Handling fall frost

Saturday night we had a good, solid frost here in the valley. It wasn’t our first, we’ve had three light frosts since September 14, but it was by far the strongest and enough to end the season for a number of things. We knew it was coming and prepared as much as practical, including making some choices on what to protect and what we were ready to let go. The average first frost in central Missouri is October 15, while northern Missouri averages around October 1. Given that our narrow valley puts us in a climate setting significantly north of our actual location, an early October frost isn’t terribly unusual.
We’re used to the weather patterns here, in which a clear, still night can result in a frost. Fall always brings a pattern of strong cold fronts that sweep through, with clouds clearing rapidly post-front into a still, clear night that allows cold air to pool and settle on our narrow valley. Any time the overnight  forecast for Columbia reaches 40 or below under these conditions, we know to expect frost. With a forecast of 37 for Saturday night, we knew it would be a real freeze.
Sure enough, when we went out at dawn, frost extended throughout our main field and up the pasture slope beyond. Above left, a frozen-solid sheet protecting tomatoes, taken near 9am as the sun finally started to thaw things out. Above right, some very nice frost crystals on bush bean leaves. We also had a few rows of new kale and collard transplants, which normally can handle frosts, but were so young we covered them just in case. Their cover was frozen solid both nights, but the plants are fine. We hope to be harvesting these for CSA in early spring.

 We made some choices on what to protect and what to let go. Our tomato plants are mostly lush and healthy, but some recovered better than others from the August heat wave that stopped all flowering and fruiting for a while. The southern end of the main tomato rows, to the right in the photo above, look nice but have almost no fruit on them. The northern end is loaded with green fruit we hope can still ripen, so we focused our efforts on covering those and left the others open; they won’t be doing much more anyway. You can see various row cover fabrics and cheap sheets covering the better tomatoes in the middle distance (row cover at back is over cabbages and greens for insect protection, not frost). In this photo, too, you can clearly see frost extending across the area.

 The zucchini we decided to sacrifice. This final planting has been producing amazingly, very stable and healthy for a long period of time, but sales have been going down significantly. We pick these daily to get the most efficient harvest of high-quality baby squash, and that isn’t economically efficient if people don’t buy them. So over the last week we’ve been paying less attention to them, and let the weather have its way with them. We salvaged one last bulk harvest of all sizes, which will feed a happy pig for a few days.
 The peppers, on the other hand, we definitely wanted to save. Peppers mature very slowly, and though these have been producing well for us, they’re still loaded with green fruit that we want to give every chance to mature. So we draped row cover over these, pinning it in place on the trellis string with clothespins, both Friday and Saturday nights. This worked; despite the zucchini freezing solid in rows 30+ feet uphill, these suffered little to no damage. With at least one more week of warm sunny weather coming up, we’ll get a lot more peppers now.
We spent Sunday morning with our regular work crew, cleaning up the frost-killed plants, mostly tomatoes and zucchinis. After stripping the fruits for pig food or our kitchen, we chopped the large, viny, bushy plants into shorter chunks and trucked them up to a high ridge far from the field. We’ll compost all these remains, but don’t want them sitting around near the field spreading insects and disease. Filling the truck multiple times involved some fun stomping down of the remnant to squeeze more in, feeling like an old-time grape stomping or hay-stacking.
Many other items don’t care about frost, or were already dealt with. Leeks and parsnips actually benefit from a few freezes before harvest, and many fall items like greens, chard, and cabbages don’t care. Sweet potatoes and winter squash were mostly harvested already and are currently curing for proper storage and later distribution, though we covered some remaining winter squash to allow more to ripen.
The first real frost always creates a pulse of urgent work, but afterward it’s nice to start cleaning up and finishing beds for the winter. We’re mostly grateful for the continued dry conditions (~2″ of rain in both August and September, with no rain since 9/18) as it makes fall work much easier and cleaner. Conditions are perfect for cleaning out beds, spreading & incorporating manure, getting cover crop seeded, and more. Eventually we really need some rain for the health of pastures, fruit plantings, and more, and just so we can finally take a break indoors, but in the meantime we’re really getting work done and moving nicely toward next year.

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