There are lots of things to protect your plants from: cold, pests, wind, and so forth. Row covers can protect your plants against some of these hazards if you use them correctly.
So, what are row covers? A row cover is a sheet of lightweight, flexible fabric that is used to protect plants from cold, wind, and pests. Thicker row covers are heavier but provide more protection. Row covers are typically made from polyethylene, polyester, or polypropylene.
Of course, it is also helpful to know what types of row covers to use and how to use them.
In this article, we’ll talk about what row covers are, what they are made of, and what they are used for. We’ll also provide some details about how to use them in your garden to protect your plants.
What Are Row Covers?
A row cover is made of a lightweight, flexible fabric. It is used to protect a row of plants from cold, wind, and pests.
It is sometimes called a “floating” row cover when it is supported by the crop you are covering. Of course, you can also use supports to secure a row cover well above plants so that they are not touching the cover.
Row covers are somewhat transparent, and they allow varying amounts of air, water, and sunlight through while keeping pests away. As a result, your plants can continue to grow without the damage and diseases brought by pests.
Row covers also help to extend your growing season in both the spring and fall, since you can protect plants against frost.
The temperature and humidity underneath a row cover will be higher than the rest of your garden. As such, a row cover can help to speed up seed germination (or it can allow you to sow seeds sooner).
Although row covers are useful, you will need to remove them temporarily during the growing season if:
- you want to fertilize your plants
- you want to allow bees and other pollinators to get to your plants
- you want to get a closer look at your plants to gauge their progress
- temperatures get too high and your plants need to cool down
What Are Row Covers Made Of?
- Polyethylene – this plastic material can be clear, or it can have color if pigment is added. Generally, polyethylene builds more heat than other materials (and clear plastic builds heat more than colored plastic). As such, polyethylene row covers may need to be vented in some cases so that plants underneath it can breathe.
- Polyester – this fabric material is spunbonded (not woven), and is treated with heat and pressure during the production process. It doesn’t normally need venting, since the material “breathes” on its own.
- Polypropylene – this fabric material is spunbonded (not woven), and is treated with heat and pressure during the production process. It doesn’t normally need venting, since the material “breathes” on its own.
Some brands of row covers include:
You can reuse row covers, but they will eventually break down and you will need to replace them.
Row covers vary in their thickness (density or heaviness). The thickness of a row cover determines how much cold protection it provides and how much light it lets through.
Row covers are divided into two main classes: lightweight and heavyweight. Let’s start with lightweight row covers.
Lightweight Row Covers
Lightweight row covers are sometimes called insect barriers or summerweight garden fabric. They have the following properties:
- Sunlight penetration: 85% to 95% of sunlight gets through
- Frost protection: 2 to 6 degrees Fahrenheit of cold protection
- Pest protection: keep insect and animal pests away from crops
- Weight: around 0.5 ounces per square yard
Lightweight row covers will not warm up crops as much as heavier row covers would. As such, lightweight row covers are ideal for heat-sensitive crops, such as lettuce, spinach, and other cool-weather favorites.
Here are a couple of lightweight row covers you can try:
- Agribon+ AG-15 – this Agribon-15 row cover from Johnny’s Selected Seeds has 90% light transmission and weighs just 0.45 ounces per square yard. You can learn more about Agribon+ AG-15 row covers on the Johnny’s Selected Seeds website.
- Agribon+ AG-19 – this Agribon-19 row cover from Johnny’s Selected Seeds has 85% light transmission and weighs just 0.55 ounces per square yard. You can learn more about Agribon+ AG-19 row covers on the Johnny’s Selected Seeds website.
Heavyweight Row Covers
Heavyweight row covers are thicker than lightweight row covers, and as a result they are 3 to 4 times heavier. They have the following properties:
- Sunlight penetration: 50% to 70% of sunlight gets through
- Frost protection: 4 to 10 degrees Fahrenheit of cold protection
- Pest protection: keep insect and animal pests away from crops
- Weight: about 1 to 2 ounces per square yard
Heavyweight row covers will warm plants substantially. As such, they are ideal for heat-tolerant crops (such as tomatoes and peppers) that need protection from spring and fall frost.
Here are a few heavyweight row covers you can try:
- Agribon+ AG-30 – this Agribon-30 row cover from Johnny’s Selected Seeds has 70% light transmission and weighs 0.9 ounces per square yard. You can learn more about Agribon+ AG-30 row covers on the Johnny’s Selected Seeds website.
- Agribon+ AG-50 – this Agribon-50 row cover from Johnny’s Selected Seeds has 50% light transmission and weighs 1.5 ounces per square yard. You can learn more about Agribon+ AG-50 row covers on the Johnny’s Selected Seeds website.
- Agribon+ AG-70 – this Agribon-70 row cover from Johnny’s Selected Seeds has 30% light transmission and weighs 2.0 ounces per square yard. You can learn more about Agribon+ AG-70 row covers on the Johnny’s Selected Seeds website.
Do Row Covers Work?
Row covers work to protect plants against pests, cold, and wind. However, they will be most effective if used properly.
If you want to keep pests away from the plants under a row cover, make sure the row is completely closed off. This means securing the edges and ends of the row cover (more on this later).
(If you have a problem with aphids, check out my article on how to get rid of them).
Lightweight row covers offer limited cold protection, so choose thicker heavyweight row covers to provide more frost protection. Just remember that heavyweight row covers are more expensive than lightweight row covers.
Row covers will not protect against a strong wind or storm, so be sure to use other methods if necessary. You can learn more about how to protect plants from wind in my article here.
Do Row Covers Protect From Frost?
Row covers do protect plants from frost, and they can provide 2 to 10 degrees Fahrenheit (1 to 6 degrees Celsius) of cold protection. The extent of frost protection depends on the density or thickness of the row cover.
However, row covers are much better at warming up plants than at protecting against frost. According to the Michigan State University Extension:
“When using row covers always keep in mind that they are more efficient at increasing temperature especially during a sunny day than at protecting against frost.”https://www.canr.msu.edu/news/row_covers_for_frost_protection_and_earliness_in_vegetable_production
Even if you use row covers, extreme cold could end the season for your plants. It is possible that a cloudy day with no sunlight followed by a night with subfreezing temperatures will be too much for tomatoes, peppers, and other frost-sensitive plants to survive.
Remember that you may need to temporarily remove row covers if the weather gets too hot. This is especially true for plants that prefer cooler temperatures.
Do Row Covers Provide Shade?
Row covers do provide some shade for your plants. The amount of shade depends on the thickness of the row cover material.
Lightweight row covers can allow as much as 95% of sunlight through. On the other hand, heavyweight row covers might allow 50% or less of sunlight through.
Just remember that plants need to get enough sunlight to grow, and some will not tolerate being covered all day for extended periods.
Plants whose fruit is susceptible to sunscald (such as tomatoes) may do better with row covers to protect them from intense sunlight. However, if strong sunlight is a concern, then shade cloth might be a better choice for you.
Shade cloth filters sunlight and protects plants from heat. Some shade cloths can reduce the temperature of fruit by up to 20 degrees Fahrenheit!
Shade cloth protection varies quite a bit – some let through only 5% of sunlight, while others allow 95% of sunlight through. You can learn more about shade cloth in my article here.
There are lots of other ways to give shade and protect your plants from summer sun and heat – you can learn more in my article here.
Can You Water Through Row Cover?
You can water plants through a row cover, since they are water permeable. As such, a sprinkler or spray nozzle attachment on a hose will work just fine for watering your plants.
However, you can also set up a drip irrigation system before you put row covers over your plants. Just be sure to let your row covers dry out completely before you store them at the end of the season (this will avoid mold and mildew on them).
Do Tomatoes Need Row Covers?
Tomatoes do not need row covers to survive, but you can certainly use row covers to offer extra protection. For example, cutworms are dangerous to tomato plants early in the season, but they aren’t as much of a threat once tomato plants get larger.
Row covers can also protect tomato plants from late spring frost. This is especially helpful in cold climates with a short growing season.
How To Use Garden Row Covers
To use row covers for plant protection, the first thing to do is to choose the appropriate type of row cover. Refer to the information earlier in this article on lightweight and heavyweight row covers and the grades of each that are available.
In general though:
- Lightweight row covers are best for protecting plants from pests or light frost.
- Heavyweight row covers are best for protecting plants from intense sunlight or hard frost.
Next, you will need to cut it the row cover to the right size. Any pair of scissors that can cut fabric will work to cut row cover material.
Just make sure to leave a little extra material on both the length and width. This will leave some material on the sides and end so that you can secure the row cover.
How To Secure Row Covers
- Soil – this method is basic but free. After your row covers are in place, pile up some soil over the edges on the sides and ends of the row.
- Rocks – this method is also basic and free, just like soil. However, rocks won’t blow away in the wind or wash away in a rainstorm like soil might.
- Boards – there is some cost to this method, unless you have some old wooden boards lying around. Wooden boards provide enough weight to hold down the edges of a row cover, but they are much easier to remove and replace than soil or rocks. The only problem is that they will eventually rot.
- Sod pins – there is some cost to this method, but they are very convenient. Metal sod pins can be reused year after year without worrying about rot. Here are some sod pins (anchoring pins) from Johnny’s Selected Seeds.
If you are gardening on a large scale, you might need to secure lots of row covers. In that case, you can try this set of 250 hand pegs from Johnny’s Selected Seeds.
Johnny’s also has snap clamps, which are used to easily attach row cover material to PVC pipes. This is useful if you are using hoops to suspend row covers above your plants.
Just be sure to get the right size, depending on the thickness of your PVC pipe. Here are snap clamps for ½ inch PVC pipes from Johnny’s Selected Seeds.
Another option for holding up row covers is to use wire hoops, such as these ones from Johnny’s Selected Seeds. They are more flexible and easier to use than PVC pipe.
One other option is to dig a trench, plant inside the trench, and put a row cover over the trench. One advantage is that you won’t need to use PVC pipes or stakes to hold up the row cover material.
One drawback is that you might have to bend over in an uncomfortable position to get to your plants if you need to fertilize, harvest, etc.
When To Remove Row Covers
There are a few situations where you might want to remove row covers. For example, when you want to:
- fertilize your plants (sometimes side-dressing during the season is needed to improve yields)
- pollinate your plants (to allow access for bees, or if you need to hand pollinate in the absence of bees)
- examine your plants (to check for heat stress, drought, diseases, or pests that got past the row cover)
- cool down your plants (when temperatures run high in the summer)
Once these tasks are complete, you can replace the row covers to provide continued protection for your plants. However, if your plants only need frost protection at the beginning of the season, then you can remove row covers after danger of frost has passed.
Where To Buy Floating Row Covers
You can buy floating row covers online from:
You can buy them in person at:
- Home Depot
- Any store with a garden center (hardware stores, Walmart, etc.)
Now you know what row covers are, what they are made of, and what they are used for. You also know how to decide which type is right for you, based on your gardening needs.
You might also want to read about more ways to cover plants in my article here, and when you can leave plants covered all day.
I hope you found this article helpful. If so, please share it with someone who can use the information.