Grow Your Greens

by Harold Schrock | Jun 1, 2024 | 0 comments

What would life be like without salads? A bit boring, wouldn’t it? Have you thanked God for leafy greens lately? Of course, salads include a lot of variety. Not all salads have a leafy green base. Not every individual enjoys spinach and arugula, but I think most of us can agree that salad forms an interesting and important part of a wonderful omnivorous diet.

Leafy greens play an important part in many gardens, but they don’t generally get the respect of something like tomatoes or cucumbers. For many people, “salad greens” brings to mind a head of iceberg lettuce, or, for the more culinary adventurous, some leaf lettuce or maybe a bit of spinach. While these are a good start, there are a lot more adventures to be had with leafy greens in the garden and on the table.

Leafy greens will grow for fresh harvest when nothing else will grow. Since I live in upstate New York, this fact keeps me excited about leafy greens every year. If you have a greenhouse or walk-in high tunnel, you can have fresh-cut greens all winter long. Of course, you have to think beyond lettuce to accomplish a steady winter harvest. The crops hardy enough to survive single-digit temperatures will be things like spinach, arugula, and various Asian-type greens. All these crops are known for stronger flavors and may not appeal to people who have a preference for mild-flavored foods. If you fit this category, I have news for you. You can’t judge winter-harvested vegetables by the flavor they have in May or June. Winter-harvested greens are much sweeter and milder than their early-summer cousins.

Let’s explore what a whole year’s supply of greens might look like. I am writing from the perspective of the upper half of the US from about Tennessee and north, including southern Canada. In the southern end of this range, as well as farther south, it’s actually harder to grow greens year around than it is in the north. It’s harder to produce good greens in heat than it is in cold.

To grow a year-long supply of leafy greens requires a greenhouse large enough to walk around in. During the colder part of winter, you will need two layers of protection. Inside the greenhouse, cover the growing beds with wire hoops and woven or spun bond row cover. This is especially important in the northern end of our range. Farther south, one layer, even hot-bed-style low covers may be enough protection.

One thing to keep in mind when designing a winter growing system is that generally the smaller the protection, the harder it is to regulate temperature. A small hotbed will get colder at night and rapidly warm up to dangerous temperatures on sunny days.

Another thing to build in wherever practical is portability. In many areas, minerals in irrigation water and fertilizer products tend to build up in a greenhouse system where no rainfall leeches them away. Having the ability to move your greenhouse to a fresh location can be very beneficial. For this reason, I recommend building all greenhouses intended for soil-based growing with a structural bottom rail. A home-gardener greenhouse of 15′ x 20′ (5 x 6 m) or similar size can be picked up with the help of some friends and carried to a new site. There are systems of rails and trolleys to do the same thing with commercial-size greenhouses. In either case, anchoring is very important. A greenhouse can readily turn into a box kite. Typically, either strong stakes or screw-in ground anchors are used.

All sowing for a winter harvest is done between August and November, with the bulk of it in September and October. Crops suitable for all-winter harvest include arugula, beet greens, chard, spinach, turnip greens, green onions, some varieties of lettuce, and numerous varieties of Asian-type greens. Also carrots can be planted in July or early August for winter harvest.

Another benefit of the movable greenhouse is that all these things can be planted out-of-doors and will grow just fine until sometime in October or November. This allows you to use your greenhouse for heat-loving summer annuals such as tomatoes, peppers, and cucumbers until mid-fall, and then move it overtop of your established greens and be ready to go for the winter.

Many of the listed greens are cut-and-grow-again types that you can harvest multiple times as they slowly grow throughout the winter. Starting sometime in February, you can do some additional sowings of quick-growing greens, renovating beds that are beginning to fail. In March or April, as soon as the soil is dry enough to work outdoors, sow additional greens and cover them with hoops and a single layer of fabric row cover. Head lettuce can also be started in the greenhouse at this time and transplanted out as soon as danger of hard freezes is past. By getting your first outdoor sowing of greens started early under row cover, you can use your greenhouse to get a head start with early-planted warm-season crops.

Maintaining greens production throughout the summer requires multiple plantings of different types of greens. Many of the Asian greens are less heat-sensitive than lettuce, but their flavors do tend to get stronger in warm weather. I have utilized a shade cloth frame over plantings of leaf lettuce with very good results. Keeping the plantings moist also helps to prevent breakdown and over-maturity in hot weather.

The whole system I described above may sound a bit intense, and I agree that it is not for everyone. Some people don’t enjoy growing produce well enough that they want to garden year round. But for many of us, to be able to walk out through the snow on our way to harvest some fresh food is a wonderful thing.

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