Edible perennials that can survive the winter chill

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For those folks anxious to get some early vegetables on the go, Mother Nature just gave us a less-than-subtle reminder that she’s the one in charge of garden timing.

The recent cold spell should also make us more aware than ever that all cool-loving veggies, like onions, peas and radishes, are best planted when daytime temperatures are consistently 10 C or higher. There are, however, a few edible perennials that can go in our gardens even before we hit that 10 C threshold.

Horseradish, a very hardy garden staple in the cruciferae family, has long been used to add spice to many of our foods. Native to Eastern Europe, Russia and Finland, early colonists brought it to the Americas, where it managed to escape out of those early gardens and into the wild, becoming a somewhat invasive intruder.

It’s a little more civilized today.

At this time of year, horseradish is available as root divisions. Plant them a foot apart with the thin end down and the top about three inches below the soil line. Planted now, they will mature by fall, at which time the outside roots can be harvested, leaving the centre root in place for continuous production. The most rapid growth takes place in late summer and once established, horseradish can be harvested year-round.

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To use them, grate the roots into white wine vinegar for immediate use, or if bottled and refrigerated, it will keep for weeks. For longer-term storage, grate and dry the roots into a powder before bottling.

Enjoyed fresh, however, is when horseradish is best and most pungent, adding a special zing to meats, like roast beef, and even to seafood sauces.

Related to sunflowers, the so-called Jerusalem artichoke (Helianthus tuberosus) is probably the least familiar perennial vegetable. Native to eastern North America, it has no relationship whatsoever with the actual globe artichokes we all know and love. Early North American explorers took some back to Europe in the 1600s. The French named them the ‘artichaut du Canada’. These very hardy, knobby little tubers spread rather quickly, to the point of being invasive. Planted about four inches deep, the tubers send up sunflower-like stalks that measure six-to-10 feet tall and produce three-inch flowers.

After about 100 days, the tubers can be harvested. In terms of preparation, they have many similarities to potatoes, but they should never be cooked too long for fear of making them too tough to eat. Most folks slice them finely into salads or use them as a garnish in clear soups. Boiled for about 15 minutes, they become quite tender and are especially nice served with an oil and vinegar dressing. At this stage, they can also be sauteed in butter for a wonderful treat. These tubers are starch-free, and because their carbohydrates don’t convert to sugar, they can be enjoyed by folks with diabetes.

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True globe artichokes can be started soon from seed, and they’ll still have time to produce beautiful, edible, flowering seed pods. These tender perennials (rated Zone 8) can be grown in colder climates (down to Zone 6) as long as they have good winter protection. Once established, they’ll produce year-after-year.

The ancient Romans were among the first to enjoy this unique edible thistle. After the collapse of the Roman Empire, the Medici family in Florence introduced these gourmet delicacies to the French.

Both French and Spanish explorers brought them to North America. If you have ever travelled through the agricultural areas between San Francisco and Santa Barbara, especially during September through to May, you’ll see hundreds of acres of artichokes under cultivation. They make quite a spectacular sight.

Most folks start with mature plants when the temperature warms up in mid-April to mid-May. Within one growing season, these large, three-to-four-foot plants will each produce three-to-five thistle-like heads that will be ready to harvest in late summer when they’re tight and plump. Boiled or steamed for about 45 minutes, they can be served hot or cold. The leaves, pulled off one at a time and dipped in a sauce or melted butter, are then eaten by pulling each leaf through your teeth to extract the delicious, pulpy contents. Once all the leaves have been enjoyed, scrape away the fuzzy centre and enjoy the heart of the artichoke with any number of herb sauces.

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In our area, once artichoke heads are harvested, cut the stalk down to about one foot, and as winter approaches, protect the plant well with a combination of mulch and evergreen branches. Always locate artichoke plants in the sunniest area of the garden, out of cold winter winds.

Now is the time to plant long-lived rhubarb, the most well-known and most popular perennial vegetable. Rhubarb can be purchased either as rhizome clumps or as started plants. Started plants will save at least one year in terms of when they can be harvested. Rhubarb needs space because one plant can grow about three feet across. Most folks plant a single clump, but for a larger family, three plants will usually suffice.

Some of the best rhubarb varieties are Canada Red, Victoria, Crimson Cherry, McDonald and Valentine Red. Younger, thinner stems can simply be chopped into small chunks, while older, thick stems may need to be peeled before cooking or steaming. Rhubarb is predominately used for desserts, such as rhubarb pie, which is a classic, or combined with a variety of berries to make great jams, jellies and fruit compotes.

Asparagus is a highly prized perennial vegetable. Although it takes three years from seed to come into production, its roots continue to produce for at least 15 years. Starting with established one- or two-year-old roots will save at least one year of growing time. ‘Mary Washington’ is a traditional old favourite. Newer hybrids, like ‘Jersey Knight’, produce larger crops of big, attractive green spears with purple bracts and tips. ‘Millennium’ is one of the most productive yet. The spears of ‘Sweet Purple’ have a 20 per cent higher sugar content and are usually eaten raw. ‘Rhapsody’ is a delicious white variety. Once established, the spears must be covered with soil to keep them pure white.

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Asparagus needs a sunny, well-draining location with slightly alkaline soil. Planting involves trenches dug four feet apart, 12 inches wide and 12-to-18 inches deep. Each trench bottom is filled with a mound of soil mixed with well-composted manure. The top of the mound should be three-to-four inches below ground level.

The roots are laid on top of the mound, pointing straight down, 18 inches apart and spread evenly on both sides. The trench is backfilled, leaving the tips of the asparagus just barely covered. Root growth begins almost immediately, although it will take a year for the roots to become well-established.

The second year after planting, harvest a few spears for up to six weeks. When the spears are six-to-eight inches high, cut them at a 45 degree angle about 1 1/2 inches below the soil line — be careful not to damage the crowns.

If any spears get away on you, let them develop into foliage. Once the spears become very thin, stop cutting. Let the plumes grow all summer. In colder parts of B.C., leave them standing to trap snow for better winter protection. In the Lower Mainland, cut the plumes off in September when the seed pods start to form and cover the roots with four inches of coarse manure.

All these edible perennials are a real treat in any garden, and as our growing season begins soon, try to find a home for some or all of them for years of enjoyment.