By all rights, the green, purple, yellow and dragon tongue stringless beans in the driveway field should be black and withered from last weekend’s frosty nights. As should the tomatoes on the other side of the drive. After all, we hit 34 degrees two nights in a row. The basil, smartweed and Johnsongrass all got zapped, and so should have the beans. Frost is a not-so-funny thing and hard to figure out.
This crop of beans was a gamble in the first place. John had the seed and wanted to use it rather than risk poor germination with year-old seed next year. The ground was well prepared for a planting of cold-tolerant fall crops, so he planted the beans to “see if they will make” before cold-killing temperatures would wipe them out. We figure on first frost in mid-October but are not surprised if it comes earlier in the month. (Last year it was September 27!)
There was a better-than-average chance that the beans wouldn’t make their deadline, but we looked upon hope. They were good-looking rows of vibrant, green plants with no weeds, partly because of good field prep and partly because weeds are less aggressive this late in the season. Then three or so weeks ago, we could see blooms from the road. Looking down in the rows, they were loaded. I had never seen so many blooms on one plant in my life, and there were thousands upon thousands of plants.
So close but so far. Was time on our side? The weather forecast was calling for frosty nights before the flowers could self pollinate and make fruits, as the maturity rate slows with declining temps.
Frost figures on fuzzy math when it comes to predictability. All plants are pre-programed with a critical temperature that will kill their leaves. We have a chart, though there are varietal differences that we have learned the hard way.
Frost damage comes as cellular fluids freeze in the declining temperatures. Molecular function seizes and chards of ice rupture cell walls as fluids expand in the freezing process. Some plants are damaged well before the freezing point of water, at temperatures in the upper 30s, even 40 degrees F for basil.
Sometimes we can get down to 33-34 degrees and frost not form; other times, 37 degrees wipes out all the summer stuff, beans, tomatoes, smartweed, etc. Factors at play in the calculus of whether we’ll see frost damage or not include air temperature, wind, stage of plant maturity, plant cultivar, soil moisture, plant moisture, aspect, slope, elevation, treescape and this thing called radiational cooling, related to cloud cover and soil temperature. The only way I can explain it is: On a clear night, if we suspended a roll of aluminum foil over the row, those plants would avoid frost damage compared to their contemporaries in the adjacent rows. Plant variety and stage of maturity are the only ones we have any say in the matter, sometimes. So, we go on charts and hunches and favorable field working conditions and roll with the punches. Farming requires a strong constitution, which comes from farming.
Our little bean patch happens to be the crest of the ridge of Cane Run watershed, making it the highest point around, with a gentle western slope down to a tree line along the housing development. The crest must be what saved them. Frosty conditions settle into lower-lying lands, pushing the relatively warmer air up the slope, where it stays warmer longer. In this case, our beans and tomatoes eked by. Summer was still in play.
Each morning on our walk, Ann and I would check the beans and surprisingly find no frost damage. On closer inspection, we saw the miniscule little beans, a half inch long or less, protruding from the flower. The beans that should never have come to be, were right before our eyes. With a two-week window of no frost in the forecast, there was only one thing to do: Go all in to help these beans thrive.
It has been extremely dry, but since we didn’t think they were gonna make it, we hadn’t worked on setting up the irrigation as other crops needed it, too. With this surprise bean sighting, John set up the traveler irrigation sprinkler to give them a good shot of water, and with the above-average temps this week, they elongated and filled out nicely.
Everybody is excited about getting a good picking of beans on Friday, ahead of the next predicted frost, which is Saturday morning. Because they have become the bean that could, we will pull frost-protection blankets over the crop after harvest to give them their best chance of fending off the cold one more time. It’s a lot of work for a one-night frost scare, but it’s the least we can do, to honor these plants that have given their all. If all those little blooms make a bean, it will be the best green, purple, yellow and dragon tongue bean crop raised on Elmwood Stock Farm this year.
The tree leaves are seemingly changing by the hour, so heavy frost and freeze is not far off. It’s not very often we get to have fresh-picked beans and tomatoes and cabbage and spinach all at the same time. Look for these magic beans in your CSA share, and we’ll offer them in the online store if they are plentiful. I hope that the hard work put us in a position for good things to happen.
Thank you for your support so we can continue our farming habit. —Mac Stone