Baby, It’s Dry Outside

Baby, It’s Dry Outside

As noted on last week’s Landscape Message from the University of Massachusetts, “The past two weeks have been a trifecta of heat, humidity and insufficient rain.” The topsoil and subsoil are dry, and all over the Cape people are noticing curled Rhododendron foliage, wilted Hydrangeas, and browning perennials. Even plants that have been under irrigation are showing signs of drought stress.

When a plant’s leaves curl like this, you know it’s dry!

Here’s what home-owners can do:

Water deeply but less often. Twenty minutes every other day usually only dampens the soil a few inches down. If you’ve got automatic irrigation, wait an hour or two after it’s finished and take a trowel to dig in the area that was just watered. Look to see if the soil is moist ten to twelve inches down. If not, adjust your irrigation so that it’s on for longer, but isn’t coming on as frequently. Even in a drought it’s possible to give plants too much water.

This is a lawn that was under drought stress so the homeowner started watering it three times a day, including in the evening. This resulted in the mold you see growing on this turf, doing further damage.

Even lawns benefit from a deep soaking but less often. If the surface of the soil is kept constantly moist, you can develop fungal diseases and promote growth of moss.

Recognize that lawns don’t grow as actively in hot, dry weather. Don’t fertilize, and mow high to keep them as healthy as possible.

If you’re needing to water plants know that it’s far more effective to use a sprinkler so that the entire area gets watered. Most people aim the hose at the base of the plant when hand-watering, leaving the majority of the roots dry. Roots usually extend beyond the drip-line, so that’s where water should be evenly distributed. Water in the morning whenever possible, so that foliage drys during the day.

Hydrangeas are the first shrubs to show drought stress in this area. For this reason they shouldn’t be planted in areas that don’t get watered…there are other, more drought-tolerant plants that do better in dry soils, including our native bayberry.

Recognize that some plants tolerate drought better than others. Note which plants need less water (spirea, junipers, sedum, Baptisia, bayberry) and plan to group these together in the future. Group plants that like more water (roses, hydrangeas) in the same area so that your irrigation is going to the plants that need it most.

It’s natural for thirsty plants to lose the older, lower foliage as they put the limited water into the newer growth. If you see plants with older leaves that are turning yellow or brown, it’s most likely due to the drought.

Cut any perennial down that has turned brown from the drought. They should return next year or even put up new foliage later in the summer.

An application of compost spread around a stressed plant can do wonders when combined with a deep soaking. Compost helps keep moisture in sandy soils, and amends from the top down. You can spread compost over mulch, or put a one inch layer of mulch over the compost.

Cut perennials that have dried down to about two inches from the ground.
Humid air in combination with drought is the perfect conditions for powdery mildew to thrive. If you want to stave off mildew as long as possible, spray with an organic fungicide such as Revitalize now.
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