December 05, 2021 3 min read 0 Comments
The use of covers has become an increasingly popular option for growers searching for chemical-free ways to manage weed pressure and exclude insects. On many market farming operations, the use of covers is a vital aspect of the systems of production. Here, we break down the most commonly used covers and how to use them.
Ground covers are protective coverings placed directly onto the ground to provide a barrier for weeds and soil retention. The two most common types of ground covers used in intensive farming systems are silage tarps and landscape fabric.
Silage tarps are made of UV-treated poly plastic. The tarps are often used as a form of weed management. The plastic creates a moist and warm environment, perfect for seed germination. The tarp deprives the new growth of light. The newly emerged seedlings become "leggy" and weak. After removing the tarp, easily cultivate the area with a hoe or burn with a weed burner.
This method of tarping is an old French farming practice referred to as occultation. It has seen a revival with the help of farmers like Elliot Coleman and Jean-Martin Fortier. Occultation creates a 'stale seedbed' where weeds' seed bank has already been severely depleted before a crop enters the soil.
Landscape fabric is used both as a form of mulch and as a covering for garden areas for weed suppression and pathways. The fabric is made from woven polypropylene plastic and can come in many variations of strength, UV resistance, porosity, and durability—the tighter woven plastic of the 5 oz. Heavy Duty Landscape Fabric works very well for walkways, in high tunnels, and in-between rows. Use the fabric as a template for plant spacing. Burn the designated holes for plants, instead of cutting, as this prevents fraying.
Frost blankets are commonly used for protecting plants from cold weather and for pest protection. They are made from spun-bonded polypropylene. The porous design allows air, water, and nutrients to pass through and allows for varying degrees of light transmission.
Frost blankets provide 10+ degrees of freeze protection. The thick material only allows for around 40% light transmission. This type of blanket is used to protect cold-hardy crops like brassicas from winter damage.
Row covers are a lighter, spun-bonded polypropylene cover used to protect plants as they establish. They offer less frost protection but are perfect for germination and light coverage. Row covers significantly increase germination rates compared with the use of other mulching techniques like hay or straw. Cover the bed with the fabric after direct seeding and water them in. The fabric helps to retain the moisture level while the new seedlings grow.
The cover allows water and air to flow through while helping to retain moisture levels in the seedbed. The fabric also protects from direct sun exposure.
Insect netting is designed to be a protective barrier for plants against pests. High-quality insect netting is often the first line of defense against pest pressure and can also be a tool for containing beneficial insects and pollinators. The mesh netting comes in different sizes to exclude or contain certain insects. Mesh sizes are measured by the number of holes per linear inch of fabric.
Netting should be installed immediately after transplanting or seeding. Install using row cover support hoops or drape directly onto the plants. Be sure to completely seal the edges of the netting using rocks and soil to prevent gaps.
Proper care and storage of blankets, covers, and netting will allow for multiple seasons of use. We recommend drying out and folding all coverings before storing them at the end of the season.
Written by Titus Boucher, Locavore Market & Bootstrap Farmer
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