If you’re lucky enough to have a greenhouse, it is possible to grow vegetables all year long. Some varieties are more successful than others, but many will thrive in the moderate temperatures of a heated greenhouse or the cool temperatures of an unheated greenhouse in a mild winter climate.

Vegetables growing in the greenhouse will exhibit painfully slow growth during the short days of late December and early January, but will continue to grow. Once daylight increases, or with the use of additional artificial lights, your vegetables will resume producing new crops.

They will never grow as quickly or as robustly as those grown outdoors during the summer growing season, but they will grow and produce a crop.

Tomatoes

A short-lived perennial in its native habitat in the tropics of the Americas, tomatoes Solanum lycopersicum var. can be brought into a greenhouse for the winter months. A tomato grown in a pot or hanging basket will adapt better to the greenhouse than one grown in the ground and dug up to be moved indoors.

Provide support for the plant as it continues to grow leaves and stems, and set fruit. Tomatoes should be grown in a warm greenhouse at temperatures between 68 and 78 degrees F. During the darkest days of winter surrounding the Solstice, your tomato will benefit from grow lights to increase both the light level and daily duration.

Peppers

Another short-lived perennial native to the tropical Americas, both sweet and hot peppers Capsicum annum var. adapt well to life in the greenhouse during winter months. As with tomatoes, the best results are achieved when peppers are already growing in containers rather than digging up plants from the garden bed.

Put the peppers in the hottest, sunniest part of the greenhouse and augment their sunlight with artificial grow lights during winter’s long days. When daylight reaches 12 hours daily in late winter, you can safely discontinue the artificial light exposure.

Lettuce and Salad Greens

During the spring and fall months, lettuce Latuca sativa var. and other salad greens are at their best in the garden. During the heat of summer they can also be grown successfully, provided they are grown in the shade of larger plants or beneath shade cloth.

In the greenhouse during winter, lettuce and salad greens will grow either in a cool or a moderately warm or hot greenhouse if placed next to the windows near the floor, where temperatures are cooler.

Lettuce and salad greens are fast-growing and should produce several crops successively over the winter months, especially if you harvest the large outer leaves and allow the smaller inner ones to continue growing.
By Sharon Sweeny