Planting a Fall vegetable garden is always a gamble. You never know when the first frost 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.
The Frost Dates given by the Farmer’s Almanac are for a light freeze – 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. Severe freezes are colder than 24° and will cause severe frost damage.
For those first early nights of frost, when there’s still weeks of good weather ahead, there are things you can do to ensure your Fall vegetable garden survives:
Water A Day or Two Before
This may sound counter-intuitive, but perky, healthy plants are more likely to survive temporarily harsh conditions. If the days are in the 40’s and 50’s, but the night drops down to 30’s, generally speaking it won’t be cold enough for long enough to freeze any moisture in the soil.
If at all possible, 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 to the vulnerable stalks of your plants.
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. However, frost blankets, old bed sheets, towels, newspaper, or plastic jugs can work just as well.
Word of caution: you want to create dead space between the plant and the cold outer air. 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.
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 heat 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.