Growing Vegetables in Drought, Desert and Dry Times (Sasquatch Books, 2015) by Maureen Gilmer proves that even in times of drought, or in the middle of the desert, gardeners can still help their plants thrive. Gilmer’s guide focuses on four different low-water conditions across the United States; water conservation, drought, high deserts, and low deserts. In the following excerpt, she explains how using row covers can improve your garden.
When you create a tunnel-like greenhouse over your garden rows, you use a row cover. Row covers have so many benefits that once you start using them you’ll wonder how you ever gardened without them. Here is how a row cover can solve many food-garden problems:
• It can protect plants from cold damage. Use it to start seedlings in the garden while nights are still frosty, or to help mature plants live outdoors through the winter for year-round vegetables.
• It can shelter plants from high-UV sun damage in the desert.
• It can help conserve water. When you water a plant under a row cover, moisture in the soil gradually evaporates into the air. When there’s a row cover present, the rising moisture lingers to humidify the air immediately around the plants, mitigating effects of low-humidity conditions and evaporative water loss.
• It protects against dry wind. Young vegetables are susceptible to desiccation from dry winds, and sensitive older plants are too. A row cover eliminates the need to create a windbreak for the whole garden by providing temporary or permanent smaller scale applications.
• It seals off plants from insect pests. Organic gardeners who do not use pesticides use lightweight row covers to create a “screen porch” for their vegetable crops. They are particularly useful for preventing whiteflies, aphids, and spider mites, which are very difficult to control. This is one of the best preventative tools for pest management.
Row covers for insect control have one drawback: they control all insects. This denies pollinators access to your plants, which prevents pollination of crops that depend on flowering, such as peas or peppers. This is why row covers are often used early in the plant’s life span for a pest-free start,
then are removed when plants flower to allow for pollination. If they are to remain in place during flowering, roll up the sides and open the ends to allow pollinator entry.
To allow the row cover to be rolled up for bed access and venting, some gardeners sow a sleeve on the long edge of each row cover and slide a piece of PVC into it. This allows it to roll up easily, be tied into place for the day, then rolled back down again for frost protection. Another trick is to use strong, high-quality wooden clothespins to temporarily hold row covers out of the way when working inside or as clamps for excess fabric in windy weather.
Types of Row Covers
If your row cover was big enough, it would become a tunnel greenhouse! That’s why it’s best to consider them portable and temporary greenhouses in your garden. A row cover is composed of hoops and a cover sheeting that is made in different ways to serve a variety of purposes. For example, sheeting designed strictly for pest control will be a fine mesh that allows 100 percent of the sun to penetrate with free air flow while preventing even the smallest bugs from penetrating. On the other hand, plastic row covers designed strictly for frost protection are heavy-gauge, solid sheeting with high insulation values.
A row cover is composed of two elements: hoops and cover sheeting. Here are some variations:
Flexible Hoops: Pressed into the soil for anchorage on each side to span a row or a series of closely spaced rows.
Prefabricated metal hoops: These hoops are sold specifically for row covers, preshaped for different-sized arches. Often two hoops are used together to sandwich the row cover between them for better support, which is helpful in high wind coastal or desert regions.
Homemade PVC hoops: Save money by using 1/2-inch PVC to create your own hoops. This is a great way to create a small greenhouse too.
Single hoop with Snap Clamps: You can buy plastic Snap Clamps that snap around your PVC hoop to hold the cover tightly. These and other sheeting attachment fittings are sold in the row cover supply sections of most gardening catalogs. Clamps are a wise choice for windy regions where row covers are easily blown out of place.
Cover Sheeting: Row covers are typically composed of spunbonded polypropylene that’s resistant to tearing and manufactured with different characteristics. Each one will be rated by its frost protection, light transmission, and weight. For example: Agribon AG-19 Floating Row Cover protects to 28 degrees Fahrenheit, allows 85 percent light transmission and weighs 0.55 ounce per square yard. Row covers by Agribon and other manufacturers can offer many different light and frost protection ratings within each of these five basic definitions.
Tunnel Row Cover
The standard row cover is also spun polypropylene but it’s stronger, lasts longer, and offers some frost protection. This type is more dense, filters a greater amount of UV light, and may be removed and stored for years if well cared for. The medium- and heavyweight row covers require hoops to support the fabric so it does not crush plants or their flowering tips.
Floating Row Cover
The most lightweight row cover, it is made of insect netting or spun-bonded polypropylene or polyester. It is so lightweight that it lays right on top of plants, rising as they grow, until the plants are mature enough to be exposed for pollination. This cover is also used on arching supports of wire mesh or PVC arches. These row covers have a shorter life span, sometimes lasting just one growing season.
Tips: Excellent row cover installation videos and articles, as well as professional assistance, are available at groworganic.com.
The advantage to using woven row cover is that it’s easy to repair if it’s damaged or ripped. Keep dental floss and a mattress needle on hand to patch holes or close rips in a timely fashion before crops or the rest of the fabric is damaged.
Use an anchor trench for row cover installation in windy areas. An anchor trench is a simple but effective means of securing geotextiles to slopes for erosion control or to anchor the irregular edges of garden pond liners. Simply dig a trench and lay the single layer of fabric into it and out the other side. Next, pack the trench with excavated soil. Finally, fold over the excess fabric and cover it with soil. When all the material is underground, it won’t flap in the wind or catch on equipment, which can tear or loosen the fabric and cause trauma to the tender plants underneath.
Floating Row Cover Installation (No Hoops)
Supplies: Row cover fabric, staples.
1. Plant your bed in advance with seedlings or seeds.
2. Select a calm day for row-cover installation.
3. Unfold the row cover adjacent to the bed.
4. Cut to fit the bed’s length.
5. Drape over the bed loosely.
6. Secure to the ground every 6 to 8 feet using staples, nails, or rocks, or use an anchor trench. Leave plenty of slack to allow for growth.
Tunnel Row Cover Installation (with PVC Hoops)
Supplies: Row cover, hoops or PVC, rebar, garden staples, clamps.
1. Pound two pieces of rebar into opposite sides of the bed at a slight angle toward the center. Leave 6 inches exposed.
2. Slide PVC down over each rebar to create a hoop.
3. Repeat steps 1 and 2 for every 5 linear feet of tunnel.
4. Cut a piece of row cover measuring 8 feet longer than the length of the bed.
5. Lay out the row cover, allowing 4 feet extra on each end.
6. Clamp row cover snugly to both sides of each hoop.
7. Bury the edges of the row cover along both long sides of the tunnel, or stake into place.
8. Gather the loose end material and tie it with a cord.
9. Pound a stake into the ground and securely tie the cord to this anchor.
Tip: In the desert, where high UV weakens PVC, use metal electrical conduit or 4-foot-by-8-foot panels of welded wire mesh used for concrete slabs for greater longevity and strength.
Row Cover Supply List (Per 5 Linear Feet of Tunnel)
• Two 18-inch pieces of 1/2-inch rebar (find in the masonry department of a home improvement store)
• Lengths of 3/4-inch PVC pipe, 7 feet long (plumbing department)
• Supply of 3/4-inch row cover clamps, two to four per pipe (order online)
• Row cover long enough for overall length of bed (order online)
More from: Growing Vegetables in Drought, Desert and Dry Times
© 2015 By Maureen Gilmer. All rights reserved. Excerpted from Growing Vegetables in Drought, Desert & Dry Times: The Complete Guide to Organic Gardening without Wasting Water by permission of Sasquatch Books.