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Miracle blankets for vegetables?

Miracle blankets for vegetables?

Like a warm blanket on a cold day, floatingrow covers make life easier for plants when the surroundings are less than ideal. Laid over vegetables at planting time, they serve as miniature greenhouses, trapping heat, warming the soil, and boosting growth while keeping out pests.

Used properly, they can improve germination,lengthen the growing season, hasten harvest dates, and boost yields. They might even let you grow vegetables that aren't normally successful where you live.

It's an approach that takes some gettingused to. Covering up your newly planted vegetables so you can barely see them may not be easy at first, but the benefits can be impressive. Though universities have been testing floating row covers for three or four years with dramatic results, this will be the first spring a variety of materials will be available to home gardeners.

We arranged tests of the five floating rowcovers described on page 88 at five different gardens around the West. The results are summarized on page 90.

Each material is extremely lightweight,transmits 80 to 95 percent of the sunlight that strikes it, and lets water pass through. You can buy most kinds in rolls 5 to 6 feet wide and up to 375 feet long.

You simply lay the covers over 1- to 3-foot-widerows of vegetables and secure the edges. Floating right on top of the plants, they bulge as the plants grow.

Trapped heat gives plants a boost inspring. You can use the covers in early spring, when the soil is cool. By trapping the sun's heat, they'll raise soil temperatures 5| to 10|. If you plant through a black plastic mulch, you can build up even more heat.

In most parts of the West, this extrawarmth lets you plant up to three weeks earlier in spring, speeds growth, and yields more consistent and faster germination of direct-seeded vegetables. Earlier planting means earlier harvest and often bigger yields. If you live in an area with short growing seasons or cool summers, the extra heat can mean the difference between success and failure with many warm-season vegetables.

Trapped heat extends harvests in fall. Coveringwarm-season vegetables, such as tomatoes and peppers, before the first fall frost will provide some protection--but more importantly it adds the heat needed to help ripen remaining fruit. The covers can also keep cool-season vegetables growing later into autumn.

Depending on the thickness of the materialand growing conditions, row covers provide at least 2| to 3| of frost protection.

Covers provide a barrier to pests. Rowcovers can help exclude insects, diseases transmitted by insects, and marauding animals such as birds. But once insects, such as aphids, get under the covers where it's warm and they are protected from predators, they flourish--and eliminating them is more difficult while the covers are in place. One gardener controlled aphids on her plants by releasing ladybugs underneath the row covers.

To help prevent insect infestations, startwith plants that are free of insect eggs or larvae, and lift the covers only when you have to.

You can choose for warmth or durability.Covers differ in their durability and their ability to trap heat.

The microperforated polyethylene (Vispore)and spun-bonded polyester (Reemay) are the most durable--good choices if you plan to use the covers for more than one season or you live in a windy area.

The microperforated polyethylene kindprovides the most warmth. If you're planting warm-season vegetables that benefit from more heat or if you're planting cool-season vegetables much earlier in spring than normal, it could be your best choice, particularly in cold or wet climates. In warm climates, you're better off with a lighter point-bonded material, such as Agryl P17.

Preparing the beds is routine. Preparebeds as you would for a normal vegetable garden. If you use 5- to 6-foot-wide row covers on tall- or wide-growing plants like broccoli and melons, make rows 1 to 1 1/2 feet wide, so there is enough slack under the cover for plants to grow. Lowgrowing plants like lettuce and radishes don't expand as much, so you can make these rows to 3 feet wide.

When you drape on the covers, gather theexcess material in the center of the row, to give plants room to expand. If you don't need to lift covers to control weeds (see below), the best way to hold down edges is to bury them with soil.

If you need to lift the row covers periodically,it's more convenient to hold down edges with 2-by-4s. Make sure the ground is fairly level so the boards hold the edges flat. If there's a gap, insects can get through.

Weeds can be a problem. Weeds canthrive in the warm environment under a row cover. For widely spaced plants like broccoli, cauliflower, cucumbers, and tomatoes, your best defense is to lay black plastic mulch on top of the soil before planting and bury the edges with soil.

With closely spaced, direct-seeded cropslike beets, carrots, and radishes, lift one side of the row cover and pull weeds as soon as they appear.

How do you handle watering? All rowcover materials are permeable to water, so you can water plants with a sprinkler or a hand-held hose. (This works better than you might expect.) Young plants may be weighted down slightly afterwards, but once the fabric dries, they'll pop back up. For new transplants, remove covers during prolonged periods of heavy rain.

If you use black plastic under the rowcovers, form a basin around each plant so water runs toward it, or punch small holes in the plastic.

An easier way to water under row coversis to use drip irrigation or soaker hoses. This may also save water, since during overhead irrigation some water tends to run off the material. Install drip tubes or soaker hoses before laying black plastic.

When do you remove the covers? To decide,you'll need to monitor plant growth and the weather. Some guidelines:

--In general, unless you're planting unusuallyearly or you live in a climate that can have frosts anytime during the growing season, it's best to leave covers on only four to six weeks in spring. In frost-prone areas, you can use them all season (pull them back on hot summer days and to allow insect pollination where needed).

--Since warm-season plants like cucumbersand melons must be pollinated by insects, take off the covers when these plants begin to flower.

--As they billow in the wind, row coverstend to scuff foliage, making leafy vegetables look somewhat battered. If you remove the covers when plants are still young, only older leaves will be scuffed, and these are usually discarded anyway.

--In all cases, to prevent heat damage toyour plants, remove or pull back covers when the weather turns really warm. When temperatures climb into the 80s, it can be 30| hotter under the covers.

--In fall, cover warm-season vegetablesuntil the plants have finished producing. Keep cool-season crops covered until harvest time.

Where to buy floating row covers. Youcan order them from the following suppliers. Shipping usually costs extra. Call for details, or write for free catalog.

J.M. McConkey & Co., Box 309, Sumner,Wash. 98390; (206) 863-8111. Sells Agryl P17.

McCalif Grower Supplies Inc., 2215Ringwood Ave., San Jose, Calif. 95131; (408) 946-5773. Sells Vispore.

Mellinger's, 2310 W. South Range, NorthLima, Ohio 44452; (800) 321-7444. Sells Kimberly Farms, Reemay.

Territorial Seed Company, Box 27, Lorane,Ore. 97451; (503) 942-9547. Sells Agronet, Reemay.

Photo: Billowing spun-bonded polyester row cover is draped over fall-planted lettuce to trap heat and hasten harvest

Photo: Taking a quick look, gardenerchecks development of vegetables under a row cover. In this plot at Menlo Park, vegetables growing under five different covers were tested against the uncovered row

Photo: Row covers speed growth. In Sunset garden,"Ambrosia' muskmelon outgrew its cover five weeks after planting, while control (foreground) was just getting started. At far right, covered melon was ready to harvest a month earlier than the control

Photo: Overhead watering temporarily mats downcovers over young plants, but covers dry quickly. Boards weight down edges

Photo: Bury edges of fabric with soil to securecover and keep out insects. Slack in center gives plants room to grow
COPYRIGHT 1987 Sunset Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1987 Gale, Cengage Learning. All rights reserved.

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Date:Feb 1, 1987
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