Early Frost! This is How we Protect Crops 1


frost on a leaf


This past weekend we got frost. Sigh.

This is pretty early, though there was one other year since we started Broadfork Farm that we had frost around the same time.

When there are warnings of ‘chance of frost,” we tend to get them.

And when we’re checking the 7 day forecast at this time of year and see that a night might get down below 8C with clear skies, we get mentally prepared for the worst. We live in a part of the region that’s fairly susceptible to getting colder than areas around us. Coupled with the late frosts of the spring (we had nights that hovered above and below 0C until the Summer Solstice!), it was a shorter frost-free season than we’ve ever had.

Luckily, not all of our crops are sensitive to frost and we do have an abundance of floating row covers (lightweight fabric) that can protect crops –to a degree- from frost. So after the market on Saturday, pretty tired from being up since 3:30 am, we went around covering the frost-sensitive crops we hoped to save.

If it’s really cold, any place that the fabric touches the plant will probably damage the plant. This definitely happened on many of our plants protected by the floating row cover, but they didn’t die.

On the first night of frost, Saturday night, the temperature went down to -1.5C. The next night, it went down to -2.6C.

In addition to the floating row covers, we had another frost-damage-protection-strategy.

Frost Irrigation

For the first time ever, with our new irrigation well and overhead sprinklers set up to overlap on one of our fields – we tried frost irrigating, the way it’s meant to be done.

In the past, we have watered some things right before the sun came up and hit the frost – more to wash off the frost. Which sometimes worked ok, but it depends a lot on the temperature in the morning.

This time, we turned the sprinklers on in the night right before the temperature went below 0C. We have temperature sensors on our farm that enable us to do this. Then we kept the irrigation going until the sun was up and the temperature was back up above 0C.

Doing this creates a scenario where ice builds up on the plants and, though it seems counterintuitive, protects the plants. It’s actually incredible – the plants that were covered with ice looked perfect the next day. We harvested fresh beans that were perfect from this section, where the beans that weren’t frost irrigated are now completely dead.

You can see in this picture – there was one bean plant at the end of this row that was outside the sprinkler radius. It’s all wilted. But the rest look the same as they did before the frost.

A bean plant killed by frost next to perfectly healthy bean plants

Check out this video farmer Bryan took early in the morning, before the sun hit the plants, while the sprinklers are still running and the plants are covered with ice. It’s incredible!

Extra Resources

And if you’re interested in learning more about this frost irrigation technique, here are webpages to check out:



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