How to Protect Your Plants From Frost

Whether you’re planting in the early Spring or Fall, there are things you can do to be prepared to protect your plants from frost.

Gardening is always a gamble. You never know when a surprise cold snap is going to come, how many weeks of good weather we’ll have, or if a freak snow storm is going to wipe everything out.

I like this resource by the Farmer’s Almanac that gives you the estimated last and first frost dates for your area: Frost Dates.

Simply put in your zipcode and click “Change”.

However, your local topography can affect your likelihood of frost or a hard freeze.

The last Frost Dates given by the Farmer’s Almanac are for a light frost – 29° to 32° – which will likely kill tender young plants that are not protected.

Moderate freezes are between 25° to 28° – which will likely kill most plants. Hard frost is anything colder than 24° and will cause severe frost damage.

For more info on how to grow specific vegetables, check out my series: 30 Second Guides to Growing Vegetables. 

Also take into consideration the individual plant. Hardy plants suitable for your zone may not need frost protection at all. However frost-tender plants may suffer from even a light freeze.

For those first early nights of cold weather, when there’s still weeks of good weather ahead, there are things you can do to ensure your young vegetable garden survives.

So keep your eye on the weather forecast for a freeze warning, and prepare with the tips below:

How to Protect Your Plants From Frost

Water A Day or Two Before

The first thing you want to do at the first threat of frost in the forecast is to water plants a day or two before.

Not enough that you’ll have wet soil under the freeze, but enough that your individual plants will be healthy.

This may sound counter-intuitive, but perky, healthy plants are more likely to survive cold temperatures.

If the days are in the 40’s and 50’s, but temperatures dip down to 30’s in the cold nights, generally speaking it won’t be cold enough for long enough to freeze any moisture in the soil.

Mulch

The best way to protect cold-sensitive plants is to, spread compost, mulch, leaves, or other organic material around the base of your plants.

Build it up as much as possible around the plant without suffocating it.

This will provide insulation from the cold air to the vulnerable stalks of your plants.

Cover

In the olden days, gardeners had glass domes they would place over each plant to act as a mini greenhouse.

While these are gorgeous (read: I need some) they’re not very practical for today’s gardener.

For additional protection for frost-sensitive plants, a frost cloth, row covers, an over turned flower pot, old bed sheets, towels, newspaper, or milk jugs can work just as well.

You can find these in your local garden centers.

Word of caution: when you cover plants, you want to create dead space between the plant and the plant cover.

This dead space acts as insulation.

Be very careful not to allow the protective cover to touch the plant at all.

Uncover in the morning as the temperatures rise to prevent over-heating your plants.

Heat

For extra protection from the danger of frost for small plants or tender perennials is to provide a source of heat.

If you have heat lamps, or even Christmas lights that give off some heat you can string these around your plants, under your covering if you’re using a bed sheet or tarp.

Be careful the lights aren’t going to catch your cover on fire!

Another trick for capturing and distributing warm air without the risk of catching your entire garden on fire is to fill large plastic jugs with water earlier in the day and spread out among your plants.

The water will heat up in the sunlight and gradually leach heat out throughout the night.

Hopefully these few tricks will help you be prepared to protect your crops and extend your growing season.