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.
Rose (Lady Banks)
- 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).
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, dry them a bit and either use them as mulch or add them to your compost pile. Grass clippings are high in nitrogen, so balance them with shredded leaves or other high-carbon items.
- 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.
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” (cool-season lawns) reduces sprouting.
- Because spring weather varies, it is best to use flowering as a cue for when to apply pre-emergent crabgrass control to exposed areas
such as lawn edges. Apply while forsythia is blooming, then reapply about 6 weeks later.
- 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
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, cedar-hawthorn and cedar-quince rust, black spot (see roses) and spot anthracnose (see dogwoods).
- Cool, moist springs encourage Entomosporium leaf spot. While common on red-tip photinia and Indian hawthorne, it can infect many plants in the rose family, such as flowering and fruiting pear, firethorn, hawthorn, serviceberry and quince.
- 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 on dogwoods, 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.
- Monitor for diseases and insects. If you plan to spray, begin as soon as first leaves appear. Better yet, plant one of the tough shrub roses that require little or no spraying. Look at Cooperative Extension rose trials whose goals are good landscape performance without spraying or supplemental water: Texas, Tennessee, NC.
- Be careful to avoid stimulating growth before reliable warm weather arrives, because new growth is especially sensitive to cold damage. It is safest to use slow-acting fertilizers, because these require warm soil to begin working.
- Consider whether fertilizer is 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 — often 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.
- Fertilize established roses when new growth is approximately 2” long.
Frost & freezes
- Bulbs. A hard freeze can injure daffodil blooms (iris blooms are much more tolerant) but will not harm the bulbs. If a hard freeze threatens, cut some flowers to enjoy indoors.
- Fruits. Species like peaches and blueberries with low chill requirements (the number of hours between 32°F and 45°F)
are susceptible to spring frost because once the chill requirement has been satisfied, a short spell of warm weather induces buds to swell
and open. The extent of cold damage depends on the stage of bud formation.
- Freezing is not entirely bad, as most fruits profit from some thinning. Also, some fruit trees have latent buds that will swell and blossom if other buds have been frozen.
- To delay bud break during a warm spell, use a sprinkler to mist your tree during the day. Misting can reduce daytime temperature by 10–15°F. The heat required to evaporate the water is taken from the bud, which prevents the hormonal changes that initiate bud development.
Dormancy and how to maintain it
AgroClimate Chill Hours Calculator
- 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, arborvitae, 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.
- New mulch. Mulch used to conserve moisture and suppress weeds is best applied after the soil has warmed up in the spring. Cool, wet soils can slow seed germination, increase the decay of seeds and seedlings and increase disease pressure in perennial beds.
- Old mulch. To stimulate plant growth once our cold snaps are past, rake away the mulch to allow the ground temperature to increase. When plant growth has begun, the mulch should be returned to a depth of about 3”, keeping it away from plant crowns.
- You can continue to plant perennial groundcovers and some trees and shrubs. Most trees and shrubs would prefer planting late next fall or winter so that root repair can occur without the stress of top growth, but slow-growing, fleshy-rooted woody plants like magnolias and camellias are good candidates for spring planting.
- Sow hardy annuals, scattering seeds directly where you want them to grow. The best germinators in cold, moist soil are annual phlox, Centaurea cyanus (bachelor’s button or cornflower), calendulas, Viola cornuta, Consolida sp., Nigella damascena (love-in-a-mist), Portulaca grandiflora (moss rose) and Lobularia maritima (sweet alyssum).
- Wait to plant summer annuals until after our average last frost date (April 15 ± 12 days). Remember that microclimates in your yard affect whether they will experience frost — see FROSTS for details and tips.
- Divide late summer- and fall-blooming perennials as the tips emerge. Spring- and early summer-blooming perennials, including hostas, are best divided in autumn. If dividing hostas in spring, wait until the first flush of leaves has hardened since new leaves are especially prone to dessication stress.
- Hardwood cuttings of many landscape plants like forsythia, flowering quince, weigela, crape myrtle, juniper, spirea and hydrangea can be taken this month.
- Trim back ornamental grasses, mondo grass and liriope before any new growth begins, or let hungry rabbits trim your liriope and mondo grass for you.
- 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. Young shrubs may not require pruning, but note that shrubs can be kept perennially young by removing some of the oldest branches at ground level each year — 1/3 of the branches of fast-growing shrubs, 1/5 of the branches of slow-growing shrubs. Prune to open the interior to light and air.
- Remove leaves from your beds to prevent them from smothering new foliage and rotting plant crowns and bark.
- 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.
Test your soil if you have not done so for two or more years. The test is free for April–November. Take several core samples from over the area to be tested, mix them together and fill the sample box. Sample boxes, detailed instructions and submission forms are available from the Cooperative Extension office and some local retailers.
Keep landscape plants watered. Cold, dry winter winds quickly remove moisture from the soil and plant tissues. Newly-planted plants are especially susceptible to drying. The only way to know when a plant needs water is to check the soil around its roots. Dig a few inches into the topsoil. If the soil is dry, water is needed. Watering just before a cold snap can help plants survive bitter temperatures.
Apply pre-emergent weed control for annual weeds by the time dogwoods are in bloom. Spray wild onion, wild garlic and winter annual weeds with a broadleaf herbicide. Follow the label directions carefully. Note that most of these products work best when air temperature is between 50–80°F.
- 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
- Draw up a layout for your vegetable garden. Keep the sun’s pattern in mind 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.
Planting and transplanting
- Hardier vegetables like beets, radishes, turnips, leafy greens, carrots, broccoli, cabbage, cauliflower, potatoes, and asparagus can be planted in early April, but wait until the end of the month to plant tomatoes, peppers and eggplants.
- Start seeds of hot-season crops like corn, beans, melons, cucumbers and summer squash after the frost date (April 15th).
Disease & insects
- Spray all fruit trees with dormant oil to help eliminate some insects.
- Monitor for fireblight on fruit trees from the rose family (apples, crabapples and pears). When choosing trees to plant, select genetically resistant varieties.
- Once fruit trees have finished blooming, use preventive strategies to minimize insect and disease problems.
There is still time to prune blueberries, blackberries, grapes and fruit trees.
- Blueberries. Remove old canes at the base. Prune vigorous shoots to 4–5 feet to promote branching and to ease harvesting. Small basal shoots can be removed (and transplanted if desired).
- Blackberries. Cut side shoots back to 12–14 inches to keep the fruit close to the strong main stem. Remove any remaining dead or weak canes and all sucker shoots farther than ~12 inches from the crown.
- Fruit trees should be pruned yearly. The goal is to develop a structure with well-spaced branches (to reduce the likelihood of disease and to ease harvesting) that all have good exposure to sunlight (to maximize fruiting). While pruning is usually done earlier in the season, trees will tolerate pruning up until growth initiates from buds.
- Expect deer and rabbits to look for food in your garden as their natural forage is scarce. Azaleas, camellias, yews and pansies
are at risk, as well as other evergreen plants. It is very difficult to deter hungry deer, so the best protection is exclusion — a fence
or “cages” made of wire fencing placed around individual plants. Deer-repellent sprays may be helpful, but are best used before
browsing has begun and should be varied through the season to ensure that deer don’t learn to ignore the scent/taste. Most need to be
reapplied after a rain.
Reducing deer damage [SC CES]
Minimizing deer damage first slide deceptive, discusses all aspects of deer management[Pender County]
Managing deer damage in Maryland comprehensiveMD CES
- Welcome back hummingbirds!
- Hummingbirds usually return by the beginning of April.
- 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.
- Enjoy spring-blooming perennials. Most woodland plants bloom before the tree canopy excludes light, but some sun plants bloom this early as well. Use BLOOM · BERRY to find plants of interest. Each link has photos & plant information.
- Shop for plants, but do some research before committing them to the ground.
- Look for key phrases like “heat resistant” or “tolerates humidity” to help decide whether a plant will perform well here.
- Check hardiness zones. If zone 7 (our zone) is one of the limits, e.g. “zones 3–7” or “zones 7–9”, consider planting in a microclimate in your yard to ensure viability during extreme winters or summers.
- Because of financial pressures, many new varieties are rushed to market without adequate testing for performance under real-world garden conditions, in multiple geographic locations or for long enough to assess resilience in the face of weather vagaries. Talk to Master Gardener Volunteers for information on plants that are well-adapted to our area and consult ORNAMENTALS for detailed lists of suitable choices.
- Design a native garden.
- Start feeding houseplants again.
- Watch for indoor insect pests. Most can be controlled easily with insecticidal soap.
Lawn · Garden Moisture IndexColors indicate inches of precipitation deficit/excess with a resolution of 4km.
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