As the days and nights get cooler, the chance of frost becomes an increasing possibility and threat damage or kill off tender annuals such as tomatoes, basil, and squash. Here in Toronto, our historic first frost date of the season is October 6th. This year for 2013, we’re expecting to have a pretty average fall in terms of temperature and precipitation.When the cool weather comes, here’s what you can do to protect your tender plants from the fall weather:

1. Place a bed sheet, lightweight curtain, floating row cover, or large piece of fabric over your plants.
Think of this as putting an extra blanket on your plants, trapping both warm air and moisture around your plants. For additional protection, place several large buckets of water in your garden during the day to let them capture some of the heat and warmth of the sun. Since water holds onto heat better than air, this will help moderate the temperature at night.

2. Move potted plants into the garage.
Bring in your herbs at night and take them back out once the weather has warmed up in the morning. This is especially useful for annuals like basil and rosemary as well as for tomatoes, peppers, eggplant (all in the nightshade family).

3. Harvest tender plants early.
For sensitive plants growing in raised beds or directly in the ground, harvest additional greens or harvest fruiting plants early and allow them to ripen indoors. It’s better to have extra basil on hand than a dead basil plant!

4. Water/irrigate your garden.
According to Cornell University (pdf link), moist soil can hold four times as much heat as dry soil and keep air temperatures 2.7 C warmer until 6am the next morning. Give your plants a good soak late in the day to help them get through a cool night.

5. Erect a cold frame, tunnel cloche, or greenhouse around your garden.
There are many options when it comes to cold frames, cloches or greenhouses. You can build your own using free garden plans online (do a quick online search), purchase commercial easy-to-assemble kits, or upcycle your own using things like old window panes, translucent weatherproofing plastic, and more. We offer two products from our online store: a 3′ x 3′ cold frame and a larger easy-to-assemble greenhouse available in a variety of sizes.

Here are some of the most common plants you should think about protecting from frost this fall:

  • Basil
  • Beans
  • Cilantro
  • Corn
  • Cucumber
  • Eggplant
  • Lettuce
  • Melons
  • Okra
  • Peppers
  • Pumpkin
  • Swiss chard
  • Tomato
Cover Image by permiegardener, used under its Creative Commons license.

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