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Winter Gardening
By Ed Perkins

Winter Gardening January 2003
Long version for Oeffa web site
By Ed Perkins, Oeffa member and market gardener in Athens Co.

Gardening does not have to end with the falling leaves of autumn. Many of the leafy greens can be produced all winter. And you do not need an expensive heated greenhouse. Simple, homemade covers heated only by the sun can keep you in fresh greens all winter.

About 8 years ago the Athens Farmers market started staying open all winter. This provided the incentive for several of us to find ways to have some fresh produce for the winter market. Here is the system I came up with.

The primary leafy greens I am growing through the winter are spinach, leaf lettuce, arugula, kale and chard. Other good candidates include the many brassica greens such as tatsoi, pac choi and mizuna. The winter crops are first established in the garden in the fall, with the covers put on later when it turns cold. Spinach and arugula are the coldest hardy and produce the best. Lettuce and chard are less hardy and produce less. They all bolt at different times in the spring. I plant new crops as early in the spring as possible to replace the depleted and bolting winter crops.

I use permanent raised beds for the winter crops because of their better drainage and warming properties. Depending on the crop I plant from mid-August into October. Of course my planting dates here in southern Ohio may not suite other locations. You will have to experiment to get the best dates for your location. Even then finding the perfect planting dates is impossible because of weather variations from year to year. A warm fall will bring the crops on sooner, a cool one much later.

Since these are all cool weather crops getting them started in the heat of August and September can be difficult. I start all the crops except spinach in flats that can be placed in a cool, dark place until germination. Set the transplants out closer than you normally would since winter growth is so slow. Spinach does not transplant well so I direct seed, covering with mulch and sometimes shade cloth to get it started. Of course watering well is essential.

There are numerous ways to cover the crops for the winter. I use temporary structures that are set up over the crops when it turns cold and taken down in the spring. I prefer this system to a permanent greenhouse for two reasons. With movable structures the crops can be rotated to different parts of the garden every year. The plastic sheeting is taken down and put away thus protecting it from the summer's more intense UV radiation and so prolonging its useful life.

I am using two types of covers that I call high and low tunnels. The low tunnels cover one 3 feet wide bed. Hoops just high enough to cover the crops are stuck in the ground at about 3 feet intervals, plastic sheets pulled over it and held down along the edges with rocks. It takes a lot to hold the plastic down during winter storms. It is important that the plastic does not touch the crop leaves, which are damaged if contacting the cover in freezing weather. At first I used wire for hoops but the weight of the snow caused the tunnel to collapse. I now use half inch PVC plastic pipe which holds up well in the snow. Half-inch metal conduit would probably also do the job. I use two sheets of plastic over lettuce beds but can get away with one sheet over spinach which is hardier than lettuce.

The high tunnels cover two beds with the path in between and are high enough to go in bending over. They require a little more substantial support. The hoops consist of three quarter inch metal conduit and are 15 feet long before being bent with a pipe bender to fit over the two beds. I drive short re-bar stakes into the ground along the edges of the beds to be covered. The hoops then go over the stakes to hold them in place. They are five feet apart. I attach ridgepoles to the peaks of all the hoops plus end poles connecting each end to the ground. It makes a sturdy structure. The one layer of 20 feet wide plastic sheeting is then pulled over the framework and held down with large rocks and cement blocks. Again it takes a lot. This year I am trying a rope going back and forth over the top of the structure and held down by stakes along the sides. Maybe this could cut down on the amount of blocks and rocks required to hold the plastic down. For added protection inside the tunnel I put two layers of floating row cover over each bed supported by low wire hoops. These inner covers are taken off on warm and sunny days.

A word about coverings. At first I used 4-mil plastic sheeting from local stores for the low tunnels. It is cheap but does not last very long, becoming brittle and tearing in only a few years. I am switching over to authentic greenhouse 6 mil poly films. It is a lot more expensive but hopefully will last longer, especially since it is taken down in the summer.

Of course the winter weeds (chickweed, henbit, winter cress) grow just as well as the wintergreens so weeding is necessary. You can even eat some of the weeds in your winter salad. Neither is the winter garden free of insect and animal pests. Slugs love it under the winter covers. Hand picking is the best remedy. Watch out for aphids on kale and other brassicas. I use insecticidal soap in a small spray bottle to keep them in check. The first years I did winter gardening the spinach plants kept disappearing. I finally figured out it was voles (like mice but with short tails) tunneling under the spinach plants, eating off the taproots leaving the leaves wilting on the surface. How maddening. After several failed attempts I found mousetraps, baited with sweet potato and placed at the holes they left in place of spinach plants, would catch the little devils. They only like taproots like spinach, so lettuce with a fibrous root system is spared. One must be vigilant and place the traps as soon as damage appears.

Now the best part - harvesting. The most important thing to know is don't harvest if the leaves are frozen. They will turn to mush when they thaw, as I found out the first time I made that mistake. With the low tunnels, of course, the covering must be taken off. So if it is freezing as you pick, better do it quickly and get the covering back on. The big advantage of the higher tunnel is you can go under it to harvest. It does get to be a pain moving all those rocks getting into the low tunnels.

Here is some specific crop information. Spinach the main variety I have been using is Tyee. This year I also planted a bed of Giant Winter from Fedco and I am keeping track of the amounts of each harvested. So far Giant Winter has produced the best but must wait for the end of winter to determine which does best. I made a mid-September planting which was ready in pick in mid-November and a mid-October planting to over winter for early spring harvest.

Arugula was planted in flats in late September. But because of the cool fall it was not ready yet as of mid January. I should have planted earlier. Better to have something come on too early than too late.

Kale and chard must be started earlier during the mid to end of August. I use Konserva kale and Fordhook chard, although other varieties would probably do just as well. Neither produces too great in a cold winter but will pick up as it warms up in the spring.

Lettuce is the least hardy of the crops I have grown in the winter. It is prone to freeze damage and rotting out, but even so is worth growing. I have two types going this winter a planting to be picked as head lettuce and another for salad mix. The head lettuce varieties are Red Sails, Simpson Elite, and romaine. I made three planting end of August for harvest in December to January, mid September planting for February harvest and a mid October planting for early spring.

For salad mix I grow different varieties of leaf lettuce including red and green oak leaf, red and green romaine, Sierra, Royal Oak and Bronze Arrow. I made one big planting in mid September but should have planted earlier. It is not ready as of mid January. When harvesting I pick the outer leaves only so that it can grow back. Head lettuce is cut at ground level and will not grow back.

So that's my system. The bottom line is it all depends on the weather.