Protecting Your Garden from Early Fall Frosts

So you regular readers might recall how very unhappy I was about the freak cold snap last fall that wiped out my garden a full 4-6 weeks earlier than it should have happened.  I’m still irritated about losing all those tomatoes.  I did cover a few plants as best I could with some old sheets, but I didn’t have enough to go around.  And because the temperatures dropped too much—to about 23-25°F—even additional measures might not have helped.  But they might have, and I wish I’d been aware of these other options for possibly protecting my plants and extending the harvest another several weeks. 

Irrigation.  The first step, regardless of which other measures you take, is to water the garden well.  Moist soil (not waterlogged) retains several times more heat than dry soil.  The heat is then released at night, keeping the temperatures up to 5° warmer.  This alone may be enough to save your vegetables.

Mulch.  Low growing vegetables can be covered with straw, pine needles, or leaves before an anticipated frost.  After the danger of frost has passed, the mulch should be brushed off to let the vegetables continue growing.  Leave the mulch on the ground surrounding the plants to help keep them warmer. 

Mini heat sinks.  Fill milk jugs with water and paint them black.  Position them in the garden to help protect the most tender plants.  They will absorb heat during the day and release it at night. 

Row covers.  Spread row covers over the tops of the vegetables and secure them to the ground with stakes or rocks.  Use old sheets or tablecloths, basically any light- to medium-weight fabric.  Agricultural row covers can be purchased in bulk online.  Be aware that most of these are for one-time use.  There are frost blankets that are more expensive but provide better protection and are reusable for several seasons.  (Actually, I just bought two this week, called the Planket, from Amazon.  Surprisingly, they're cheaper than they were last year, and I got a package that even included the stakes, normally sold separately.)  Plastic sheeting is another option, but it has to be kept from touching the foliage. 

Now imagine how much protection you can provide if you combine these measures.  Have milk jugs already painted and filled as you approach the end of the season so that they are warming each day.  When there is the threat of frost, water the garden well, and then mulch with straw.  Finally, spread the row covers.  Yes, it will take some time, but it will be so worthwhile to be able to protect the vegetables and extend the harvest. 

Tender vegetables must be protected from frost or harvested beforehand: 

• Beans
• Corn
• Cucurbits (cucumber, muskmelon, watermelon)
• Nightshades (eggplant, tomatoes, peppers)
• Okra
• Squashes (pumpkins, summer squash, winter squash)
• Sweet potatoes

Frost tolerant vegetables are those that can withstand a light frost, usually between 28-32°F: 

• Most root crops—beets, carrots, garlic, onions, potatoes
• Cauliflower
• Celery
• Chinese cabbage
• Lettuce
• Rhubarb
• Swiss chard

Hardy vegetables tolerate hard frosts and freezing temperatures (below 28°F) without damage for short periods:

• Most cole crops—broccoli, Brussels sprouts, cabbage
• Onion sets and seeds
• Parsley
• Peas
• Radish
• Spinach
• Turnips
  

Links to related posts:

Moving Vegetable Plants to a Warmer Zone