How can we protect our crops while enhancing other properties of the soil-air interface?
Background: Using Row Cover
When gardeners lack natural buffers (regulating agents) to protect their growing operations, the use of simple row covers can provide numerous benefits for cultivated plants against a variety of threats. In the context of a rapidly changing climate, these threats, like extreme weather events and pest outbreaks, have become more numerous, while afflicting higher magnitudes of damage on ecosystems and human landscapes. Therefore, even robust gardens with effective biological defenses in place have found row covers to be useful in the era of anthropogenic global warming.
Row covers are fabrics that are overlain on germinating seeds, seedlings, and mature plants, as well as terminated cover crops, compost applications, and other mulches. They aid in early stages of plant growth, provide protection from temperature shocks, deter pests, and retain moisture in the soil and ground-level air. They are semi-permeable by design, allowing water, light, and air to pass through to the surface below. While they are relatively easy to set up, it is important to be mindful of when row covers are applied if they are to be effective safeguards against disaster.
Students will be able to...
Erect row covers on garden beds while accounting for timely considerations
Understand the benefits of row covers
anthropogenic /ˌanTHrəpōˈjenik/ adjective. - deriving from or relating to humans
buffer /ˈbəfərl/ noun. - a mechanism for preventing drastic or definitive action or movement
permeable /ˈpərmēəb(ə)l/ adjective. - a characteristic of a surface or material that allows certain substances to pass through, while keeping other substances out
1. Gather your materials. You will need the following supplies:
row cover (cut to a length to fit your garden bed or crop rows) · heavy objects (rocks, bricks, pallets, fence posts, etc.)
2. Watch the following YouTube video to see a demonstration of how to use row cover. Then, follow along with the remainder of the lesson by reading the steps below.
3. Before applying row cover to a garden bed, it is important to understand the different roles that row cover plays at different times of the season:
🕒 Timing is everything… The function of row cover varies with seasonality, by the age of the plants that it serves, and even by the time of day: to allow for the most sunlight to reach certain plants, and for pollinators to find flowers to inspect, it is sometimes necessary to remove row cover if only for a few hours at once. Listed below are the variables that row cover helps control:
Temperature: During warm days, white row cover can reflect sunlight to keep the surface of the soil cool. On the other hand, it can insulate crops from frost to extend both the spring and fall growing seasons. The additional warmth can also help seeds germinate.
Moisture: Row cover will help retain water from leaving the ecosystem by shielding from winds that sweep the moisture away. They are also effective at protecting against heavy rains and hail that would otherwise lead to excess water buildup, soil compaction, and crop dieback.
Pests: A row cover applied to a garden bed before pests arrive is able to hide crops from the sight of insects and birds, and provide a physical barrier for any unwanted creatures that do happen to arrive. Be careful, though -- applying a row cover after harmful insects have arrived may create a wonderful environment for them to breed! Place the row cover on seeds once they are planted to prevent this unintended consequence.
Other factors: Row covers can provide shade for crops that prefer less light, which can prevent them from going to seed too quickly. It is also effective for helping breakdown green manures from cover crop residue.
4. After considering the specific need that the row cover will provide and the appropriate time constraints under which it should be applied, it is time to spread it over the garden bed:
a. A “floating” cover can be used at the surface of a bed that contains germinating seeds, young seedlings, or compost/green manure. Simply fit a piece of fabric to the size of the bed by overlaying it on the surface, then folding the edges towards the center (or cutting it) to a slightly larger but squarely fit piece. Weigh the fabric down with rocks, bricks, posts, or other heavy objects to secure the fabric from blowing away (avoid setting weights down on living plants).
b. A “supported” cover can be used in conjunction with supplemental equipment such as hoops, stakes, and clothespins. Before applying a supported cover, use metal hoops or stakes to create a structure for a piece of fabric to be overlain. The hoops or stakes should be spaced at a distance where the fabric will not become droopy so as to touch the crops beneath -- every couple of feet, depending on the spacing of the crops. The height of the structure should be at least a few inches above the tallest plant. Cut or fold a piece of row cover to fit the structure and garden bed, and place it over the top. Use clothespins to secure the cloth to the frame, or simply weigh the fabric down with bricks or rocks.
Download the PDF version of this lesson plan: