Clear plastic vs fabric row cover: which is better for you?

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Row cover is a great garden and farm tool to protect against cold weather and pest insects, but there are a lot of options to choose from. Clear plastic vs fabric row cover? Lightweight vs heavyweight? In this article, you’ll find out which options are best for you — and how to use them. 

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Article table of contents:

1. What is row cover and what are the benefits?
2. Row covers: three essential material considerations
3. Three tips on effective use of row covers
4. Row cover products

I. Row cover: what it is and why it’s used.

What is row cover?

Row cover is a lightweight synthetic material used to cover plants in gardens and on farms. Row cover is made from either:

1. clear plastic polyethylene sheets (the same material often used on greenhouses and high tunnels), or
2. fabric made from spun-bonded polyester.

For the sake of simplicity, we’ll simply refer to these two materials as either “clear plastic” or “fabric” row cover for the remainder of this article.

How is row cover used?

Row covers are either:

1. laid directly over low-growing plants, or
2. elevated above plants on a supporting frame.

Since it lays atop plants, row cover is also referred to as floating row cover or frost blankets. Row covers elevated above a row crop on a supporting frame are called “low tunnels.”

Why use row cover in your garden or farm? 

Row cover can be used for any of the following reasons:

1. Get an early start on the summer growing season by increasing the temperatures of the air and soil inside.
2. Extend your summer growing season.
3. Grow cool weather crops throughout the fall, winter, and early spring (depending on your climate zone).
4. Keep pest insects off of your plants.
5. Improve seed germination in direct-sown crops.

Are row covers worth it – do they generate a good ROI?

Row covers are widely available, easy to use, and tend to be relatively inexpensive. In fact, if you calculate the total cost of a row cover versus the value of the crops you grow under them, you’ll likely find that they’ll more than pay for themselves after a single growing season.

For many small farms, row cover is a critical technology that allows them to continue operating and generating revenue during seasons when, historically, few if any crops could be grown. It would be interesting to see research on just how much this season extension technology has contributed to increased specialty crop production in the United States over the years.

Is row cover reusable? 

Properly maintained and stored when not in use, row covers are also reusable and can last for years before needing replacement. Product longevity will vary greatly based on product quality, your climate, and usage frequency.

How long will row cover last?

• Clear plastic row cover (polyethylene) can last for 3-5 years before becoming too brittle to use or too “foggy” to allow optimal sunlight transmission;
• Fabric row cover (spunbonded polyester) can last for 3-5 years before becoming too worn to be effective.

II. Three essential row cover material considerations

How do you decide which type of row cover (and which thickness) is best for you based on the plants you’re growing, your climate, and other factors? Here are three factors you’ll need to consider:

Consideration #1: Clear plastic vs. fabric row cover?

There are important differences to consider when choosing between clear plastic and fabric row cover:

a. Price:

Generally speaking, clear plastic row cover is a bit more expensive than fabric row cover. However, what price you pay will vary depending on manufacturer, quantity purchased, and material thickness, so be sure to do a price comparison of the products you’d want to use if cost is the key deciding factor for you.

b. Temperature boost:

Clear plastic row cover traps more heat than fabric row cover, potentially providing up to 8-10 degrees of frost protection, depending on the material thickness. That’s why they’re more popular for gardeners and farmers who live in colder growing regions. Fabric row cover adds anywhere from 2-6 degrees F frost/freeze protection, depending on material thickness. They’re more popular for gardeners and farmers living in warmer/milder regions.  However, on sunny, warm days, the air temperature and soil temperature under clear plastic row cover can get hot fast, causing heat stress to your plants unless you pull back the cover to allow the heat to escape. On a sunny day when high temperatures hit 60°F+ (16°C), clear plastic low tunnels can potentially increase the internal temperature by as much as 30 degrees F. As a general rule when growing cool weather crops, row cover should be pulled back and vented whenever outside temps reach 55°F (13°C) or higher. Yes, this means you’ll have to stay even more tuned to your weather forecast!

c. Air flow: 

There is virtually no air flow underneath clear plastic row cover. Continuous lack of air flow can cause moisture buildup and plant damage/disease under some conditions. Fabric row cover allows more airflow, but that’s also why it doesn’t perform as well at keeping temperatures warmer.

d. Rain/snow: 

Fabric row cover allows rain in, thus watering your crops. Clear plastic does not allow water penetration.  Snow can be tricky with either material… It will build up on the top of fabric row cover causing the material to stretch and droop, potentially putting a lot of weight on top of your plants. Snow can do the same thing on top of clear plastic, but if you have a good frame/support system underneath, the snow can slide off as it accumulates, or easily be shaken or pulled off by hand.

e. Microplastic shedding: 

We often wonder how much microplastics are being shed from fabric row cover on to the plants and soil below. This is not an issue that most people are aware of, but it may be in the near future as more research information comes to light.  In soil, these microplastics can accumulate and cause all sorts of problems. To what degree row cover microplastics can be rinsed off prior to human consumption is going to vary by plant type. For example, broccoli florets are likely to trap more microplastic particles than a smooth, round kohlrabi.   Our guess is that clear plastic sheets are far less likely to shed microplastics than fabric row cover. Again, this is not currently a top-of-mind issue that most consumers and farmers consider, but it could be in the near future.

f. Pest control: 

Clear plastic and fiber row covers provide equivalent degrees of pest control.

Consideration #2: Material weight 

You can choose lightweight, medium weight, or heavyweight row covers depending on your needs. The product should detail the precise level of frost protection and sunlight transmission. According to Michigan State University Extension, lighter weight clear plastic and fabric row cover provide cold protection only to about 28°F. However, heavier covers may protect plants when temps drop as low as 20°F. Quick summary of pros and cons of various weights: Benefits of light-medium weight row cover:

• Lets in more light relative to heavier weight cover.
• Can be left in place longer and through higher temperatures than heavier covers.
• Less expensive than heavier covers.
• Lighter weight fabrics allow better airflow than heavier fabric (doesn’t matter with clear plastic).

Cons of lighter weight row cover:

• Doesn’t trap as much heat.
• More likely to be damaged by high winds, deer hooves, boots, tools, etc.
• Will likely have to be replaced sooner than heavier weight covers.

What is summer weight row cover and how is it used?

Extremely lightweight row cover made of poly fabric (aka summer weight row cover) doesn’t provide as much in the way of frost protection. However, it can be useful for animal and insect protection during the warm seasons. It can also be used as shade cloth to reduce plant heat stress or sun scald.  Summer weight fabric has to be removed for insect-pollinated crops while they’re in bloom — unless you’re hand-pollinating them yourself in a garden. A similar option used in the summer is insect netting, which is lighter and more porous than summer weight row cover. Both these options are a good way to prevent crop damage from some of the most dreaded pests: deer, squash vine borers, squash bugs, and cucumber beetles.

Consideration #3: Row cover supports & weights 

Should you provide support for your row cover or not? If so, what’s the best material? Ideal height and spacing? What’s the best way to hold your row cover in place? Let’s discuss:

a. Row cover supports or not?

You could lay your row cover right on top of certain low-growing plants like spinach and similar leafy greens. Having a lower profile might even help prevent strong winds from ripping the row cover off.  Downsides of going frameless?

• It’s not feasible for taller, more upright plants.
• You put extra weight/pressure on plant leaves which could cause damage or undesired shape, especially during periods of snow or heavy rain.
• There’s no “air cushion” between inside and outside. In fact, leaves of tender plants that make direct contact with clear plastic row cover on sub-freezing nights will get frostburn.

For these reasons, almost without exception, we use frames to support our row cover.

b. What’s the best material for row cover supports?

Over the years, we’ve used PVC hoops and metal hoops for row cover support.  PVC frames only lasts a couple of years before becoming brittle and unusable. That’s not a great ROI and it creates pollution and garbage.   Galvanized steel hoops/frames last virtually forever and are very easy to install and use. These are what we use and recommend for your low tunnel supports. You’ll want 10 gauge steel or perhaps a little higher in areas where snow is common. Money saving tip: You can buy large amounts of uncut 10 gauge steel wire from Lowes or Home Depot and cut it yourself rather than buying pre-cut wire.

c. Best size and spacing of low tunnel hoops?

• At the center point, your low tunnel hoops should be 16-18” high.
• For a standard 30″ bed, that means individual wire lengths need to be somewhere between 60″ – 76″ long (we prefer the longer end of that spectrum to deeply anchor the ends for better support).
• Low tunnel hoops should be spaced 5’ to 8’ apart.

d. How do you anchor your row cover? 

First, what not to do: Don’t use pins, spikes, or anything overly abrasive to anchor the ends and edges of the cover. That’s because you want to do everything possible NOT to ever rip your row covers.  For home gardeners on a tight budget, using anything from cobblestones to logs to re-filled up-cycled water bottles can be a good idea to anchor your row cover. Professional market farmers we know invariably use “row bags” to weight down their row covers. These bags are purchased empty, then filled with sand, soil, or rocks by the farmer.    Row bags are:

• inexpensive,
• last a long time, and
• provide a uniform size and weight across the surface of the row cover edges.

Row bags should be spaced across from each other, roughly equivalent to the hoops, about 5′ – 8′ apart. If your row cover is getting blown off, add more row bags spaced closer together.

III. 3 tips on effective use of row covers

1. Secure the edges and ends. 

As detailed earlier, row covers need to be secured along the edges and ends with heavy objects: row bags, cobblestones, etc. Otherwise, the cover will blow up and potentially entirely off during heavy winds, leaving the plants below exposed.

It bears repeating: do NOT use anything sharp that will tear your fabric or you’ll drastically shorten the useful life of your row cover. In fact, the rocks in the picture above are probably a little rougher than they should be. Smooth cobblestones or row bags would be better.

2. Watch for pest insects inside your low tunnels.

Keep in mind that any pest insects (such as aphids) that happen to make it into the warm, protective environment under your row cover may multiply quickly, since predators aren’t able to get in to control their populations. (This is less of a problem in winter when pests are less active or dormant.) Be sure to regularly check for pest insect proliferation under your row covers. You may need to use neem oil or similar products for organic pest control if so.

3. Consider pollinators.

One thing to consider is that a secure row cover effectively keeps out the pest insects, but also blocks bees and other pollinators. If you’re growing plants that require insect pollination (example: watermelons), row covers may not be the best option for pest control.  If you do opt to use row cover on insect pollinated crops, the cover must be removed when plants are blooming. Or if you aren’t ready to remove the cover entirely, open the ends or roll up the sides during the morning, when pollinators are most active.

IV. Row cover products

Ready to start using row cover? Hopefully, you now know what type of row cover is best for your garden or small farm and are ready to get started.  Here are some quick links to help you find the best-rated low tunnel products to meet your needs:

• clear plastic row cover
• fabric row cover
• low tunnel frames (if you don’t want to cut your own from 10 gauge wire)
• sandbags for anchors

Happy gardening!

Other cool season garden & farm articles you’ll want to read:

• DIY cold frames: how, why, and when to use
• Best cold weather garden plants
• Easy and affordable DIY grow light system
• Fall and winter succession planting for continual garden harvests
• How to grow Austrian winter peas for the best pea greens ever
• Organic pest control for kale and other brassica crops
• Late winter and early spring garden transition tips