Frequent, shallow watering can result in moss in the lawn or new plants that die. Gardening expert offers advice to deliver the right amount of water.
You'd think that watering a garden wouldn't be too difficult. Yet many homeowners, even those with automatic sprinkler systems, don't understand how to irrigate their properties properly.
Landscapes often are watered too frequently and too shallowly and will yield signs of distress such as moss growing in the lawn, spots on leaves or new plants that die.
Plants grown in the Northeastern and Mid-Atlantic states, for example, are adapted to a climate where it rains for short periods followed by intervals of dry weather.
The average summer rainfall in New York City, Philadelphia and Washington, D.C., is around 4 inches per month, and Boston receives 3-and-a-half inches of precipitation. Given those amounts, it makes sense that the plants that do well here are different from those that thrive in the deserts where it's dry, or the rainforests where it pours like clockwork every afternoon.
Yet, far too many homeowners have automatic watering systems that are programmed to go off every day or every other day. Usually, this frequent watering lasts from 10 to 30 minutes, keeping the surface of the lawn and garden constantly damp, but allowing deeper roots to dry up.
This in no way emulates what nature provides in our region — it isn't right for the plants we grow.
Too much water is a contributing factor to every lawn disease and recurrent splashing of foliage causes leaf-spot fungi on shrubs and perennials. But automatic sprinkler systems aren't the only culprits. Hand watering can be detrimental to plants as well.
Although newly planted annuals or perennials can be watered by hand, established plants have deeper root systems and require us to stand there a long time before they get a good, deep soaking. For all but small, new plants, spraying the soil with a handheld hose is an inadequate way to water.
In times of severe drought, some municipalities enact watering restrictions that only allow hand watering. When this is the only irrigation that's allowed, so be it. Barring such local limitations, however, remember these words: a deep soaking less often is better than a little every day.
The next question to ask is how much is enough? In general, all our lawns and gardens need is an inch of water a week. Purchasing a rain gauge, so that you'll know how much Mother Nature has delivered, is helpful. That same gauge can be used to measure how much your sprinklers deliver, and you can arrange for your irrigation equipment to distribute that inch every seven days.
Summer temperatures in New York City, Philadelphia and Washington, D.C., can be beastly hot and humid in July and August. In such conditions, plants in full sun, or those that weren't watered deeply, may need more frequent irrigation. Boston tends to be a bit cooler, so unless temperatures really soar, a deep soaking once a week is sufficient. Remember — deep watering promotes deep root systems, but allow the surface of the soil to dry between soakings.
C.L. Fornari is a writer, gardening expert, professional speaker and radio host who is dedicated to getting you into the garden. The Osterville, Mass., resident is a member of the Perennial Plant Association, American Plant Propagators Society, National Speakers Association and Garden Writers of America.