By Kelly Lecko
Frosts have hit the AMI Urban Farm at VSDB more often than you think. Because our farm is located in a cold sink, it tends to collect cold air and actually be colder than other parts of Staunton. When the Weather Channel predicts a low of 40° F for Staunton, the Farm Team prepares for 32° F to hit our farm. But why? Did you know that cold air sinks and flows like water? So naturally, because our Urban Farm sits in a floodplain, air tends to flow freely down the big hills towards the creek and settle onto our garden beds just as water flows through a watershed.
But alas, I digress. I meant to tell you about the vegetables, not the microclimate. So- the vegetables. Are they all frozen? One train of thought could lead you to the conclusion that many frosts would weaken the plant and thus make it less desirable for us to eat. But the miracle before your eyes (and on your tongue) is that the spinach tastes better post-frost. Now, isn’t that strange?
Here is what’s going on:
As Nick and Trevor and I put some beds to sleep for the winter, the kale, collards and spinach are ramping up their sugar production and accumulating it in their tissues. Some vegetables, such as carrots and potatoes, break down their stored starch and convert it to sugar which is then sent to the cells. Just as salt can help reduce ice on the road, sugar helps plant cells resist frost damage. Even though plants aren’t “warm blooded,” they can keep themselves from freezing when temperatures are still relatively mild. Kale is said to be able to withstand temperatures down to 10° F! Isn’t that truly awe-inspiring?!
Below is a list of vegetables we are growing on the farm that are especially frost tolerant. There are certainly more varieties, too, like Brussel Sprouts, which we do not have growing but are definitely great end-of-season treats*. We will be harvesting these greens as long as we can, and plan to leave them in the ground to surprise next years’ Fellows with early spring greens :) (Yes, these same veggies are the first ones you can plant in the spring!)
Brassica Family:Broccoli, Cabbage, Kale, Radishes, Turnips, Collards
Amaranth Family: Spinach, Chard
So this winter when you plan next season’s garden, make sure you get excited for the first and last crops available. Not only will they be providing you with great nutrition in early spring and winter, they will be full of sugary sweetness that might even get the kids to eat their vegetables!
*Please note that even though a vegetable is considered frost tolerant, it doesn't mean all varieties of that vegetable can withstand the same temperatures. It is important to pay attention to planting times and days to maturity (found on the seed packet) in relation to your area’s frost dates.