Batten Down the Hatches!
When air temperatures drop below 32˚F (0˚C), frost happens. The frost to watch out for is the harder sort, when the temp drops even lower to 28˚F (-2˚C) or lower for 4 hours or more. A number of plants can survive a frost in the low 30’s that lasts a few hours, but they’ll be damaged by lower temperatures because the water within them will freeze their tissues and burst… there’s rarely any coming back from that. Some plants can take those cold temps though, including any varieties that you can plant as soon as the soil is workable - this is noted on the back of the seed packets.
There are things you can do to protect your gardens of promise!
It all begins with noting the annual average last frost date in your area, and then watching the weather reports like a hawk for 2 weeks prior to and after that date. Late-season frosts can be a real heartbreaker when they take out a community of plants you are gently cultivating. If low temps are predicted try the following:
- When frost is predicted water your plants in the mid-afternoon to allow them and the soil to absorb the moisture, but don’t drench them too late in the evening! The right balance of absorption will help hold the heat of the day.
- Invest in a piece or two of row cover, farmers use this for season extension. This is available from Johnny’s with different levels of temperature tolerance, but check with your local nursery. Tuck your plants in when the sun goes down to protect them from lower temps, but be sure to uncover them in the morning so they don’t overheat.
This is not necessary for established brassicas (kale, cabbage, broccoli, or mustard greens), or root veggies (beets, carrots or radishes) all of which can survive a light frost. If you have plant starts such as corn, beans, new young greens, or cucumbers, you’ll want to take extra measures before transplanting, or wait until it’s definitely after the last frost and direct seed them (which we recommend anyway). If you don’t have row cover handy you can use a sheet or blanket, but be sure to drape it over something like a trellis, tomato cage, or even a couple of chairs so it’s not resting on top of the plants! Weigh the cover down with rocks or branches so air isn’t flowing in. Basically build a blanket fort for a night, it might look weird to the neighbors, but trust us, you’re becoming part of an interesting club, welcome to the seedy side of life!
- You can also add some heat to the situation, such as a string of older non-LED lights, strung carefully between the plants, not touching them or the ground. Be sure to turn them off in the morning, and uncover the plants to allow the sun to warm them naturally.
- Provide a more robust cover using storage totes, garbage cans, or even plastic cake covers as cloches (a small translucent cover for protecting plants). Weigh them down if wind is predicted.
If you tried jug gardening this season you’ll note that the seeds pop when they’re ready, and if you’ve already begun transplanting some cold-hardy varieties you might notice how well they do with weather resilience! If you didn’t, you can start saving your jugs now for next season! If you did start your seeds using jugs, you may be able to get a little more use out of the jug as a cloche, provided your plants haven’t already grown too big for such things!
Adapted from Grow a Good Life,"6 Ways to Protect Plants From Frost"