Most of the vegetable plants that are grown in New Hampshire gardens are annuals. Favorites like tomatoes, beans and cucumbers complete their entire life cycle in a single growing season and are killed by the first hard frost. There are few true perennial vegetable plants that come back year after year. Some of these are a little unusual, but they can be interesting and delicious additions to your harvest each season. If you’re tired of replanting every year, a perennial vegetable crop or two might make a nice addition to your garden.
Asparagus, one of the most beloved early spring vegetable crops, is actually a perennial that will produce spears for upwards of 10-15 years if well cared for. It can be grown from seed or one-year-old roots called crowns, purchased from garden supply stores or garden catalogs. Garden sites in full sun with deep, fertile soils are perfect for growing asparagus. The soil must be well-drained yet have good moisture-holding capacity.
Though asparagus can technically be grown in sandy soils, it will do much better in a rich loam. Planting asparagus in the north end of the garden is also a good idea because, once the harvest period is over, the remaining spears will grow into tall ferny leaves that can cast shade on other veggies.
It is important to wait to harvest asparagus for at least two years after planting if grown from crowns, and three years if grown from seed. If harvesting occurs when plants are too young, they won’t be strong enough to continue producing spears year after year. In their third year of growth, asparagus spears can be safely harvested for two to three weeks, and for six to eight weeks in every year following. After that amount of time has passed, allow the spears to grow into tall ferns. The ferns will replenish the roots and ensure a good harvest next spring.
Horseradish is an often overlooked hardy root crop that can be grown in northern gardens. Though not appropriate for fresh snacking, it can be ground or shredded and used to make spicy sauces and condiments such as cocktail sauce.
The best time to plant horseradish is in the spring, either from divisions from a fellow gardener, or purchased roots from a garden catalog. A little horseradish goes a long way, so look to buy the smallest quantity you can, which is usually five roots in a bundle.
Like most veggies, horseradish is most productive if it is grown in full sun in well-drained soils. When conditions are right, it may become aggressive and form a large colony, which is why many savvy gardeners plant it in contained beds.
Horseradish can be harvested as soon as the second year of growth. Aim to harvest in the fall after the first frost using a garden fork to gently lift the roots. In the process of digging, it is likely that a few root fragments will be left behind in the soil, which have the potential to grow into new plants the following season. For the best quality horseradish, plants should be divided in the spring every couple of years to keep the roots from getting too tough and woody.
Also known as “sunchokes,” Jerusalem artichokes are not actually artichokes at all. They are an herbaceous perennial in the sunflower family that produce edible underground tubers that look like a cross between a potato and ginger. The tubers can be eaten raw in salads or cooked like potatoes in any number of ways. They have a sweet, nutty flavor and are similar to water chestnuts.
Jerusalem artichokes are actually native to the central part of North America. They were once cultivated by Native Americans, who were responsible for introducing them to New England. Though they are native to the United States, Jerusalem artichokes have the potential to become weedy in New Hampshire.
They can spread by both seeds and roots and grow in just about any type of soil. “Volunteer” plants often show up in areas with moist soils, such as wetland margins. If you decide you’d like to try growing this vegetable crop, you may want to plant it in a contained garden bed to keep it from spreading beyond its welcome.
You can usually get a few Jerusalem artichoke divisions from another gardener, but it is also possible to buy them from some seed catalogs.
Jerusalem artichokes should be harvested in the fall. The tubers don’t develop until later in the summer and reach full size in the early fall. After the first hard frost they can be dug up with a garden fork.
Rhubarb is another tried and true vegetable crop that thrives throughout all of New Hampshire. It is beloved by many largely because it is one of the earliest spring crops, and it can be used to make delicious pies and preserves. The leaves are toxic, but the stalks are edible raw or cooked.
The best time to plant rhubarb is in the early spring as soon as the soil can be worked. You may be able to get a division from a friend, as rhubarb should be divided in the spring every few years. If not, you can usually buy a few crown divisions from a garden store or catalog.
Choose a planting site with full sun and rich, loamy soil. Rhubarb tends to be a heavy feeder, so adding some compost and fertilizer in the spring doesn’t hurt. Most gardeners like to plant rhubarb at the edge of the vegetable garden where it is out of the way and has plenty of room to grow undisturbed.
Ideally, wait to harvest rhubarb until the second growing season to allow the plants to become established. The stalks can be easily pulled or snapped from the base as soon as they reach full size.
Like asparagus, rhubarb should only be picked through the end of June. After that point, the leaves should be left alone to allow the plant to grow and store energy for next year’s crop. Removing flowering stalks will also promote root and shoot growth.
Though considered an herb by some people, chives are another perennial crop that can be incorporated into most gardens. They can be tucked into a quiet corner of the vegetable garden, or even planted in flower gardens, because the blooms are beautiful and are attractive to pollinators. Chives belong to the onion family, which explains their pungent odor and taste.
Two types of chives are commonly grown. Regular chives have round, hollow leaves and globe-like purple flowers. They are often used to garnish soups and salads or are chopped and added to sauces or dips.
Garlic chives are also popular and have thin, flat leaves with a mild garlic flavor. They are typically used in Asian cuisine to flavor dishes and are a nice addition to stir-fries.
Chives grow best when planted in full sun and in rich soil that is high in organic matter. They can be grown from seed or rooted plants. If starting from seed, only harvest individual leaves for the first two to three seasons. Once the plants are established and have grown into a good-sized clump, they can be sustainably harvested three or four times a year by cutting all the stems to the base.
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