Perennials maintain the soil cover, soil structure and life within and have deeper root systems than annuals and thus provide soil stability and enhanced soil health. They can also tap available soil nutrients, enhance biodiversity, make more water available to plants, and capture and sequester carbon.
Common Perennial Vegetables
Artichokes, Asparagus, Florence Fennel, Garlic, Shallots, Watercress and Wild Rocket can all be grown as perennials in cool temperate climates, although not everyone will choose to grow them this way – when garlic is grown as a perennial, for example, the bulbs can become crowded and misshapen, which can make them less desirable from a commercial standpoint. Potatoes are also perennials, but for a number of reasons – one being that they won’t always survive UK winters in the ground – the roots are generally all lifted, and some are then later replanted. Something similar is true for Sweet Potatoes, although rather than replanting the roots themselves, they are generally propagated from slips. Tomatoes, Peppers (inc. Chili Peppers), and Aubergines, are also perennial, but tender, and will only survive under cover, not outdoors or in open ground.
Some vegetables that usually have an annual or biennial life-cycle, have close relatives that are perennial. In some cases, these relatives belong to the same species. Two of the best examples of this are the Brassicas and the Alliums.
Brassicas include cabbage, kale, broccoli, cauliflower, Brussels sprouts, kohl rabi, swedes, turnips, pak choi, among others. Of these, cabbage, broccoli, cauliflower, brussel sprouts, kohl rabi, and most kales, are actually members of the same botanical species, Brassica oleracea,. The wild cabbage from which these were developed – through selection for different traits over many generations – is often perennial, and a small handful of domesticated varieties have also retained this trait to different degrees.
Some examples include:
Taunton Deane: a hardy, vigorous perennial kale.
Daubenton – a slightly less hardy, bushy kale with tender leaves. There is also a variegated form available.
Purple Tree Collard: a very tall, long-lived Kale, with large leaves, with a stronger flavour than many kales. Some plants in the US are reputedly over 20 years old, however, it is only reliably hardy in the colder parts of UK.
9 Star Perennial Broccoli: actually more like a sprouting cauliflower.
There are other perennial varieties in circulation, and a number of amateur breeders are currently working with these to develop more.
Something similar happened with Onions and Leeks, which are both Alliums. White, Brown and Red onions, belong to the same species as shallots, namely Allium cepa, however, unlike the latter, the majority of onions sold today, and almost all Leeks (which belong to a different species, A. porrum), have had the perennial life-cycle of their ancestors gradually bred out of them.
In my own experience, some shop bought onions will grow as perennials. Beyond that, there are also several interesting perennial Onions. For example, the Potato Onions and Everlasting or Perutile Onions, both vareities of A. cepa,, and the Top-setting or Walking Onions (A. x proliferum).
The latter are thought to be a hybrid between A. cepa, and another species, sometimes grown as spring onions A. fistulosum. In the horticultural trade, these are known as Welsh or Bunching Onions.
They owe the latter name to the fact that they can form large bunches or clumps if left in place for a couple of years. Once established, some can be harvested from these clumps each year, leaving others to multiply, so there are some to harvest the following year..
There are also perennial Leeks – some heritage variety, such as St. Victor, will sometimes produces bulblets at the base, after they have flowered, which allow them to perennialize. There is also the Wild Leek, from which both common leeks and elephant garlic, were domesticated, A. ampeloprasum. One of the most commonly circulated is Babington’s Leek (A. ampeloprasum var. babingtonii)– it is slightly variable, but the flavour is usually stronger than other leeks, sometimes with garlic overtones, which make it less versatile. Some amateur breeders are working to develop further perennial leek varieties.
Throughout history, well over a hundred different species of Allium have been used for food. Below are some examples of those with which I have experience.
French Grey Shallots (A. oschaninii): or eschalot grise, are highly sought after in the restaurant trade for their rich flavour.
Garlic chives (A. tuberosum): the name says it all.
Wild Garlic (A. ursinum): edible bulbs, leaves, buds, flowers and immature seeds. Can tolerate shade. Very productive once established.
Rakkyo (A. chinensis): whole plant edible. Mild onion flavour. Often sold pickled in China.
Nodding Onion / Lady’s Leek (A. cernuum): whole plant has a strong onion flavour. Bulb, leaves and flowers all edible raw or cooked. Highly ornamental.
Three-Cornered Leek (A. triquetrum): and Few-Flowered Garlic (A. paradoxum) are both considered invasive. If they do invade, however, they are both excellent edibles.
Sand Leeks (A. scorodoprasum): also known as rocambole. bulbs taste of garlic, rest of plant more like onion, including the edible bulbils. Like leeks the leaves and stem need longer cooking to soften. Flower-stems can be used like garlic scapes.
Rosy Garlic (A. roseum): leaves have an onion / chive flavour. Bulbs are small, but can be eaten used like onions. Rosy-coloured flowers and bulbils also edible.
Golden Garlic (A. moly): Bulbs can be used as a garlic substitute. Leaves used for flavouring. Flower buds and Flowers edible.
Other Perennial Vegetables
Sea Kale (Crambe maritima): young blanched leaf-shoots delicious cooked, as are the florets (like broccoli), leaves cooked like cabbage (tougher so needs a bit longer), and edible roots, look a bit like horseradish, but tastes more like turnip.
Jerusalem Artichokes (Helianthus tuberosus) – roots delicious cooked or pickled / lacto-fermented. High in inulin, which can cause flatulence, painful in sensitive individuals. patches can be maintained, simply by leaving a few in the ground when harvesting.
Daylilies (Hemerocalis fulva): Young shoots and Flower buds used as cooked vegetables. Tubers cooked like potatoes. Petals are commonly dehydrated and used in soups in parts of Asia.
Good King Henry (Blitum bonus-henricus syn. Chenopodium bonus-henricus): a versatile, shade-tolerant, UK native perennial vegetable. Cooked leaves are a good substitute for spinach, raw they’re not that great. Immature flower stems are a delicious alternative to asparagus, and the seeds can be used like those its relative quinoa, after soaking to remove saponins (also required when processing quinoa).
Caucasian Spinach (Hablitzia tamnoides): shoots, leaves, vine tipes, and immature inflorescences edible. Tastes like spinach, but can live for 20 + years, and grows well in partial shade. Growing here with Herb Robert and Wood Avens.
Sea Beet (Beta vulgaris subsp. maritima): the wild progenitor of cultivated beets, chard and perpetual spinach. The roots are fibrous and generally not eaten. The young leaves are very good raw in salads, older ones cooked – a truely perpetual spinach.
Saltbush (Atriplex halimus): related to the annual vegetable known as Orache or Mountain Spinach (Atriplex hortensis), the leaves taste similar to spinach but with a natural saltiness (even when grown in non-saline soils).
Ground Elder (Aegopodium podagraria): Introduced by the Romans who consumed it as a vegetable. The leaves are edible raw or cooked, but are best when young and still glossy. Widespread, and considered a nuisance by many, as it is aggressively spreading, particularly on disturbed ground. However, it is also an excellent cut and come again perennial vegetable. There is also a variegated variety (pictured).
Alpine Bistort (Persicaria vivipara): edible roots (cooked) and bulbils (the little red things in my hand – on some plants they’re yellow). A nutty flavour.
Rock Samphire (Crithmum maritimum): the succulent leaves have a strong flavour that’s difficult to describe, and raw it can be a bit overwhelming if you use too much, but they’re delicious lightly cooked or pickled.
Black Salsify (Scorzonera hispanica): an excellent root vegetable, but eating this means digging the plant up and treating it more like an annual. They can also be grown as perennials for their tasty, mild-flavoured leaves. Flowers stems and unopened buds, can also be cooked like asparagus and make for very good eating!
Horseradish (Armoracia rusticana): for some purposes, the roots can be harvested from around the crown without digging up the whole plant, but well as a condiment from these, horseradish is also a good source of cooked greens. These aren’t spicy, but taste more like cabbage.
Edible Asters: at one point, all members of the genus Aster, but now divided into several genera. Several provide tasty cooked greens, including the following: Aster glehnii
Aster trifoliatus subsp. ageratoides
Kalimeris pinnatifida (syn. Aster iinumae)
Edible Hostas: the young shoots and flowers of several species of Hosta are eaten as a vegetable in parts of Asia. The young shoots (tightly curled up leaves) can be eaten cooked. The flowers have a sweet flavour and crisp texture
Chinese Toon (Toona sinensis): A tree from China. Young shoots and leaves, which have a thick, fleshy midrib, are a popular vegetable in parts of Asia. They have a rich savory flavour., with onion-like notes.
Sweet cicely (Myrrhis odorata): edible leaves, shoots, stems, flowers, roots and immature seeds, all of which have a sweet anise flavour which is strongest in the seeds.
Salad burnet (Poterium sanguisorba, syn. Sanguisorba minor): Cucumber flavoured leaves are delicious in salads.
Bladder campion / Carletti / Strigoli / Bubbolini, Sculpit / Stridolo (Silene vulgaris): young leaves delicious. Very popular in parts of Europe.
New Zealand Spinach (Tetragonia tetragonioides): edible leaves and shoot tips, best lightly cooked. Grows prolifically, but not fully hardy in colder parts of Britain and Ireland.
Small-leaved Linden / Lime (Tilia cordata): young leaves are delicious, tender and mild, with a slight sweetness. Excellent in salads. The buds as they begin to open can be used more like a vegetable.
Hops (Humulus lupulus): as well as being used to make beer, the female cones have been used to flavour foods. The young shoots are a popular wild-gathered vegetable in parts of Europe. At one point they were also successfully marketed in the US as a gourmet ingredient.
Alfalfa / Lucerne (Medicago sativa): the sprouted seed are a nice addition to salads and stir-fries, and the young shoots are good cooked.
Goji Berry (Lycium barbarum): together with its close relative, L. chinense, the plants are actually a popular leaf vegetable in parts of Asia.
Five-leaved Akebia (Akebia quinata): Fruit edible, but generally requires a pollination partner to set any. Young vine tips edible cooked, one of the Japanese Mountain Vegetables or Sansai.
Hopniss / American groundnut (Apios america): cooked tubers are delicious. Some people seem to be mildly allergic and experience digestive discomfort.
Aardaker / Tuberous Sweet Pea (Lathyrus tuberosus): tubers, sometimes called Earth Almonds, are delicious cooked. (second picture, unwashed tubers)
Tassel hyacinths (Leopoldia comosa): Bulbs used in Puglia, Italy – where they are known as Lampascioni (sometimes lampascione or lampagione), also parts of Greece I believe. A bit of a faff to prepare but very tasty.
Goatsbeard (Aruncus dioecious): Young shoots edible cooked. Edibility of mature plant parts unknown, as it accumulates cyanogenic glycosides (these are processed out of some foods, like Kidney beans, but levels in Aruncus may be too high).
Buck’s Horn Plantain (Plantago coronopous): young leaves edible raw or cooked, older ones best cooked. The young flower-stems can be used like miniature asparagus. The seeds are edible, and the seed husks can be used as a substitute for Psyllium husk (which are from related species).
Musk mallow (Malva moschata): Leaves edible raw or cooked. Flowers edible. Pink and White flowered forms exist.
Red Valerian (Centranthus ruber): edible leaves, good in salads, best in spring and winter. In summer, better if they’re grown in light shade with plenty of moisture, as they can become bitter if its too dry / hot. Red, Pink and White flowered forms all available.
- Eric Toensmeier on Perennial Vegetables – https://www.chelseagreen.com/2008/the-benefits-of-perennial-vegetables/
- Toensmeier, E., Furguson, R. Mehra, M., 2020. ‘Perennial vegetables: A neglected resource for biodiversity, carbon sequestration, and nutrition’ – https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0234611 –
- The introduction from Martin Crawford’s Growing Perennial Vegetables https://www.agroforestry.co.uk/wp-content/uploads/site-files-pdf/Perennial_vegetables.pdf