An Introduction to Floating Row Cover

Organic growers have always had to create innovative, safe and effective ways of dealing with the many negative pressures that can affect plants. Unlike conventional farm models, organic growers choose not to utilize broad-reaching and destructive applications like synthetic pesticides, herbicides, and fertilizers to help their plants avoid pests and disease. But no farm field is without these pressures, so organic production models have conceptualized alternative cultural, biological, and physical methods of dealing with those negative forces.

One of these methods is something every modern organic grower utilizes: a lightweight, woven fabric known as row cover (sometimes called floating row cover, reemay, or by the largest industry manufacturer’s trademarked name, Agribon®). This handy, non-toxic fabric acts as an effective physical barrier to plant pests and can extend the harvest season in cool early and late season temperatures. Its benefits include helping to raise the temperature of the covered area by 2-3 degrees Fahrenheit, letting moisture and sunlight in while keeping pesky bugs and dust out, and even protecting against some wind damage.

But . . . it’s also a huge pain in the neck.

What are the downsides? Its lightweight design rips easily, which means many farmers only get one season of use out of a section of row cover before it is no longer an effective barrier. Its weight also makes it nearly impossible to manage by a single person if there is any wind when applying or reapplying it. If left in a field for an extended amount of time - as is sometimes necessary - it can collect soil and water and become highly unmanageable. Plus, while it does an excellent job of protecting the plants you want to grow, it also shields the weed seed in the same areas it covers. If a section of field is left covered for too long, uncovering it may reveal that weeds have taken over the majority of the bed space.

To avoid the common pitfalls of row cover and effectively utilize it as a farm tool, read on and discover the best applications and practices in an organic production model.

Applications

For pest control. Row cover is a successful physical barrier against most pests if used correctly. However, it is important to note that row cover can only be effective insofar as the pests you are attempting to block are not already present in the soil where your plants will be growing. Many common culprits like flea beetles, cucumber beetles and bean beetles overwinter in field edges, not in the soil, so applying a layer of row cover to transplants immediately upon planting is usually successful in keeping these pests away. But certain pests like cutworms, which tend to attack the brassica family, and squash vine borers, which target cucurbits, have larvae that overwinter in soil. If you plant a susceptible crop type into soil in which these pests are already present, row cover will not be an effective method of keeping them from doing damage.

For the most effective physical barrier to traveling pests, place strips of row cover over the crop you wish to protect immediately upon seeding or transplanting. To ensure that pests are kept out entirely, you must secure the edges for the entire length of the strip with rocks, soil, sandbags, or some other weight. Many farmers find it most efficient to “bead” the edges with soil to simultaneously weigh the row cover down and keep pests at bay. You may be surprised at how the tiniest opening can allow outside pests to wreak havoc on your covered plants, so be vigilant in your beading! For plantings of crops with tender greens like arugula, mustards and radishes, the row cover can be removed for ease of harvest and reapplied after harvest, but the edges must be still be wholly secured afterwards to ensure that pests are kept out.

Reemay is applied to a direct-seeded corn crop on the High Mowing seed production farm.

On High Mowing’s production farm, we also utilize row cover for our direct-seeded corn crops to keep away a slightly larger pest: crows. Once corn germinates and their tender little greens emerge, it’s awfully tempting for crows and sometimes even turkeys to make their way into the field and pluck out the sprouted seeds. For a longer season crop like corn, it is necessary to remove the cover periodically to cultivate between the rows. Our production farm team has a rotating schedule for row cover removal and cultivation to be most time-efficient. For a quicker maturing crop like greens or radishes, you may be able to get away with not removing the cover at all until you harvest, as long as you’ve seeded into a clean bed (this is usually achieved by either solarizing the soil or flame-weeding).

For season extension. You can choose to utilize different weights of row cover, from light to medium to heavy. Agribon® includes numbers for each of their fabrics; the higher the number, the heavier the weave. AG 19 is commonly used as a general-use weight for both pest control and temperature moderation in the spring and the fall. In the case of more extreme season extension, you may want to consider a heavier fabric in order to be most effective. Your choice of fabric will depend on your crop goals, crop type, budget and regional climate. Just keep in mind that the flip side of heavier fabric is that less water and light gets through to the plants. Most commercial organic farmers use a lighter-weight row cover that lets in 80-90% light, like AG 15, in the height of the season. Heavier models will let in only 60% light, but will also keep the cold at bay longer.

No matter the weight of the fabric you use, your row cover will create a micro-climate that is often several degrees warmer than the ambient temperature outside. In the spring, this makes row cover a useful tool for covering tender transplants that could otherwise be shocked by cool spring temperatures. Common crops that farmers cover to give them a temperature boost in the spring include cucumbers, squash, zucchini, peppers, and eggplant.

Floating row cover on peppers helps encourage growth by maintaining the warm temperatures they love.

In the fall, row cover can extend the season in the opposite direction, and even helps plants survive the first frosts and snowfalls, depending on the crop. Farmers looking to squeeze every last harvest out of their tomatoes and peppers will often cover them if there is a threat of frost. It is most effective when used to cover cold-hardy greens like spinach, and is often combined with some other type of protection like an unheated greenhouse or hoophouse, or double layers of row cover, to harvest greens into the winter. One benefit of growing these fall crops under cover, unlike spring and summer crops, is that they will get the added temperature boost they need to stay alive, but the annual weed seed that would normally germinate will not have the vigor to withstand the cool temperatures, making your beds essentially weed-free if you give them a good run-through just before covering.

Don’t forget the pollinators! If you’re using row cover on a crop type that requires insects for pollination you have to take the pollinator’s habits into account when you cover and uncover the crop. If the pollinators can’t get in, you’ll have a heck of a time getting any fruit off the plants. To determine when to uncover plants that require pollination like summer squash and zucchini, check under the floating row cover every few days to determine if the plant is going to flower soon. When flowers start to develop, remove the cover so that pollinators can do their thing. Usually, the plants are robust enough at that growth stage that they will be better able to withstand pest pressure and have gotten the temperature boost they need to start producing fruit. Or, to avoid the headache altogether, select parthenocarpic varieties that don’t require pollination to produce fruit: Saber F1 cucumber, H-19 Little Leaf cucumber and Segev F1 summer squash are some of our favorites.

Best Practices

Handling row cover. Any experienced farmer will tell you that no matter how careful you think you’re being when applying a new sheet of row cover, rips are inevitable. However, handling with care and communicating correctly with your partner or partners who may be applying the row cover with you will help to improve the lifespan of row cover. Many farmers also choose to use thin-gauge smooth galvanized wires or PVC pipe cut into half circles to keep row cover up off the ground and above the plants so as not weigh them down as they grow. Wires can be placed every 10 feet or so in the bed, and the smooth surface helps keep the cover firmly in place so as to avoid getting caught on sharp surfaces like rocks, harvest bins, and hoes.

Storing and re-using row cover. Every farmer has their own method for storing row cover, and at a certain scale some even choose not to store and re-use their material because it simply gets too messy and torn to be effective in more than one season. The most common problem for storage is, of course, finding the appropriate space. The space must be both large enough to fit the required amount of row cover, and simultaneously secure from any animals – usually small rodents like moles, voles, rats, and mice – who are looking for a cozy place to hunker down for the cold winter months. An infestation of one of these communities could render your row cover useless because of chew holes, and equate to wasted time and money for your farm as a business.

The High Mowing seed production farm uses a farm hack design to assist with re-rolling large sections of row cover.

If you choose to store your row cover in a barn or other unsealed structure like a tool shed or three-season room, consider storing it several feet off the ground (i.e. in rafter space or on wall-mounted tool hangers). This will make it more difficult if not impossible for rodents to reach, and will simultaneously help avoid any accidental moisture that might gather if the storage area is not perfectly weatherized.

There are several techniques for gathering row cover: rolling is perhaps the most common, either on an appropriately sized piece of PVC pipe (a favored method because it can easily be mechanized and rolled by tractor) or simply rolled into a ball like a giant piece of yarn. For pieces that are wider than 60” it can be easiest to fold them like a bedsheet. There is also a manual technique that can be used for shorter stretches (200’ or less) and only requires one person: “the weave” involves wrapping the row cover in a figure-8 weave around your arms. It can then be slid off onto wall-mounted tool hangers or simply onto a flat surface. When executed correctly, the weave unravels with ease and avoids tangling the row cover unnecessarily or ripping the edges, as is risked when rolling onto a PVC pipe.

No matter which method you choose to collect and store your row cover, one simple practice will save you lots of headache in the spring when you’re getting it out again: labeling. Making note of the lengths, widths and peculiarities of the pieces you choose to save will increase your efficiency when you’re applying used row cover the following season. The most efficient systems usually standardize the lengths and widths of their cover; that way the only notes that have to be made about particular pieces are what condition they are in and whether they have a few holes, a lot of holes, or hardly any holes.

Photo courtesy of Footprint Farm.

Taylor and Jake Mendell of Footprint Farm in Starksboro, VT shared their very effective method on their Instagram page (@footprintfarm) this spring: "This one's for everyone who thinks organization is sexy. It took us approximately 2 minutes to find the right length, width, and quality row cover today, which is pretty much my favorite feeling," wrote Taylor. "Thank you to the IG account who let us in on this magic system years ago. If I remembered who you were I'd give you a serious virtual fist bump. These covers are stuffed into potting soil bags, and we label them with S/D/T (single/double/triple bed coverage), A/B/C for quality (A is good enough for flea beetles, B is anything else that is still super usable, C is on its last leg), and the length bed that it was cut for. Then we hang or stack the bags in our tool shed until ready to use."

Although the downsides may seem numerous, there are plenty of reasons floating row cover continues to be used in organic production systems on every scale. The satisfaction of peeking under a section of row cover in the early spring to find lush, tender greens growing beautifully, or knowing that your plants are cozy and protected under a double-layer of row cover when the first hard frost hits in the fall makes it completely worth all the hard work.

Tell us about your tricks for handling row cover and how you choose to use it in the comments section below!