Edible Perennials that you plant and harvest again and again are a rarity, but increasing in popularity in American gardens. Perennial Fruits are a dime a dozen, but vegetables - not so much. For the most part, perennial vegetables are lower maintenance than annuals.
They tend to have a higher nutritional value, are more eco-friendly than short lived annuals. They also require less resources as well as labor intensive maintenance. No persistent replanting season after season and no annual turning and tilling of the soil.
Once a perennial is established it is generally more drought resistant as well as resistant to disease and pests. When properly mulched, perennials actually enhance the soil structure, its porosity and water retention capacity benefit. The steady decomposition of foliage from autumn leaves and decaying roots puts back into the soil much of the nutrients that annuals simply leech out of it. Many perennial plants will also pull in atmospheric nitrogen and carbon that eventually finds its way into the surrounding soil.
Perennial Fruits and Vegetables can serve as hedgerow or border for existing gardens that will host your typical annual crops.
Some perennial vegetables will serve well when integrated within the garden and landscape as well. Some basic research into the art of companion planting is a good idea first.
Lovage for instance, a perennial veggie - herb can be intermingled with many other plants with the exception of beans and legumes. It is a large perennial, similar to celery in taste. Tarragon is another perennial Herb that is useful throughout the garden and kitchen. Asparagus, a perennial vegetable repels many plant pests and is helpful around most annuals but its growth is hampered by garlic, onions and related alliums.
Some Good Perennial Vegetables suited to Home Gardens.
Asparagus is an easily grown long lived perennial. Plants can be productive for over a decade. It takes 2 -3 years to establish an asparagus patch.
Cardoons are very similar to Globe Artichoke, but is in the sunflower family like Jerusalem Artichoke. It is grown primarily for its flower buds and stems both of which are edible. The buds are most commonly sought after. They are prepared and eaten in the same fashion as globe artichoke.
Rhubarb is a cool season, perennial plant that is very winter hardy and drought resistant . After its active growth season it becomes dormant and temperatures below 400 F are required to stimulate bud break and subsequent growth.
Horseradish is cold-hardy up to Zone 3, it's a perennial that grows best where there's ample cold weather to force dormancy. There are two primary varieties, common and bohemian horseradish.
Globe Artichokes are closely related to the thistle. The part we eat is from the immature flower bud. If the buds or "globes" are not harvested, six inch bluish thistle-like flower heads develop.
Jerusalem Artichoke also known as sunchoke is not related to true artichokes. It is in the sunflower family and closely resembles the common sunflowers. It is grown primarily for the tubers - healthy plants produce an average of 60 - 75 tubers per season.
Lovage is a perennial that grows up to 6 feet tall with lush green foliage and a spread of about 3 feet around. All parts of the plant are useful. The root, harvested in early Autumn is used as a vegetable. The leaves which can be harvested any time are added to salads, The Stems are like celery and best when eaten young.
Milk Thistle is not a true perennial, it is a biennial which takes 2 years to complete its growth cycle and is grown primarily for its seeds which contain extremely high concentrations of silymarin. Silymarin is beneficial to the liver and gall bladder and used to treat liver damage.
Sea Kale is a perennial that reaches roughly three feet in height with an equal girth. Its leaves are fleshy and smooth and resemble true kale. Sea Kale is hardy to zone 5 or colder- it is very frost tolerant. It is also grown as an annual in warmer regions.
Sorrel is not frost tolerant but is a perennial that can also be grown as an annual. Sorrel is grown for its tart tasting arrow-shaped leaves.
Watercress is a frost tolerant perennial, not truly a vegetable garden crop as it requires water - lot of it in fact it grows in water not soil
There are also many crops that can be grown as both annuals or perennials. Kale, Garlic, Malabar Spinach, Radicchio, Spinach are a few.
In the realm of Fruit Gardening, perennials are the rule as opposed to the exception. Most Berries will work well when integrated into standard vegetable gardens and landscapes See A-Z List Edible Berries