Recently I reported on which crops were still alive after two nights at 14F (-10C) and What’s still alive after two nights at 4F? We’ve now had the Polar Vortex, which brought us two nights at 4F, on 1/6 and 1/7. Then it got even colder.We got the Big Round 0F 1/22-1/23, then a few nights at 5F or 6F, and then the big insult: -4F on the night of 1/29-30.
What’s still standing?
The Tyee spinach under thick rowcover has sustained big damage, showing as patches of beige dead cells. It will recover. Meanwhile we can eat from the more-protected spinach in the coldframes and the hoophouse.
The Vates kale without rowcover is still alive, but badly damaged. The big leaves are crunchy and brown round the edges, and some of the inner leaves are dead. I hope it will grow back, but we won’t be able to pick that for a while. The Beedy’s Camden kale looks worse – the big leaves have died and flopped over. Not sure if it will recover.
Many of our strawberry plants look dead – very disappointing!
Our hardneck garlic and Polish White softneck tops are killed back to about one inch up from the mulch. Equally hardy, it seems.
We had the remains of a lettuce nursery bed, still holding surplus transplants from September sowings that we didn’t need for our greenhouse or hoophouse. After the 4F assault we still had life in the centers of the Winter Marvel, North Pole, Tango, Green Forest. Now only the Winter Marvel shows any signs of life. So that variety gets the prize for cold-tolerance here!
In the hoophouse, we covered all the beds with thick rowcover every night it looked like dropping below 10F inside. Almost everything survived – we only got some minor stem freezing on some turnips and Asian greens. We have been eating Pak Choy, Tokyo Bekana, Yukina Savoy, various turnips and their greens (Hakurei, White Egg, Oasis, Red Round), also plenty of lettuce leaves, radishes, scallions, and some spinach. We lost our second sowing of spinach in there to over watering and flooding, and we are really noticing the lack right now. We’re short on spinach. We have small amounts of mizuna, Ruby Streaks, Bright Lights chard, Bulls Blood beets to add to salad mixes, and Red Russian and White Russian kale growing slowly.
In January we have taken to sowing spinach, kale and collards in a hoophouse bed to transplant outdoors in early spring. We back this up with sowing some in flats if we don’t get good emergence for some reason. This year emergence is late. Is it just late, or is there a problem? We’re holding our breath for a few more days. . .
We are not the only people tracking the effects of the unusually cold weather. The February Growing for Market magazine opens with an article by Ben Hartman “Testing the Limits of Cold Tolerance”. He farms in Goshen, Indiana, using two double-layer plastic greenhouses heated to 30F (yes. I said heated!) and two unheated. They planted kale, carrots, spinach, salad greens and arugula in their greenhouses for winter harvest. Their outdoor temperatures fell to -16F on 1/6 and 1/7. I imagine they’ve had worse since. They used mid-weight rowcover over their beds. Ben reports that baby greens and young spinach survived, as did their rosemary and their 3 fig trees (all farmers deserve some thrills!). They lost baby salad greens that had already been cut previously (all those cut edges didn’t do well). Crops in the outer beds were lost. The tips of full-grown kale leaves froze, but the plants survived.
In their unheated, single-skin plastic hoophouses, the soil froze down to 4″. They used two layers of mid-weight rowcover suspended over the crops. Despite this cold, tiny salad greens less than 1″ tall survived. Spinach survived under just one layer of rowcover. The carrot tops froze and the roots may or may not be marketable. The (uncovered) fully mature kale looks dead. The mature salad with two layers of rowcover didn’t survive.
From this experience, Ben points out that salad greens and spinach less than 1″ tall are very cold-tolerant. Spinach and kale once larger, benefit from more protection than they got this time. Beware the outer beds!
My own article in this issue is about matching crop spacing with desired goals, such as maximum yield, optimum size, or convenience for cultivation.
Andrew Mefford has written some greenhouse tips for hoophouse growers, including tomato grafting, trellising. Chris Blanchard has written the second part of his piece on growing herbs – this is about harvest and maintenance. Erin Benzakain has undertaken a 59-variety trial of celosia.