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How to Cover Plants for Frost Protection

In areas where a late spring frost or even an early fall hard frost can threaten garden and landscaping plants, there are ways plant lovers can protect them. Weather is unpredictable, even in those areas where plants are suitable for their growing zone. You can protect plants from frost if you are both prepared—and aware of the pending weather.

Soft woods, actively blooming plants, and potted plants are the most susceptible to frost damage. The greatest threat of frost usually occurs overnight when the temperature drops enough to freeze the moisture on plant leaves and buds. The signs of frost damage are usually visible within two to three days and include browned and mushy leaves and buds. To protect plants from frost, you will need to cover them to keep the moisture from freezing.

Plastic can be used to protect plants from frost, but it’s not the best or most effective material, and some expert gardeners warn against it. Plastic or vinyl materials do not breathe, causing moisture to get trapped inside. If the temperature drops low enough, the increase in moisture presents a greater threat to the plants. Instead of plastic, try using natural fabrics like cotton or linen, an opened burlap bag, or newspaper, as a covering to protect plants from frost.

A fabric covering will allow moisture to escape but will still protect plants from frost by preventing the freezing air from coming into direct contact with the moisture. Bed sheets work well for covering large plants and shrubs, as well as young sprouts. Newspaper can be used on low-growing foliage, but won’t stay on top of larger plants well.

In a pinch, you can use plastic sheets, but be sure to remove the plastic covers early in the morning to let the increasingly warmer daytime air reach the plants. If the threat of frost is prolonged and temperatures remain low during the day, be sure to use a fabric covering. When there is a threat of frost, cover your plants before sunset.

You can also purchase commercial coverings designed to protect plants from frost. These may be more attractive than other methods, but usually bed sheets or burlap work just as well. If your efforts to protect plants from frost fail, you will have to allow nature to take its course. Early spring perennial flowers like the daffodil, tulip, and crocus may be damaged for the current season, but they should return in good health the next spring.

Depending on the weather, some plants may peek out earlier than normal, only to be threatened by a late frost. In some cases, they will bud again but often they will die and you’ll have to start over. Typically, the more established a plant is, the better it will fare. If you have vulnerable plants that would be expensive to replace, it’s best to try to protect them.

The cold, cloudless evenings in the fall, winter and spring may be harmful to your plants. During the day, your plants and the soil absorb and store heat from the sun. As the day turns into night, your plants quickly begin to lose all of their stored heat. Clouds will help to insulate and slow the loss of the heat, but a cloudless, wind-free night will afford no protection from frost. The temperature within the soil and in the plant’s cells may even drop to a few degrees colder than the air.

As the temperature decreases, the moisture in the air condenses into dew, which then freezes when the temperature reaches 32 degrees F. on the plant surfaces. At 32 degrees, damage to most plants may be minimal and only affect a small amount of leaves. However, if the temperature drops far enough for the plant cells to freeze, non-hardy plants will die.

Frost can occur even in supposedly frost-free areas. It is important to heed the weatherman’s warnings of “a chance of frost,” and take precautions to protect your garden. It is possible to extend your growing season by several weeks if you are able to keep your plants alive through a single early frost!

36 Responses to “How to Cover Plants for Frost Protection”

  1. jstutzman says:

    Other ways to help your garden survive a frost.

    The best way to avoid frost damage to your plants is to grow plants that can withstand the frost. The term ‘frost hardy’ is often misleading because of the degrees of frost (i.e., light frost vs. hard, killing frost). It is a good idea to ask a qualified local nurseryman what is suitable to grow in your area. Even better, look around your own neighborhood, and see what survives and thrives in other yards and gardens.

    Choose varieties of plants that flower late, in areas where late spring frosts may occur. Some annual and perennial plants will survive frost on the foliage, but the same frost might kill any flower buds that have emerged.

    Cold air is denser than warm air, so it sinks to the lowest point. Low-lying areas of the garden can be several degrees colder. Consequently, frost may occur in these areas when there is no frost evident anywhere else in the garden. Plant tender species on higher ground or on slopes where the cold air will flow past the plants as it moves to the low point. Any sloping area is less prone to frost, because the cold air won’t settle there as readily.

    Precondition your plants to withstand cold temperatures by discontinuing fertilizing in early fall, so that no new foliage is on the plant when cold temperatures arrive. Older leaves are much tougher and more able to withstand frost.

    When frost is predicted, there are several things you can do to protect your plants:

    Water your plants thoroughly before nightfall. The soil will release moisture into the air around your plants during the night, keeping the air somewhat warmer.

    Even a slight breeze will prevent cold air from settling near the ground during the night. You can help keep frost from forming by providing this breeze with an electric fan. Be sure to protect the fan and all electrical connections from moisture and the elements.

    Cover up before dusk! By the time it gets dark much of the stored heat in the garden has already been lost. If you have time, build a simple frame around the plant, or row of plants. (Even a single stake can be used in many cases.) Then drape a cover of newspaper, cardboard, plastic tarps, bed sheeting or any other lightweight material over the frame to create a tent. If you don’t have time to create a frame, lay the protective cover directly onto the plant. This will help to slow the loss of heat rising from the foliage and the ground. Remove the covers in the morning, once the frost has disappeared, to let the light and fresh air back in, and to prevent overheating by the sun.

    For smaller, individual plants you can use glass jars, milk jugs with the bottom removed, paper cups turned upside down, or flower pots as heat traps. Don’t forget to remove these covers in the morning.

    You can collect heat during the day by painting plastic milk jugs black and filling them with water. Place them around your plants where they will collect heat during the day. Water loses heat more slowly than soil or air. This collected heat will radiate out throughout the night.

    Potted plants are particularly susceptible to frosts because the roots are less insulated. If you are unable to move your container plants indoors or under cover, remember to also wrap the pot in burlap or bubble wrap, or simply bury the pot in the ground, in addition to protecting the foliage.

    If your efforts were too late, or too little to protect your plants from a frost, resist the urge to cut off the damaged parts of the plants. To a certain extent, these dead leaves and stems will provide limited insulation from further frost damage. Your plants will still need to be pruned in spring.

    USDA Zone Last Frost Date
    1 July 15
    2 August 15
    3 September 15
    4 September 15
    5 October 15
    6 October 15
    7 October 15
    8 November 15
    9 December 15
    10 December 15
    11 No frost

  2. Ann says:

    When covering plants for frost, do I leave the frost protection bag on my plants all day or do I take it off in the morning?

  3. jstutzman says:

    Dear Ann, covering plants for frost is very simple. The night before the frost is expected, cover your plants. The next morning after the sun has risen, you can remove your plant covers. You continue this until the weather turns cold enough that the plant dies down for the year season.

  4. Linda says:

    I have a friend when it gets 32 degrees and below, run his yard sprinklers to put a coating of ice on the plants. What does this ice coating on the plants do to protect the plants? Is it better than covering them up?

  5. jstutzman says:

    I gotta think it’s harder on the sprinkler system than the plants!

    According to the US Dept. of Energy, depending on how long the temps maintain freezing and below, this is not harmful. Why? Well, the water in a liquid state has to undergo a physical change to transform to a solid. When it freezes it gives off heat energy during that transformation. Once the freezing process stops, the ice will fall to ambient temperatures, so an extended period of freezing would require a continued spraying. The extended spraying, however, would create an increased amount of weight from the ice load, risking damage to the plant from breaking branches. But in addition to the energy released during freezing, two other reasons apply. Ice has a low thermal conductivity, especially if sprayed on in the form of a “snow” and the ice/snow helps to protect the plant from wind, which will wick moisture and heat away (that dreaded “wind-chill” factor). It’s why igloos work or why you burrow into the snow when caught in a snow storm. If you don’t want to water your plants in the freezing temps, make sure that the ground has sufficient moisture by watering the ground around the plants. If you have had a period of drought, your plants may already be stressed and less able to endure a sudden freeze, so in general keeping moisture consistent at the root level is also important.

    Because of watering limitations in commercial use, new sprays are being developed to help plants endure sub-freezing temps. Covering
    plants with cotton fabric or plastic to protect against cold and frost is a simple physical barrier against the elements, but be sure to remove in the mornings so sunlight can warm the soil and air can circulate around the plants.

  6. Jan says:

    Can plant blankets stay on the plants to protect them from frost for a few months without removing them, or should I remove every day?

  7. jstutzman says:

    Jan that is a good question and one that needs some more information to answer fully.

    If your blanket is covering something like a hydrangea or semi-hardy shrub, you put them on after there has been sustained cold and leave them on. Depending on your location that could be anywhere from now until the first of the year. I have some that cover a couple hydrangeas but I do not completely seal them up or fill with leaves until we have consistent temps in the 40s and below in the daytime, usually late December.

    If you’re covering cool-season, late fall crops then it would be best to remove or at least open them during warmer, sunny days so you don’t run the risk of overheating the plants. They could be left on if the days are cold and blustery. I would treat them similarly to cold frames, just not letting interior temps get too high. The blankets are designed to keep the frost off the leaves but will only do so for a short period; once the weather turns really cold the ambient air under the blanket will be too cold and the blanket can no longer protect the plants.

  8. Rob says:

    The best way to protect plants from a hard freeze is to build some sort of frame, PVC works great, to keep the fabric off of the plants. Plants tend to burn where the fabric comes into contact with them. For prolonged frosts or hard freezes the best thing to do is to cover the plants and build a tent like structure to keep as much breeze out as possible, then put a spotlight underneath to increase the temp inside the tent. Fabrics that breathe work best like cotton or frost cloth.

  9. nawang says:

    I have burlap covering my plants, do I need to take the covers off during the day.

  10. jstutzman says:

    I would not recommend leaving burlap it on for more than 1 day

  11. Bobby De jesus says:

    i have a guava tree (about 4-41/1 ft high, about 5ft wide. what is the best way to protect if from frost. the leaves are beginning to turn brown and leaves are crumbling when you press then in your hand

  12. lmaloy says:

    I bought these from your site the first time last year after losing plants from ice here in OK. I won’t ever be without them again! I used them according to your recommendations and then dried and aired them out before putting them in storage. I didn’t lose any plants last year and I’m about ready to have to get them out of storage again and I think I’ll order a few more. They are well worth the little I paid for them. Thanks!

  13. jstutzman says:

    Since I am unaware of the location of the tree or its circumstances, I can offer only some general advice about protecting subtropicals from frost.

    If the plant is in the ground, then overhead protection, such as a frame over the plant covered with fabric, will provide additional protection during freezes, and electric lights can be included for added warmth. We sell some excellent options for plant covers. Potted plants can be moved to a more protected site if necessary. The best option is planting on the warm side of a building or structure to provide some frost protection for guavas in cooler areas.

    I hope that helps with your tree.

    Karen

  14. [...] The soil will release moisture during the night, keeping the air around you plants warmer. Second, cover plants with a bed sheet or plastic. Non-plastic materials are better, as they allow the plants to breathe. [...]

  15. Larry says:

    We live in Las Vegas and have a couple of cacti (organ pipe and Peruvian Apple) that can be hurt by frost when our temps get to 32 or so a few times during the winter. I cover these with burlap and leacve the burlap on from late November unitl late February when it begins to warm up. It works fine. My bogainvillas I cut back then cover with burlap and leave on all winter (2.5-3 months) with no negative effects. The pigmy date palms we have near the front entrance are especially suseptable to cold. I bought 6′x5′ commercial covers (appear to be made of Tyvek-like material)and only drape those over the palms (7′ high by 6′ wide) on evenings when temps are to go below 34F. This works well. I have installed hooks on the ground to hold the covers should it get windy.

  16. Stewart says:

    When protecting plants from frost with bed sheets, do you have to uncover frequently or can the cover be left on the plant?

  17. jstutzman says:

    Stewart,

    Bed sheets are great temporary covers for frost protection in the late fall and early spring but they don’t make the best covers for a long-term basis. The fabric is generally not porous enough to allow sufficient air circulation and when wet could become too heavy and cause stems to break. During the period of the seasons when patchy frost happens, cover the blooming, or pre-harvest plants in the late evening before the frost occurs but remove the sheet in the morning as the sun comes back up. Recover the next evening if needed. Spraying the plant with water prior to covering is also helpful for short-term protection.

    For all-winter protection of tender perennials and shrubs, use either our Natural Burlap or other specially-made plant protection fabrics.

    Happy Gardening,
    Joe

  18. Helen Del Rio says:

    Can strings of little white Xmas lights strung around a potted Bird of Paradise plant be enough to protect them from freezing?

  19. jstutzman says:

    Christmas lights, if enough were used, may protect from light frost; however they will not stop a freezing issue.

  20. [...]How to Cover Plants for Frost Protection | Garden Harvest Supply[...]…

  21. Russel Smith says:

    Have you tried the Grow it Now! Plant Protector? It is a miniature greenhouse that you put over your plants, anchor it down with garden staples and pile dirt up the sides. You leave it on the plant for the first 4 – 6 weeks, it promotes and stimulates germination, protects against heavy wind, rain, snow and cold weather temperatures. We planted our spring 2011 garden using the Grow it Now! Plant Protectors and were able to start our cold-hardy crops as soon as the soil could be worked, for southeast Idaho that was March 19, 2011. We were harvesting 9″ broccoli and cauliflower by June 13, 2011. Our tomatoes we started the first of May when around here you are nuts to start them any earlier than memorial day. We had the most bountiful harvest of tomatoes we have ever had in our 15 years of gardening here in Idaho. I highly recommend the plant protectors and hopefully it will save you some time only putting them on once and leaving them on for the first 5 weeks.

    Russel

  22. feng shui says:

    feng shui…

    [...]How to Cover Plants for Frost Protection | Garden Harvest Supply[...]…

  23. john says:

    Will the plants covered to protect them from frost/snow survive if no light is on them for a few days? Or do you remove covers even if temp is below freezing?

  24. jstutzman says:

    Yes your plants will survive for a couple days being covered. Covers do well for frost; however you should keep in mind that they only give a couple of degrees protection against freezing.

  25. Jayne says:

    I live in Iowa and deal with frost often. Daytime highs are now 40’s and night time lows are 25 to 38’s. Because the frost is hitting early this year I am trying to keep them safe from frost until I can harvest the produce. (Tomatoes and peppers) I came up with the idea of covering the plants with thick plastic first and then blankets. I remove the blankets somewhat during the day and pull them back on each night when needed. Then the plastic can stay on during the day to keep some of the heat in. Is this a good idea or am I wasting my time with this method?

  26. cynthia says:

    i have ivy and aloe vers big potted plants out side can i cover them with anything that will keep them though the frost to big to bring inside

  27. jstutzman says:

    If you do not have a frost cover, you can certainly use an old bed sheet and drape it over the plants.

  28. moe says:

    will a covered porch suffice for hanging plants?

  29. jstutzman says:

    Moe, anything that is hanging over the plants will protect it from frost.

  30. Darold says:

    So I have a caged in area with black snow fence to keep rabbits and such out, if I were to lay a sheet over the top, covering the area, would that do? Or is it necessary to cover up the sides as well. I also have a 1500 watt construction light I could put in the area…

  31. jstutzman says:

    Darold, laying the sheet over the top would be fine for frost. If the temps drop below 33, you would want to put a heater underneath as well.

  32. Catherine says:

    Hi,
    Plastic is not an effective method for protecting plants from frost. Plastic has no thermal resistance; which means that although it stops air movement, it does not keep heat around the plant. The frost will effect your plants wherever they touch the plastic. Old sheets, lightweight blankets or newspaper will effectively protect your plants against frost.

  33. jstutzman says:

    Catherine, you are correct. Plastic is a poor method of covering plants in harsh weather.

  34. Sam says:

    My mango plant is an experimental project! It’s 2.5 ft tall with two twigs / branches. I’v planted it in the SW corner of my backyard. NJ zone is 7B. My plan is to:
    1. Lay down flat on the ground tote bags filled with thermo-cole around the twigs, and place some heavy firewood on them. This is to keep the top soil warm.
    2. To wrap-up the plant with soft cotton cloth from base up and leave it there for the entire winter.
    3. Run a hose pipe to the base of the plant under the tote bags to water the plant periodically like once in 10 days. Not sure whether the residual water in the hose will freeze and burst it.

    Would that help save the plant? Mango plants may survive the New Jersey harsh winter weather indoors but I’m not sure about outdoor especially when it is rooted directly into the ground soil and not in a pot or container.

    Your thoughts would be appreciated. Thanks

  35. Lilac Vinyl Sheet Piling…

    [...] fe from frost until I can harvest the produce. (Tomatoes and peppers) I came up [...]…

  36. Eating from the Garden says:

    […] Our early spring is, in fact, going to give way to some colder nighttime temps, so we may be getting out the sheets and tenting a few things, especially my beautiful lilac […]

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