by Sally Morgan
Chicory (leaf chicory, Italian chicory, radicchio) Cichorium intybus A herbaceous perennial with blue flowers. It can be grown as a forage plant for livestock, but is more usually grown for its leaves, buds and roots. It is a useful plant, as its deep roots bring up minerals from deep in the ground. The leaves are used in salads while the roots can be used as a coffee substitute. It can be established from seed, planted out at a spacing of 20cm (8"). Plants need to be well watered in hot periods to prevent the leaves becoming bitter. The leaves are harvested by cutting them close to the base of the plant. Chicory is a hardy plant that can be sown late and harvested through winter. Plants can be forced by growing them in a dark place such as a cellar.
Garlic Allium sativum Garlic is usually grown as an annual, with the bulb planted in winter and harvested in summer. However, it can be grown like perennials. Simply leave some of the bulbs in the ground and they will come up again the following spring. Garlic likes full sun, and although it will grow well in most soils, it does not like heavy clay soils prone to waterlogging. I have a clump of garlic plants in the polytunnel that has survived for 5 years, and each year I harvest a few cloves. They selfseed too, providing me with seedlings for salads or for transplanting.
Giant butterbur (bog rhubarb, fuki, Japanese butterbur) Petasites japonicus A large plant with huge rounded leaves that resemble rhubarb. It needs boggy ground and is tolerant of shade, so it can be grown under trees, but it can be invasive. The edible stalks are eaten in the same way as rhubarb.
Good King Henry (poor man’s asparagus) Chenopodium bonus-henricus (also known as Blitum bonus-henricus) A useful, unfussy plant, growing to 60cm (2'). The leaves can be continually harvested, even through winter. They are bitter, so use salt to draw this out before cooking. Harvest the young spring shoots and cook like asparagus, and use the flower buds like broccoli.
Globe artichoke Cynara cardunculus Scolymus Group These big thistle-like plants are grown for their large flower buds, which are harvested before they open. Sow seeds in spring and transplant the young plants at a spacing of 60-90cm (24-36"). They grow well for a couple of years but then need to be divided to retain their vigour. In winter, mulch with straw or well-rotted manure to protect from frost.
Horseradish Armoracia rusticana Growers have a love–hate relationship with this plant! Be careful where you plant it, as once it’s in the ground its roots take hold and it’s almost impossible to get rid of. It is grown for its roots, which have a strong mustard flavour, but the leaves are edible too. Plant by digging a hole and backfill with compost. Place a root into the hole at an angle, cover with soil and then water.
Lovage Levisticum officinale A tall perennial herb, growing to 2m (6'6") or more with long, hollow stems. The young leaves can be used as a substitute for parsley or celery, but it’s got a more punchy flavour. It can be shredded and added to stews or scrambled eggs. It has medicinal value too. The large leaves die back and are replaced, so by clipping you get a steady supply of fresh leaves. The new stems are tender and can be steamed and served with chicken, while the taproots can be peeled and used like salsify. Harvest the seeds and substitute them for celery seed in pickles.
Perennial kale (everlasting kale) Brassica oleracea Ramosa Group There are various perennial kales, including my favourite, the Taunton Deane kale or cottager’s kale (pictured on page 80). This one grows to 1m (3') or more in height, growing for years to yield a supply of greens year-round. The deep roots bring up minerals from the subsoil, so the leaves are particularly nutritious. It’s an unusual plant as it doesn’t set seed, so it has to be propagated by taking cuttings. Simply take off the side shoots and pop into potting compost. A close relative is Daubenton’s perennial kale, which grows to about 70cm (28").
Rhubarb (Victoria rhubarb) Rheum x hybridum (also known as Rheum rhabarbarum) A familiar herbaceous plant with large leaves and fleshy-coloured petioles (stalks) that grow from thick rhizomes. It has a distinctive tart taste and is commonly used as a fruit, although it is a vegetable. It is an easy plant to grow and prefers free-draining rich soils in partial shade. It is usually established from crowns (rhizomes) in autumn and winter, at a spacing of 80-120cm (32-48") between plants. In summer, once the leaves have died back, mulch around the plant to conserve moisture and keep the weeds down, but do not cover the crown.
Salad burnet Sanguisorba minor An attractive clump-forming perennial with saw-edged leaves that have a cucumber-like flavour. It is also used as a medicinal herb. Can be grown from seed.
Sea kale Crambe maritima A maritime plant that grows wild along coasts, found in shingle banks. Another Victorian favourite, it is grown for its forced white stems, which are eaten from the middle of winter to early spring. The leaves can be harvested too and fried in olive oil. Sea kale can be established from seed in spring. It prefers a rich, well-drained soil in partial shade.
Skirret (perennial parsnip) Sium sisarum This was once eaten as a root across Europe in the Middle Ages, but it lost favour once the potato arrived. The skinny roots taste of mostly parsnip and carrot, with a hint of potato, and can be harvested all year. Grow from seed in spring and plant out in well-manured beds. By late summer the plants reach 1.5m (5') in height and have lots of small white flowers. It is best to allow them to grow in the first year and get established before taking a crop. The following year you will have lots of thin roots. Keep the plants well watered, otherwise the roots can be tough. You can propagate by dividing the roots.
Sweet cicely Myrrhis odorata This herbaceous perennial can grow to 2m (6'6") or more. It has feathery leaves and umbels of white flowers. The leaves have a strong smell of aniseed and are used as a herb. The roots and seeds are also edible.
Walking onion (Egyptian onion, tree onion) Allium cepa Proliferum Group This onion has chive-like leaves, which can be used like spring onions. Allow some to grow bulbils on the end of their leaves, which will bend to the ground and root, hence the term ‘walking’.
Welsh onion Allium fistulosum An evergreen, hardy, perennial onion that is ornamental as well as culinary. Despite its name, it originates from China. These green onions form bulbs similar to those of spring onions. The shoots die down in winter. They can be established from seed.
Winter savory Satureja montana An aromatic herb with dark green, narrow leaves and white flowers. It is grown as a companion plant around beans, as it deters mildew, aphids and weevils. It grows to about 50cm (20") and is a good border alternative to the dwarf box.
Welsh onions in flower. Remove the flower heads from young plants to encourage root growth.
The towering Taunton Deane kale, also known as cottager’s kale, is one of my favourite perennial vegetables.
Tubers and roots
Although not strictly perennials, there is a whole host of tubers that are useful and low maintenance. Many of these are from South America, the home of the potato.
The Chinese artichoke (Stachys affinis), despite its name, is not related to the globe artichoke (nor to the Jerusalem artichoke – see below). This is a much smaller plant than either, growing to about 60-70cm (24-28"). The tubers are tiny, crunchy with a nutty flavour, and can be eaten raw in salad or stir-fried. Plant out the tubers over winter and harvest in autumn.
The Jerusalem artichoke (Helianthus tuberosus) is among the most familiar of edible tubers. A relative of the sunflower, it grows up to 2.5m (8') in height, and a row of these plants can form a useful and attractive barrier on a windy site. The flowers are attractive to bees too. The tubers are dug up in autumn, the best selected for the next year’s crop and replanted, and the rest eaten. They are prone to falling over during windy weather towards the end of summer, so stake them before they get too large. Cut off the dying stems and leave the tubers in the ground until needed, as they do not store well.
These Jerusalem artichokes form a summer barrier in the vegetable plot.
Oca (Oxalis tuberosa) produces a small tuber that comes in various colours and is used just like a potato. The advan
tage of this easily grown ‘Inca’ crop is that it is blight-free. The tubers produce bright green clover-like leaves and attractive yellow flowers. However, the tubers only start to form in autumn and are harvested from mid winter to early spring. As the plants can be damaged by frost, care needs to be taken regarding where they are grown. The beds should be covered with fleece as soon as there is risk of frost, to extend the period of growth. Once the plants have completely died back, leave them for at least a week before you harvest, as the plant will continue to move food into the tubers as the stems die back. The tubers have a lemony taste and are cooked, unpeeled, like a potato. They suffer from few pests, although rabbits have a taste for the young growth.
Yacon (Smallanthus sonchifolius) is another South American plant. It grows to about 1m (3') high, with large, sunflower-like leaves. Plant out in spring after the risk of frost has passed, and harvest in early winter before any hard frosts. It produces two types of underground structures: large storage tubers that are very crisp and can be used raw in salads, and knobbly growing tips, which are removed along with the crown and overwintered in a frost-free place, rather like dahlia tubers.
Yacon has distinctive large leaves. Underground are the edible storage tubers and the smaller growing tips that are replanted in spring.
More exotic choices include the Chilean ulluco (Ullucus tuberosus) and the Peruvian ground apple or mashua (Tropaeolum tuberosum). The Chilean ulluco produces attractive multicoloured tubers that resemble sweets. These are planted in early spring and will create a low-growing spreading plant. Tubers are harvested in mid to late winter. They are susceptible to slugs and snails. The Peruvian ground apple is a South American perennial dating back 5,000 years or more, grown for its peppery tubers. It is easy to grow, and, though the shoot is not frost hardy, the tubers can survive in the ground to about -7°C (19°F). The high concentration of mustard oils in the tubers may account for its resistance to nematodes and other tuber pests. In its native area it is used as a companion plant to potato (see below), repelling the pests of the potato tubers, and has been found to have medicinal qualities too.
Companion planting
Companion planting is a form of polyculture – which, as the name suggests, means growing two or more plants together. Companion planting has a number of benefits, including deterring pests and disease, attracting predators or pollinators, or providing either nutrients, support or shelter.
Some companion plants are beneficial because of their strong smell, which either repels a pest or lures it away (this is often described as a push–pull strategy in farming). For example, leeks are often damaged by thrips, tiny insects that feed on plant juices, causing white spots on the leaves. This is a tricky pest to control, as it hides between the sheaths of the leek leaves. Planting a row of lavender plants near the vegetable beds has been found to lure the thrips away from the leek. Brassicas can gain protection from pungent plants such as the tobacco plant (Nicotiana tabacum), Artemisia species and hyssop (Hyssopus officinalis), as the female cabbage white butterfly finds the leaves of brassicas through smell.
Gardening books have long recommended that carrots should be grown with members of the onion family, as the pungent smell of onion helps to confuse the carrot root fly, which finds carrots by smell, but trials by Charles Dowding and other gardeners have found no benefit. It is better to net the plants or, since the female carrot flies are low-flying, surround the plants with 60cm (2')-high barriers to keep the egg-laying females away.
Tall plants such as sweetcorn and sunflowers (Helianthus annuus) can provide shade for spinach and lettuce, or support for climbing French beans, while deep-rooted plants such as com-frey draw up minerals from deep in the ground, which are then incorporated into the topsoil through their leaf litter, to the benefit of plants growing around them. Equally, there are some pairings which should be avoided, such as legumes and onions. Onions exude substances from their roots which adversely affect the nitrogen-fixing bacteria found in root nodules of legumes.
The classic ‘three sisters’ combination of sweetcorn, squash and French beans.
Pollinating partnerships
Plants that attract pollinating insects are particularly beneficial, especially if you are growing fruit trees. Some partnerships to consider include a row of French marigolds by runner beans; sweet peas (Lathyrus odoratus) close to courgettes; and lavender planted near fruit trees. Remember to draw pollinators into your polytunnel to pollinate your early crops such as courgettes and broad beans, by planting marigolds (French or calendula) and early-flowering salvias.
A row of French marigolds has been sown beside these runner beans to attract pollinators and predators of pests.
The following are some of the most important companion plants, and should be included in the plot wherever possible.
Basil is often growing in polytunnels alongside tomatoes. There is conflicting opinion as to whether its pungent smell repels or lures whitefly and aphids, but most are in agreement that this is a beneficial partnership. Basil is also believed to boost the growth of peppers and aubergines.
Bee balm or bergamot (Monarda didyma) can be grown near tomatoes to improve their growth and flavour. It is attractive to pollinators.
Calendula or pot marigolds (Calendula officinalis) have bright flowers that attract many predatory insects, such as hoverflies and lacewings.
Chives have leaves with a pungent smell from the presence of sulphur-based compounds, and this deters many insect pests.
Dill has yellow flowers that attract hoverflies, and also parasitic wasps that parasitize the larvae of cabbage pests.
French marigolds (Tagetes patula) are essential plants in the veg plot and polytunnel. Their pungent smell deters whitefly and aphids, benefitting tomatoes. Their roots exude substances that help to control harmful nematodes in the soil around roots of melons and tomatoes, and act against eelworms, which damage potatoes.
French marigolds are key companion plants.
Mexican marigolds (Tagetes minuta) are useful plants, but they are tall. Their main use is as a bed clearer, as their roots exude an allopathic substance which inhibits the roots of other plants. Mexican marigold has been found to be effective in clearing ground of pernicious weeds such as ground elder and bindweed. The roots are said to have insecticidal, nematicidal, antibacterial and fungicidal effects.
Mint is said to improve the growth of tomatoes and cabbage. There are various mints, and their aromas deter cabbage white butterflies, ants, flea beetles and aphids. Mint is an invasive plant, so it might be grown in its own patch and the leaves harvested and used as a mulch around vegetable plants. The flowers of the mint attract predatory insects such as hoverflies.
Nasturtiums (Tropaeolum majus) are grown as a lure for white butterflies, drawing them away from brassicas. The plants secrete a mustard oil that attracts the insects. Nasturtiums will also draw blackfly away from broad beans and French beans, and if grown in the polytunnel they lure insect pests away from tomatoes and cucumbers. Nasturtiums planted around the base of fruit trees also help to repel bugs such as aphids and scale insects.
Poached egg plants (Limnanthes douglassi) produce masses of open flowers that attract predatory insects such as ladybirds and hoverflies. Grow them around broad beans and other legumes to give them protection from aphids.
Radish can be grown between rows of brassicas and spinach to lure away the flea beetle. You still get a crop of radishes, as their roots are unaffected by the beetle.
Bug Housing
Another way to attract beneficial insects and other minibeasts into the plot is to build a bug house. This can be made from structures such as old pallets, stuffed with all sorts of materials such as bamboo canes, broken pipework, tiles, clay pots or fleece.
Place your bug house in a sheltered and sunny spot, out of the prevailing wind.
Extending the season
In a temperate climate, you can gain many extra weeks of harvesting by means of a polytunnel or greenhou
se, cold frames or hot beds.
The warmth of the polytunnel allows for early sowing of half-hardy crops.
All-year crops in the polytunnel
Because of its large size, a polytunnel can provide you with a whole winter growing season, so you can have salads and other crops all year round. You can keep crops such as brassicas, spinach, Swiss chard and beets going through the winter, and also get an early start with seeds in late winter and early spring. But polytunnels are not frost-free environments, so many growers put up a secondary cloche of bubble wrap inside for sensitive plants, or block off a section of the tunnel which can then be heated. Heating can be expensive, but you can help to keep the ambient temperature above freezing by filling large plastic containers or dustbins with water, to act as heat stores. Or fill them with fresh manure and green-waste materials, which will generate valuable heat as they decompose.
In late winter I empty the plastic compost bin and fill it with fresh manure from the chicken houses. Temperatures inside the bin soon soar to 40°C (104°F).
See Chapter 1 (page 28) for a discussion of the options when setting up a new polytunnel.
Polytunnel planning
Just as with your vegetable beds, it’s important to plan the layout of your polytunnel to make best use of the space. With wider tunnels you may want two paths running the length of the tunnel, each wide enough for a wheelbarrow. I cover my paths with ground-cover fabric, but you could just as easily have an uncovered path. You can build raised beds too.