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Master Gardeners of Orange County, NC
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Bloom · Berry

Below is a simple ‘shortlist’ of plants that are normally in bloom this month or are of interest for fruit, bark or foliage. See Bloom • Berry for comprehensive lists with links to photos and cultural information.

Perennials Shrubs Trees Vines
coreopsis
dianthus
iris (bearded)
lady slipper orchid
peony
poppy
azaleas (Gumpo, Satsuki)
beauty bush
Scotch broom
candytuft
deutzia
mountain laurel
rhododendron (hybrids)
rose
weigela
dogwood (Kousa)
golden chain tree
magnolia (Southern)
clematis
honeysuckle

Lawns

Aeration

Aerify warm-season lawns (zoysia, bermudagrass, centipede) to loosen the soil and allow for better water and air infiltration.

Fertilizing

  • Do not fertilize tall fescue or bluegrass. Fertilizing these lawns after mid-March is counterproductive and merely causes stress.
  • For zoysia or bermudagrass, apply ½–1 pound of nitrogen per 1000 square feet several weeks after the lawn fully turns green (early April–May).

Mowing

  • Mow often enough so that no more than ⅓ of the grass height is cut, and leave grass clippings on the lawn. Clippings decompose quickly and can provide up to 25% of the lawn’s fertilizer. If grass clippings are too plentiful, collect and use them as mulch or let them dry a bit and add to your compost pile.
  • Mow fescue lawns to 3–3.5″.
  • Mow Bermudagrass when the lawn first turns green using a reel mower set at ¾–1″ or a rotary mower set as low as possible without scalping.

Insects

Check for white grubs.
White Grubs in Turf
White Grub Control in Turf

Seeding & plugging

Start warm season lawns like zoysia and Bermuda.

Weeds

The primary and most effective weed control tactic in a lawn is proper mowing. In fact, it has been estimated that regular mowing eliminates some 80 percent of weedy species.

— Michigan Cooperative Extension
  • Because the seeds of crabgrass and many other summer annual lawn weeds require light to germinate, keeping the turf dense and mowing no shorter than 3.5” (for cool-season lawns) reduces sprouting.
  • If you are using a pre-emergent for control, a second round of crabgrass preventer should be applied around May 15th.
    • Because cool-season lawns need to rest for the summer, use a product that does not contain fertilizers.
    • Products containing dithiopyr also provide post-emergent control for young crabgrass.
    • Crabgrass Control in Home Lawns

Links

Bermudagrass lawn maintenance calendar NC CES: AG-431
Tall fescue lawn maintenance calendar NC CES: AG-367
LAWNS our page

Ornamental plants

Disease

Be proactive about fungal disease. Fungicides should be applied when conditions favor disease development but before symptoms have appeared. Think of fungicides as vaccines that prevent diseases rather than curing them.

  • Warm, wet spring weather fosters outbreaks of cedar-apple rust, black spot and spot anthracnose.
  • Cool, moist springs encourage Entomosporium leaf spot.
  • To help dogwoods overcome diseases, keep them watered, maintain soil fertility, and clean up leaf litter to reduce disease pressure. See Dogwood Diseases & Insect Pests for details.
    • Spot anthracnose can be disfiguring, but our hot summers keep it from being a major problem.
    • Powdery mildew can distort the leaves and reduce the tree’s ability to make sugars for growth. The incidence of powdery mildew has increased recently in most states where dogwoods are grown and is a problem in our area.
  • Monitor camellias for leaf gall.
  • Spray red-tip photinia weekly if leaf spot is observed. Unpruned photinia seems to be resistant. If this is not an option, consider replacing your photinia with a more interesting selection of trouble-free shrubs.

Fertilizing

Fertilize summer flowering plants like crape myrtle and rose-of-Sharon if needed.

  • In general, if trees, shrubs and perennials are growing at a rate that is acceptable to you, the foliage looks healthy and bloom is plentiful, there is no need to fertilize.
  • Poor bloom can be a sign that a perennial needs division (e.g. daylilies, iris) or that shade or root competition is now a factor. Trees grow, and even if your bed is not shaded, tree roots often extend far past the drip line — sometimes 3X the diameter of the tree canopy.
  • Unhealthy foliage on any plant may indicate problems other than a nutritional deficiency. See FERTILIZING for more information.

Insects

Beneficial insects share the same plants as insect pests. Use low-toxicity pesticides when possible, spray only if needed, and spray at dusk when the bees have all gone home. Always read and follow label directions for safe pesticide application.

  • Aphids can attack tender new plant growth. They can be washed off with a forceful stream of water. Severe infestations can be controlled with the relatively environmentally benign insecticidal soaps.
  • Lace bugs also can attack new growth, usually only on azalea and rhododendron, but sometimes on pyracantha, cotoneaster, quince or hawthorne. Dark spots about the size of a pinhead on the lower leaf surface are diagnostic. The best defense is to plant genetically resistant varieties and to maintain plant vigor. For control of severe infestations where there is no evidence that natural predators are present, repeated applications of insecticidal soap or horticultural oil can be effective. When a history of lace bug infestation exists, insecticides can be applied to the lower leaf surface, usually 2 applications ~2 weeks apart. Monitor the plants about once a month for reinfestations.
  • Eastern tent caterpillars often attack young cherries or sourwoods or plants in poor health. Physical removal is an effective strategy — most will be in the tent on a rainy day or at dawn or dusk.
  • Monitor for cool season mites on junipers, arbor vitae, conifers, azaleas, hollies and camellias by holding a piece of white paper under a stem and vigorously shaking the foliage. Watch for specks smaller than a period on this page to begin moving. Damage (interior browning of foliage) is not seen until early summer, when the mites are no longer present.
  • Slugs can attack soft new growth. Holes in leaves or on leaf margins and a silvery slime trail in the morning indicate slug damage. Slugs hide under boards, stones or debris during the day, so populations can be reduced by managing habitat. See the link for additional suggestions.
  • Spray iris beds for iris borers.
  • Landscape shrubs may need to be sprayed for insect pests:

    Shrub
    arborvitae
    azalea
    boxwood
    euonymus
    hemlock, juniper
    pyracantha
    hybrid rhododendron
    Pest
    bag worm
    lace bug
    leaf miner
    scale
    spruce mites
    lace bug
    borers

Mulching

Opinions vary on summer mulch depth. A 1″ depth permits the mulch to decay over the course of the summer and minimizes the potential to trap too much moisture, which can lead to plant rot, but a 3″ mulch is better for conserving moisture and suppressing weeds. Ideally, adjust your mulch depth to reflect the current year's weather. Regardless, keep mulch away from plant crowns.

Planting & propagating

  • Plant summer annuals like begonia, geranium, marigold, petunia and zinnia.
  • Plant summer-flowering bulbs like gladioli (actually corms), cannas, callas, dahlias, caladiums and elephant ears.
  • Take softwood cuttings of plants like azalea, rhododendron, forsythia, clematis, chrysanthemum and geranium in late May.

Pruning

  • If needed, prune spring-flowering shrubs soon after they finish blooming. This avoids removing the flower buds for next year, which arise from growth that occurs this year.
  • All shrubs can be kept perennially young by removing some of the oldest branches at ground level each year: ⅓ of the branches of fast-growing shrubs, ⅕ of the branches of slow-growing shrubs. Prune to open the interior to light and air.
  • When cutting roses for the house or removing spent blooms, cut back only to the closest 5-leaflet stem. Removing too much wood and foliage when cutting flowers can seriously weaken rosebushes, especially during the first year.
  • Pinch back mums, zinnia, salvia, cockscomb (celosia), petunias, marigolds, snapdragons and garden phlox. Use your index finger and thumbnail to break out the lead growth at tips of branches. Pinched plants have shorter, sturdier stems, more lateral branching and more blooms. Continue pinching mums through early July. Pinching also works well for many vegetable plants, including tomatoes and peppers.

Sanitation

  • Pick off azalea and camellia leaf galls (white, fleshy growths) as they form.
  • Remove spent flowers, but leave the foliage of spring-flowering bulbs to replenish the bulb for next year. Don’t braid, tie or otherwise damage the leaves, just let them die down naturally. Plant annuals and perennials like hostas among the bulbs to help disguise unsightly foliage.

Staking

Stake floppy plants such as peonies, dahlias, and Boltonia (Michaelmas daisy) while small. After plants have grown large, they can be injured by staking and tying

Vegetables

Planning

  • Draw up a layout for your vegetable garden, keeping in mind the sun’s pattern and orient plants so that taller types don’t shade out shorter. Try to rotate vegetable crops so that the same varieties are not growing in the same spots year after year. A 5-year rotation is ideal to reduce plant-specific pest and disease populations, but even a shorter rotation period would be beneficial. See VEGETABLES for detailed instructions.
  • Consider potential soil contaminants in the area chosen for your garden, as well as for additions like compost and manure. Composted municipal yard waste often contains heavy metals and other contaminants and recently, herbicide carryover in compost, manure and some materials commonly used to mulch vegetable gardens has become a problem.
    Minimizing Risks of Soil Contaminants in Urban
    Herbicide Carryover in Hay, Manure, Compost, and Grass Clippings
    Certified Compost

Planting & transplanting

  • Transplant heat-loving vegetables like eggplant, pepper, tomato and sweet potato.
  • Plant seeds for beans, lima beans, cantaloupe, corn, cucumbers, okra, southern peas, pumpkin, squash and watermelon. These need a warm soil temperature (about 70°) to grow.

Tomatoes

Wait until tomatoes have set the first hand of fruit before fertilizing with 10-10-10 or other balanced fertilizer. Repeat in three weeks.

Spraying

Spray if insects are observed, or grow these under row covers to eliminate the need to spray:

cucumber
squash
tomato, eggplant
broccoli, cabbage, cauliflower
cucumber beetle
squash borer, aphids
flea beetle
worms

Fruits

  • Strawberries are ready for harvest now.
  • Fertilize blueberries, blackberries and grapes.
  • Continue spraying your tree fruits and bunch grapes with a fungicide program.

Landscape ideas

Plant vegetables and herbs in your flower beds.

  • Eggplants, peppers and cherry tomatoes make colorful additions.
  • Bush and climbing beans have attractive foliage and charming small flowers.
  • Herbs can provide a stately presence (rosemary) or serve as groundcovers (marjoram, thyme), accents (sage) or edging plants (chives).
  • Vegetables can also mingle with flowers in pots: Container Garden Planting Calendar for Edibles in the NC Piedmont
  • Consider some of the new dwarf blueberry varieties, but wait until fall to plant.

Links

Photo tours of the JC Raulston Arboretum
Spring-flowering bulbs SC CES

Houseplants

Move houseplants outside if desired.

Wildlife

  • Feed hummingbirds!
    • Most plants with tube-shaped flowers will attract hummingbirds. Note that cultivated hybrids often make much less nectar than wild strains.
    • Hummingbirds become abundant at feeders beginning in mid-July. Fill feeders with a solution of 1 part sugar in 4 parts water. Boil for 2–4 minutes to dissolve all sugar, then cool. Wash feeders and replace the food at least twice weekly.
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Lawn · Garden Moisture Index

Colors indicate inches of precipitation deficit/excess with a resolution of 4km.
Alabama State Climatologist Lawn/garden moisture index

This live feed maps the difference between recent garden-effective precipitation and the amount normally adequate for the time of year. Soil water-holding capacity is not considered, but the index still provides a good idea of current soil moisture.

Check drought conditions
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919 · 245 · 2061