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CRABGRASS CONTROL, PRUNING FLOWERING SHRUBS, AND WINTERKILL
I've received many calls recently about crabgrass control in lawns, winterkill, and pruning trees and shrubs. First, the crabgrass.
Crabgrass is a warm-season annual grass that grows best in the heat of mid-summer. Crabgrass over-winters as seed, comes up about mid-May or later, and is killed by fall frosts.
The best control for crabgrass and other weeds is a healthy, dense, vigorous lawn of Kentucky bluegrass and fine-leafed fescue. Another natural defense against crabgrass is to not mow grass too short. Mowing at 3-inch heights provides more shade at soil level, which reduces the ability of crabgrass to germinate.
If a pre-emergence weed killer is used to kill crabgrass seedlings as they germinate, it needs to be applied during the first two weeks of May. One application should provide season-long control. Always follow label directions, which usually specify applying 1/4 to 1/2 inch of water after application to move granules to the soil surface.
Be wary of lawn services that tell you your lawn needs five or more fertilizer applications. The most your lawn needs to be fertilized is three times, and two of those should be in early and late fall. Most lawns can get by with an application of fertilizer in late spring and another in the fall.
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There is no one time of the year to prune ornamental shrubs. Timing is most dependent on when a shrub flowers and whether it flowers on old wood or new wood. Old wood is wood that has gone through at least one winter; new wood is the part of the branch that has grown in the current growing season.
Shrubs that bloom early in the growing season on old wood (azaleas, forsythias, lilacs and Juneberries) should be pruned immediately after they finish blooming.
Shrubs that flower later in the year on old wood (mockorange, potentillas, roses and weigela) should be pruned before growth starts in the spring or after blooming Shrubs that flower on new wood (clematis, Annabelle and PeeGee hydrangeas, Anthony Waterer spirea) should be pruned before the growing season begins. Prune these shrubs to the first pair of buds above the ground.
Fruit-bearing shrubs like barberry, dogwood, honeysuckle and viburnums should all be pruned in the spring before growth starts.
The best way to prune most shrubs is to completely remove the oldest one-third of branches each year. Removing the entire branch is better than just trimming the tips because it allows leaves to grow throughout the entire plant. Removing just the tips around the entire shrub causes overgrown plants that have leaves only on the outer branches and remain bear in the center.
Junipers, arborvitae and yews can be pruned at any time, although early in the growing season is best. Evergreen shrubs in the pine family (e.g., Mugho pine) can only be pruned when they are at their candle stage in the spring. New candles can be cut back by one-third to one-half their length. Cutting past the candle or pruning at the wrong time will result in dead stubs.
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Once again this spring, many pines, spruce, yews and arborvitae are exhibiting a lot of brown from winterkill. Keep an eye on the brown areas this spring. If no green growth occurs by June, this part of the plant is most likely dead and will need to be removed. Some needles that are still partially green may recover once juices began flowing within the plant.
The best prevention against winterkill is to plant hardy varieties in the first place, and then to mulch young trees and shrubs in the fall, keep plants well watered right up until the ground freezes, and avoid fertilizing plants after the first week of August (to discourage late-season growth spurts).
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PUTTING DOWN ROOTS:
A Delightful Blend of
Gardening Wisdom, Wit
and Whimsy
$10 + $2 for shipping
by Cliff Johnson |
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