Types of Frost Protection for Tomatoes

Tomatoes cannot withstand frost. Choose from different types of frost protection to safeguard young plants in the spring and mature plants in the fall. By planning ahead, you can be ready when the forecast doesn’t look good for tomatoes.

I. Individual plant covers

Individual plant covers are used to protect individual plants from frost. They are especially helpful if you grow tomatoes in containers or pots, if you grow tomatoes on a patio or balcony, or if you grow just a few tomato plants in the garden.

What to know about individual plant covers

  • most are made of nonwoven polypropylene fabric, which is lightweight and breathable
  • most have drawstrings and cord locks to help fit covers onto plants and hold them in place
  • they are available in various sizes for whatever size tomato plant you grow
  • they are reusable from season to season
  • they provide as much as 5-10 degrees of frost protection

II. Row covers for frost protection

Tomatoes planted in garden rows can be protected from cold temperatures and frost with row covers.

Soil is warmed during the day by the sun as it penetrates row covers.

At night, the captured heat in the soil helps protect plants from frost.

Row covers also provide a layer of protection from cold temperatures and frost.

Two kinds are most common: floating row covers and tunnel row covers.

Floating row covers

Floating row covers are sheets of lightweight fabrics that are draped directly over tomato plants. Because you adjust the height when you set them out, they are suitable for both spring tomato seedlings (which are short) as well as mature tomato plants (which can be quite tall).

  • Most floating row covers are made from light-colored, nonwoven, breathable fabric, which allows them to transmit light. That means they need not be removed during the day but can remain on plants for an extended time.
  • Some have drawstrings and cord locks to help fit row covers onto plants and hold them in place. Or you can secure them with earth staples icon.
  • Row covers are reusable from season to season.
  • They can provide up to 8 degrees of frost protection.

Tunnel row covers (framed row covers)

Framed row covers (tunnels) cover an entire row of tomato plants or seedlings. Most tunnel row covers are not tall enough to accommodate mature fall tomatoes. They are best used in the spring to protect tomato plants from late frost. Tunnels protect plants from wind as well as frost and cold temperatures. You can purchase pre-made tunnel row covers or make your own.

  • Tunnel row covers are made of wire or fiberglass hoops covered with nonwoven fabric or plastic.
  • Light-colored or clear material allows light to penetrate tunnels.
  • Tunnels can remain on rows for an extended period of time, allowing interior air to warm.
  • Tunnels can be ventilated to prevent overheating during the day. Poke holes in plastic covering to prevent overheating inside. (Breathable fabrics are less likely to overheat the tunnel interior.)
  • Christmas lights or a spotlight inside tunnels can provide extra warmth.
  • Remove tunnels when the danger of frost has passed.

Make your own tunnels

Buy inexpensive wire or fiberglass hoops to make your own tunnel row covers.

  • Set hoops three to five feet apart along the tomato row or raised bed.
  • Drape lightweight netting, garden fabric icon , or plastic lengthwise along hoops.
  • Bury edges of garden fabric icon or plastic into the soil or secure them with earth staples icon. When using coverings on raised beds, you can also attach covering edges to its sides with earth staples icon.
  • Poke holes in plastic covering to prevent overheating inside. (Breathable fabrics are less likely to overheat tunnel interior.)
  • String Christmas lights or a spotlight inside tunnels for extra warmth.
  • Remove tunnels when the danger of frost has passed.

III. Water for frost protection

Water is a good insulator. It is able to absorb and sustain heat gathered from sunlight. In addition, when water freezes, it releases a small amount of heat.

Self-standing water tubes

Two products are favored by tomato growers to protect tomato plants by regulating the temperature around a tomato plant with water.

  1. Wall-O-Water is a self-standing set of clear tubes that surround a tomato plant. Tubes are filled with water, which warms during the day in the sunlight. Heat radiates at night to keep plants warm. Wall-O-Water has been effective in temperatures that dip down as low as 16ºF.
  2. Red Tomato Teepees icon operate on the same principle as the Wall-O-Water, but their tubes are colored red, allowing water to heat more quickly.

Both Wall-O-Water and Red Tomato Teepees icon are reusable in spring and fall and from year to year.

Spray

A new product called FreezePruf, when applied 8-12 hours before a freeze or frost event, can provide 2-5 degrees of frost protection to tomatoes. There’s a good deal of science behind the biodegradable product. Bottom line, simplified: FreezePruf dehydrates plant cells to help them tolerate a frost or freeze.

IV. Sheets, blankets, and clear plastic for frost protection

Some gardeners have success protecting tomatoes from frost the old-fashioned way – by covering plants with bed sheets, blankets, or sheets of plastic. The layer provides insulation, keeping cold out. This method takes a little bit extra work in removing the coverings during the day and making sure the plastic doesn’t touch plants.

Using bed sheets or blankets to protect tomato plants

If you choose to use sheets or blankets to protect tomatoes from frost, be careful of a few things:

  1. Make sure the fabric is not so heavy that it damages plants.
  2. Make sure fabric remains dry. Evaporation can lower the temperature next to the fabric.
  3. Make sure you remove fabric during the daytime so that soil can reheat and light can warm plants.

Using plastic sheeting to protect tomato plants

If you choose to use plastic sheeting to protect tomatoes from frost, be careful of a few things:

  1. Make sure plastic does not touch tomato plants. Cold plastic will damage plants at the point of contact.
  2. Make sure you remove sheets of plastic during the daytime so that soil can reheat and light can warm plants.


More on protecting tomatoes from frost and freezing

Protecting tomatoes from frost and freezing: the basics ...


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