It's a typically bone-chilling winter day in southern New York State, with the mercury huddled at 20°F and six feet of crusty snow on the ground. Yet I've just picked some fresh Swiss chard for tonight's dinner! In another day or so, I'll gather some kale. I harvested tender, green broccoli a week ago, and a few days before that picked brussels sprouts.
No, I don't have a greenhouse, or even a cold frame. My crops are all grown in containers. I start them in late summer, let them reach maturity outdoors, then bring them inside when frost threatens.
The "green thumb bug" bit me a few years ago, when I first experimented with indoor plantings of tomatoes and cucumbers. Then in 1981 I rented a warehouse for my wholesale and mail-order spice business and decided to set up a rather ambitious container garden on the piece of asphalt pavement that came with the lease. During that summer my wife and I savored tomatoes, zucchini, peas, beans, kale, okra, chard, lettuce, and broccoli, all from my 200-square-foot plot of pots.
After the first hard frosts, I moved the remaining few containers of kale to the attic. A winter container garden wasn’t what I had in mind; I didn't really expect the plants to survive, because the single, east-facing window there receives only three to four hours of sunlight (when there is any) during the short days of fall and winter. Moreover, since I only use the warehouse for a few hours each week, I keep the temperature there below 50°F.
I was flabbergasted, therefore, at seeing how the kale flourished. My family ate one plant in January and another in February, and later that month I put the remaining two back outside. They seemed to almost spread their leaves to the cool late-winter sunshine and, in early April, yielded a bumper crop of greens.
With that experience behind me, I decided in the spring of 1983 to plant enough containers to provide my family with fresh vegetables at least once a week through the cold months and early spring. Although I concentrated on crops that would grow back after harvesting (chard, kale, and broccoli), I also planted brussels sprouts and cabbage (which store well) and two varieties of lettuce. All in all, I put in about 60 plants, staggering the sowings so that each vegetable would be fully grown by October 1.
We had an unusually mild fall. Jack Frost didn't move in until mid-December, but when he came around he seemed determined to make up for lost time! Like much of the rest of the country, we had the coldest Christmas on record. By then, of course, my plants were safely upstairs. I put shelves across the window and placed the best specimens on them, to make the most of whatever sun we were blessed with. I arranged the rest of the plants on the floor, where they had to settle for a thin ray of light that made a slow arc from 8:00 AM until noon. (During the late afternoon, I actually had to turn on a light to find anything in the 60-square-foot attic.)
Even so, our nine chard plants were very productive; we ate their greens once a week. By February, the leaves were small, but new growth continued. If anything, the baby shoots were more tender and tasty than the early pickings. The 30 regular kale plants and the five of the flowering types (which are as tasty and more colorful than the standard kind) also produced weekly harvests right up until I was able to pick outdoor crops in the early spring.
The broccoli, too, was a delightful surprise. Each of the ten plants produced scores of small but delectable sprouts. However, there weren't quite enough for a full meal at each picking, so this winter I'll plant more. The three cabbage plants weren't expected to grow inside, and they didn't. But one small head made some delicious cole slaw, and the other two, which were put outside in early spring, were ready to pick in just a few weeks. My five brussels sprout plants were harvested by late January.
Container Planting Tips
In the course of my experiments with winter container gardening, I've picked up some general knowledge that I would like to pass on.
Pots: Almost anything will do, from plastic milk containers to redwood planters, as long as they're big enough and have drainage holes in the bottom. However, I prefer plastic pots that are squared off at the bottom to allow the plant roots to spread. These are also lighter than clay pots (you may be moving them a lot), and they do a better job of reducing evaporation. Containers 8" to 11 " in diameter-which can be purchased from most garden supply stores for about $1.25 to $2.00 - proved to be adequate for all the types of produce I've grown so far.
Soil: I use regular potting soil, which costs about $3.00 for 40 pounds and can be used over and over again as long as a good fertilizer is applied at regular intervals. Each 11" pot for broccoli needs about 20 pounds of soil. The other plants can be grown in smaller containers. (You could also, of course, mix your own potting medium; recipes can be found in many garden books.)
Watering: When outside in the summer, container-grown plants generally need water at least once a day. I don't use saucers outdoors, but they're essential indoors to protect your floors. In winter, a soaking every week or so is usually enough, but do check your plants more often than that. If they feel dry, douse them. Mature vegetables tend to get thirsty, and they won't suffer if they have "wet feet."
Fertilizing: Generally speaking, you will have to feed your pot-grown vegetables more often than you would garden plants, because the frequent watering washes away the nutrients. If you use a fertilizer that must be scratched into the dirt, be careful not to damage your plants' roots. If they become exposed, sprinkle the fertilizer over the surface and then cover it with more potting soil. Feeding should be done every week or biweekly while the plants are outside, but it can be discontinued during the winter.
Sunlight: Leafy crops need at least six hours of sunlight in the summer, and flowering plants should have two or three hours more. If one location isn't bright enough, simply move the pots to follow the sun. Once they're mature and indoors, though, this factor isn't as critical. They'll pretty much make do with what's available until you're ready to harvest.
A Crop-by-Crop GuideSwiss Chard: