Extend the Growing Season By Using Frost Blankets for Plants

It is supposed to get cold tonight, cold enough to freeze, and I still have a lot of plants in my garden! What can be done when the approaching winter brings low temperatures, and my plants need protection?

Many people have asked how I am preparing for a frost and if I use any kind of frost cover. I have been using frost blankets for about 3 years now, and let me tell you, they are a gardening tool that I would not want to live without!

In this blog post, I will answer all your questions about using frost blankets for plants, the best frost cover fabric, and how this DIY approach can protect spring and fall garden plants to extend your growing season.

Cold Weather Gardening

Every innovation started with a roadblock! Even though cold, unpredictable weather makes gardening in winter, fall, and spring tricky, there are some great innovations out there that can help you extend the growing season.

• Gardening in the Winter: Methods for Growing in Cold Weather
  

• Building a DIY Cold Frame

• Winter Sowing in Milk Jug “Cloches”

• Greenhouse Gardening: What You Need to Know

• How to Heat a Greenhouse

What Are Frost Covers

Frost blankets are row covers specifically designed to protect plants from damaging frost and cold winds. The lightweight fabric can provide 5°-10°F of freeze protection, sometimes more (depending on the fabric density and ambient humidity).

They are the real deal. The image below shows my nasturtiums after one night of near freezing temperatures, one half was covered with a frost blanket and the other half was not. 

Long gone are the days of using old bed sheets to try to protect my plants. Frost blankets have undeniably saved our crops!

Benefits of Using Frost Blankets for Plants

Some people would advocate using a low tunnel or caterpillar tunnel as better; however, that is more infrastructure than I want to deal with for a surprise frost. Low tunnels cost more, and then there is the hassle of setting them up and taking them down.

Whether you are a market grower or home gardener, I think you will appreciate the features of frost blankets:

• Quick and easy to use

• Reusable

• Fabric does not easily rip or tatter

• Extends the growing season for both fall and spring crops

• Provides freeze protection and minimizes plant burns 

• Helps hold in heat

• Porous fabric allows rain and overhead irrigation to pass through

• Helps prevent erosion due to heavy rainfalls

• Keeps insects and other unwanted variables off plants

• Helps to overwinter ornamentals and other perennials

• Polypropylene felt material allows a percentage of light to pass through

Frost Blanket Weights

The weight or density of a frost blanket is directly proportionate to the frost protection it provides. They can also be layered for added protection. Use the chart to select the blanket weight that suits your needs:

When to Use Frost Blankets for Plants

I recommend using frost blankets anytime there is a potential of freezing or near-freezing overnight temperatures and you want to protect your plants. They are great for protecting seedlings or newly transplanted plants from an unexpected spring cold snap and saving fall garden plants from a frost.

I like to apply frost blankets during the daylight hours and remove them after the sun comes up the next day. To be effective, you need to have plants completely covered before the frost sets in, and leave them covered until all danger of frost has passed.

How to Apply a Frost Blanket

One of the biggest mistakes I see gardeners make is not buying a large enough size. It’s much better to have the frost blanket be too big than too small. Ideally, you want the frost fabric to wrap over the entire space. 

1. Spread Out - Unfold the frost blanket and lay it directly on the crops you want to protect. 

2. Anchor Down - Use landscape staples to secure the frost blanket to the ground at 5 to 10-foot intervals. To adequately protect plants, the fabric needs to cover the top and wrap the sides to create a basically air-tight space. If you simply drape fabric over the top of the plants, as the cold air sinks, it will get under your plants, and you might as well not have covered them at all.

Pro-Tip: You can use frost blankets to make low tunnels. Simply drape the frost blanket over low tunnel hoops and anchor it down to the ground on all sides.