seedlings of any annuals sown directly into the ground. Plant up hanging baskets, barrels, and other containers. Sow sweet peas where they are to flower. Plant our sweet peas raised in pots. Thin seedlings planted earlier. Fertilize new seedlings with liquid fertilizer, older plants as they begin to bloom. Thin seedlings planted earlier. Weed and water as needed. Mulch flower beds. Watch for pests and signs of disease. Protect seedlings from birds. Combat pests and fungal disease using organic means, applying insecticides and fungicides only if necessary.
Container Gardens: Deadhead faded flowers. Pinch out growing tips of annuals to induce side-branching. Fill gaps in containers with annuals lifted from the garden. Move any planted-up hanging baskets outdoors. Turn hanging baskets regularly so that the plants develop evenly on all sides of the basket. Finish planting up containers. Water all containers freely – and daily – during hot, dry weather. Fertilize container plants regularly. Feed plants in containers regularly, unless slow-release fertilizer granules were incorporated before planting. Use a liquid fertilizer or special food for container plants. Provide supports for climbing plants. Watch for pests and signs of disease. Spray miniature patio roses against pests and diseases.
Tips for Zones 3-5:
Trees: Remove trees that are weak or rotted. Prune trees. Shear fine-needled evergreens. Fertilize trees with slow-release fertilizer as growth starts. Plant bare-root trees. Plant container and balled-and-burlapped trees. Install supports for newly planted trees. Water and mulch newly planted trees. Transplant trees. Remove winter mulch and burlap wrappings. Replace old mulch with fresh mulch. Weed soil around trees; apply preemergent herbicide. Apply summer mulch. Check for insects, diseases.
Shrubs: Remove burlap screens and winter protection. Prune spring-flowering shrubs after they bloom. Prune shrubs grown for their decorative winter stems, such as willows and dogwoods. Prune Forsythia as soon as it has finished flowering. Shear formal hedges. Fertilize shrubs as growth starts. Apply a high-phosphorous fertilizer around the base of summer-flowering shrubs, including roses. Layer shrubs and climbers such as Carpenteria, Fothergilla, Kalmia, Lonicera, and Syringa. Test soil pH around established shrubs and adjust, if necessary. Plant container-grown or balled-and-burlapped trees and shrubs. Transplant shrubs. Weed soil around shrubs. Apply mulch for summer. Check for insects, diseases. Remove faded flowers and shrubs. Water new plants regularly. Fertilize broad-leaved evergreens when they finish blooming. Deadhead and prune spring-blooming shrubs when they finish flowering. Watch for pests and signs of disease. Train and prune vines as needed.
Roses: Tie new, vigorous rambler-rose growth gently but securely to supports. Plant container-grown roses. Deadhead faded flowers. Remove side buds to encourage large single blossoms or remove terminal buds to encourage clusters of blossoms. Fertilize roses. flowers. Apply granular fertilizer. Apply supplemental liquid fertilizer. Water deeply during dry weather. Weed soil. Apply mulch for summer. Watch for pests and signs of disease. Spray against insect pests. Begin spraying regularly with a fungicide and watch for black spot, mildew, and rust. Remove and discard or burn diseased leaves.
Lawns and Ground Covers: Control lawn weeds, remove by hand, or use an appropriate weedkiller. Level off uneven areas of the lawn. Thoroughly prepare the ground to be seeded or sodded. Fertilize it with a complete fertilizer. Sow grass seed unless the soil is still very wet. Protect new seeds from birds and water regularly. Repair or replace worn-out or bare areas of turf. Lay sod; plant plugs. Mow and edge the lawn as needed. Water and feed the lawn regularly from now on. Keep up crabgrass and other weed-control measures. Plant ground covers. Plant annuals and perennial ornamental grasses. Take ground cover stem cuttings for propagation. Layer ground cover stem cuttings for propagation. Divide ground covers and perennial ornamental grasses. Prune ground covers. Remove weeds or apply an herbicide. Fertilize ground covers and ornamental grasses. Apply mulch for summer. Water as needed. Check for insects, diseases.
Perennials: Complete bed preparation. Sow perennial seeds indoors. Sow seeds of Achillea, Alcea, Aquilegia, Delphinium, Erigeron, and Lychnis. Set seedlings outdoors. Plant bare-root perennials. Plant container perennials. Plant out Antirrhinum and Penstemon raised from autumn cuttings or sowings. Thin out overgrown plantings. Cut back and feed very early-blooming perennials like myosotis, pansies, violas, and others. Pinch back late-blooming perennials like chrysanthemums, hardy asters, to make them bushy. Divide and transplant summer- and fall-flowering perennials. Fertilize perennials as they start to grow. Deadhead faded flowers. Thin out overgrown plantings. Cut back ornamental grasses. Stake plants. Apply summer mulch. Weed and water as needed. Lay summer mulch in beds and borders. Pinch back mums. Watch for pests and signs of disease.
Bulbs: Prepare beds for planting. Remove faded flowers from spring-blooming bulbs. Remove yellowed foliage. Set out bedding plants in bulb beds, but do not remove early bulb foliage, simply lay it aside to tie it together. Dig and store bulbs that cannot tolerate wet soil in summer in a cool, dry location. Apply mulch for summer. Plant summer-flowering bulbs after frost. Plant gladioli and summer bulbs. Plant caladiums, tuberoses, cannas, and other tender bulbs, corms, and tubers.Plant successions of gladiolus; plant other summer. Put stakes in place for tall dahlias and gladiolus. Fertilize when 6 to 8 inches tall. Weed and water bulbs as necessary. Deadhead faded flowers of spring bulbs; remove foliage when it yellows and dries. Dig and divide crowded spring bulbs.
Annuals Plant tender annuals outdoors. Harden off bedding plants in preparation for planting them in open ground. Direct-sow or plant out tender annuals when the danger of frost is past. Shade and protect newly set out annuals for a few days with berry boxes or shingles on the windy side. Fertilize new seedlings with liquid fertilizer, older plants as they begin to bloom. Thin seedlings planted earlier. Weed and water as needed. Deadhead faded flowers promptly. Watch for pests and signs of disease. Combat pests and fungal disease using organic means, applying insecticides and fungicides only if necessary. Train vines and climbing annuals. Mulch flower beds.
Container Gardens: Plant tender annuals in containers. Move plants kept indoors for winter back outdoors when the weather warms. Fertilize container plants regularly with liquid fertilizer. Water containers as needed. Deadhead faded flowers. Watch for pests and signs of disease.
