How to Use Floating Row Covers for Temperature and Pest Control
Floating row covers can be used to maintain consistent temperatures, reduce pest pressures, and so much more. In this expert guide, Sarah Jay explains their many uses and how to make the most of row covers in your garden.
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One summer, I came out to my back garden to find all my basil seedlings gone. I didn’t know what could have taken them out and assumed it was insects. Later that week, I discovered the culprit was a cardinal. If only I had used floating row covers to protect my basil seedlings, I’d be stocked up on pesto right now.
While floating row covers are great for protecting plants from birds, they also serve as a useful barrier between plants and insects or other mammals that may want a little snack from your garden. They’re protective in other ways too, shielding fully grown plants and seedlings alike.
If you’re considering garden row covers, remember there are many different types to choose from, made of different materials. You can fashion them for raised beds or simply use them to cover plants growing in garden beds in the ground. They’re useful for both cool-season and warm-season crops.
So let’s talk about floating row covers, examine the different types, and discuss how you can set up your own at home.
What Is a Floating Row Cover?
Floating row covers are long pieces of fabric made of woven plastic, polypropylene, natural fiber, plastic, or polyester materials. They may be affixed directly to the earth or laid over a structure that keeps them off the surface of plants. Using row covers can bring many benefits to the garden.
My basil, for instance, could have used a little protection from the cardinal plucking seedlings out to snack on. Some row covers are light enough that plants can still absorb moisture and light while they’re protected. All row covers create a barrier between plants and some external force that could damage them.
How Floating Row Covers Work
Row covers have multiple functions that can occur at the same time. As you read through their uses, consider what your garden plants need. This will help you determine what kind of garden row covers are best for your home garden.
Pest Management
Birds, insects, and mammals love to dig up, pluck out, or feast on seedlings and some fully grown plants. Row covers keep out many pests in the home garden. With a row cover as an insect barrier, your seedlings get a good head start. Established garden plants that typically deal with a lot of pests in a season also benefit from row covers, which put a wall between them and common threats.
A floating row cover is especially useful for protecting warm-season crops, which grow when insects are most active. This also applies to cool-season crops that grow across cool and warm seasons.
If you’re using crop rotation to keep pests at bay, use row covers to trap them in an old bed while you protect the new and exposed bed. This works well for insects that overwinter in garden soil or lay eggs that remain in the soil through winter, waiting to emerge in spring.
If you want to trap and destroy pests within the covered rows, plant flowers like marigolds or calendula that they’ll be attracted to. Then place a support and polypropylene row cover over the garden where they’ve been trapped. As they feed, they’ll be unable to seek out the flowers of tomatoes or other vegetables. Once trapped, remove the row covers and destroy the trap crop.
Plant Protection
Just as young seedlings need protection from insects, row covers are also great for wind and frost protection. They can provide shade for young plants and plants that are particularly sensitive to direct light. Row covers help new plants develop strong roots by preventing snapping in the wind. They also provide frost protection for plants that need to be planted in early spring but are sensitive to cold.
Row covers act as a kind of shade cloth for garden plants, helping maintain moisture levels on warm days when a normal irrigation schedule won’t cut it. They’re also great when temperatures drop, keeping the soil warm below.
If you struggle with both insect or herbivore damage and want to protect your plants from frost, a simple critter cage topped with a critter cover frost blanket is an easy solution. The blanket works like a row cover but fits securely over the cage to provide insulation from cold and block out any creatures that like to munch on your plants.
Row Covers as a Season Extender
Aside from plant protection and pest exclusion, row covers are a great solution if you want to extend the growing season. While they provide frost protection, they also ensure cool-season crops can keep growing in warm weather without bolting. Cool-season vegetables like broccoli and leafy greens are especially sensitive to heat, and a floating row cover will prevent the premature flowering that occurs on many garden plants.
Row covers also allow growers to plant crops about one to two weeks early, extending the season on the front end rather than the back end.
Floating Row Cover Types
There are three basic types of row covers: heavyweight, mediumweight, and lightweight. The season you’re working in can also influence which row covers you choose. Consider the following when determining which type of cover to use.
Lightweight Covers
A lightweight row cover doesn’t require support for adequate plant growth, but it can work just as well in a hoop system. Lightweight covers are permeable, allowing precipitation and sunlight to come through.
They aren’t great for protecting plants from frost because they can’t trap much heat for temperature control. They do, however, serve as a decent shade cloth for light-sensitive plants.
Mediumweight Covers
Mediumweight covers are best for extending the season in spring and fall, as they trap warmth more effectively than lightweight covers. They also shield plants from elements that may dampen yields. Root crops especially benefit from a mediumweight cover.
Two layers can do more than just one if you’re working in a particularly cold winter. This type of cover is also permeable to light and water.
Heavyweight Covers
Heavyweight covers are the best option if you need to protect plants and crops in an extended hard freeze, much like a frost blanket. They trap warmth in a garden row when frost causes temperature dips between 4 and 8°F (-15 to -13°C). Note that a heavyweight cover provides a lot of protection for the soil and the plants growing there, and can increase temperatures quite a bit in direct sunlight.
For this reason, you should remove this fabric cover from your row crops when the sun rises. Too much heat can cause blossom drop on certain spring and fall plants. Tomato crops, for instance, can suffer blossom and fruit drop at 86°F (30°C) and above under a heavyweight material.
Unsuspecting Row Covers
If you don’t have polypropylene or polyester fabric and supports lying around, there are other options. Use items you have at home, like greenhouse plastic, old sheets, a tarp, or old towels and blankets. In the cold seasons, sow your crops under large plastic bins that have small air holes.
You can provide support in the form of wooden stakes, sturdy branches, or dowel rods, though supports aren’t necessary. Remember that you will need to remove plastics as soon as the sun rises so the plants within don’t cook. The other covers listed here should also be removed from direct sun, but they won’t trap as much heat as plastic.
How to Set Up a Floating Row Cover
Determine which crops in your garden will benefit from covers, then purchase the appropriate materials. Remember that row covers used as shade cloth should be a lightweight garden fabric.
A row cover used to trap heat and help fall season crops survive multiple seasons should be a thicker medium or heavyweight garden fabric. Some brands focus on one thickness, while others offer a wider array of row covers to choose from.
You can lay your floating row cover directly on the ground and affix the edges with stakes, fabric staples, or heavy bricks or stones. Alternatively, you can set them up over PVC piping, in low tunnels, or over a larger frame or support structure. If you’re using row cover to protect fruit trees from intense sunlight, temperature fluctuations, or bugs, drape it over the tree and tie it at the trunk.
Building Hoops
If you want hoops over your gardens, purchase material to create them so the fabric cover can sit above the row. Bendable wooden sticks or branches work well for this purpose. PVC piping is also an excellent choice and will hold up longer over time.
When using PVC, you will need rebar posts or strong rods that can fit within the piping about eight inches above the ground. They should also be long enough to be driven deep into the garden soil next to your row crop. Space them a couple of feet apart on each row, and across from one another on either side.
After you drive the rods in, ensure they’re secure and then place the PVC piping over them. Ten feet of piping creates large hoops over the crop that allow for good air circulation while also trapping warmth if needed. There’s room to try different lengths of piping if 10 feet is too much. Then drape your garden crop cover over the hoops and secure it to the piping with PVC clips.
Pull the rest of the fabric cover tightly and secure the base edges to the perimeter of the garden bed with heavy objects or landscaping fabric staples. Draping the fabric works best with multiple people. When you remove the piping, place something brightly colored over the rods to ensure no one gets hurt in the garden.
Premade Options
If developing your own row covers isn’t appealing, there are plenty of premade options. If you’re growing vegetables in raised beds, consider a raised bed frost cover, which includes a frame that sits over the edges of the beds. Cover single plants with pop-up crop protectors.
Alternatively, consider a planket, which is great for container-grown plants like tomatoes, small trees, and shrubs. This cover is made of non-woven material and has a cinch cord at the bottom so you can drape it over trees in an orchard row and tie them at the base. Plankets work best for covering plants in cold weather.
Finally, you can buy a frame that acts as a support for a row cover, allowing you to drape polypropylene or some other woven material fabric over your plants.
Row Cover Maintenance
Premade options are great, but every row cover requires maintenance. Because row cover material can trap heat in direct sunlight, it protects plants but does not block out weeds. You’ll need to remove your row cover occasionally to pull weeds underneath.
Another thing to consider is repairing row cover material after a few seasons of use. Unless it is a heavyweight material, it will degrade over time in direct sunlight and the elements. Supports may also need replacing after a few years. Take some time each season to check your covers and ensure they have the structural integrity you need to protect your plants.
Frequently Asked Questions
Do floating row covers work?
It depends on what you need them to do, and what type you purchase for that purpose. If you need them as a frost cover, use something medium weight. If you need them to shade plants, use something lightweight. See above for more types and uses!
What can I use instead of a row cover?
You can use old towels, blankets, a tarp, greenhouse plastic, a plastic tub, or old sheets.
Are row covers worth it?
They certainly are. Because they provide multiple forms of protection at once, look into how to secure your own!
How much earlier can you plant with a row cover?
Certain crops can be planted a week or two early.
Can I leave plants covered all day?
It depends on the season and the type of cover you’re using. In an arctic winter, you likely can leave any cover on. In snap freezes, remove heavier covers as soon as the sun rises.
