Watering Alone Isn't Enough For Our Hot, Thirsty Plants


June 16, 1991|By Mary Gold

Standing over my heat-weary garden this week, hose in hand, I had a terrible flashback: the drought of summer 1988, outdoor watering restrictions and lost flowers and vegetables crops.

It's not even officially summer yet, and Howard County has suffered the hottest May on record. Cool-weather crops have come and gone in record time.

Most local gardens would be nothing but hard-baked cement at thispoint if it weren't for mulch and heavy watering.

A hot, dry spring doesn't necessarily mean a hot, dry summer, but many Howard Countygardeners are gearing up for that possibility.

Here are some tried and true drought defenses evident in local gardens and landscapes.

Bob DelFavero long ago gave up raised beds in his vegetable garden. He argues that although the beds might provide an early advantage by drying out quickly in the spring, summer weather here simply dries them out too rapidly.

He turned to planting in blocks, but doesn'traise them above the surrounding area. Coincidentally, the blocks are a more efficient arrangement to water than are long rows.

This is the first year in about 30 that he has not planted a garden, partlybecause he is so busy and partly because of the dry spring.

Deep watering two or three times a week is much more beneficial to plants than light daily watering.

Light watering encourages roots to stayat the soil surface where, come severe drought and water restrictions -- or your vacation -- they will die.

Deeply rooted plants will fare much better. Dig into the soil after you water next time and seehow far down the moisture has traveled. You may be surprised at how little has been absorbed.

Many gardeners dish the soil around large plants like tomatoes, or dahlias, so that water will pool around the base. Runoff is kept to a minimum.

Or they place large cans withsmall holes punched in the bottom near the plants. Filling each can with water at regular intervals (children like this job) supplies a slow, steady seepage of water where the plants needs it.

Irrigationspecialists at the University of Maryland have discovered that plants need more or less water according to their stage of development.

Beans, for example, will grow with a minimum of water until pod development starts. Then, for best results, regular watering is necessary.

Peppers, eggplants and cucumbers need water from flowering through fruit development.

Tomatoes need water during early flowering, fruit set and enlargement.

If water is uneven, seesawing between flood and drought during fruit growth, blossom end rot may occur. Thisis characterized by a black, sunken blotch at the bottom of each tomato. Melons likewise need regular water from blossoming on.

By now, the subject of mulch has been beaten into the ground -- and, hopefully, into our heads. There are too many good things about mulching toignore.

Most important, a mulch buffer of some kind between the soil and the air will slow evaporation of moisture that is normally drawn to the soil's surface.

A non-matting organic mulch such as weed-free straw, dried grass clippings or compost will not only help hold moisture, but when we do get a summer downpour, the mulch will minimize runoff.

Theresa Billow-Supple has covered her vegetable plot with 4 to 6 inches of straw for a fairly maintenance-free garden. Shechecks regularly under the straw and, even after a week of two without water, finds sufficient moisture just under the soil surface.

An added bonus, she notes, is that the mulch keeps most of the weeds down.

"Weeding is so easy," she says, "because the few weeds that do come up are easily pulled from the soft soil."

An organic mulch also keeps the soil temperature even, a boon for most vegetables and flowers.

As in the fall, the mulch can be tilled into the garden, or worked into the area around perennials, providing a great organic soil amendment.

Black plastic sheets, and related perforated or mesh landscape fabrics, are very effective as well. The regular black plastic should have some ventilation holes cut into it so that the soil can breathe and rainwater can enter.

Black plastic produces highheat underneath during sunny weather, a plus during the cool spring months but a minus during July and August. Plant roots will cook. Theplastic should be covered with an organic or light reflective mulch,or both, during summer.

Advancements in irrigation technology have filtered down to home gardeners in recent years.

Drip irrigationand porous hoses really do work in all kinds of situations -- in perennial gardens, around shrubs and in vegetable plots. These systems provide a slow, steady application of water that plants like best, andvery little water is lost to evaporation or runoff, as happens with sprinklers.

There are many types available, some of them expensive. The county library has several books on irrigation systems that interested gardeners should consult.

Protecting the home landscape ingeneral during a drought situation is a challenge. Which plants can withstand the stress and which cannot?

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