I'd like to make the case for a wider uptake of perennial vegetables, many of which we may already be growing as ornamentals without even realising their edible attributes. Any plant that offers both good looks and good eating should definitely earn a place in the garden, particularly in bijou plots where space is always at a premium.
If you think about it, regularly digging over the soil is quite unnatural. It destroys a soil's aerated properties and exposes humus (its organic content) to the elements, releasing carbon into the atmosphere as it breaks down. Growing more perennials helps the humus content gradually build up undisturbed, while soil fungi will be able to lock up climate change-causing carbon dioxide. Soil drainage, its microbial balance and nutrient content will all improve. Once your crop is planted all you will need to do is keep on top of the initial flush of weeds and apply the occasional mulch of organic matter to the soil surface.
Consider also that most perennial crops have wider-spreading and deeper-seeking roots that draw on more of these soil nutrients. This means significantly more nutritious crops for us, with levels of minerals, vitamins and protein all typically higher than annual vegetables. And when many perennial 'vegetables' can be grown in the flower border you begin to see just how valuable they are.
Here are five easy-to-grow options that are both attractive and delicious. Please bear in mind that this really is just the tip of the iceberg – there are a LOT more and half the fun is researching (thoroughly and safely!) what other edibles are available to grow in your climate.
Daylilies (Hemerocallis fulva)
Common in Asian supermarkets, these beauties have a taste and texture that's a melting pot of beans, okra and asparagus. Plant them out into well-prepared soil in a sunny to part-shaded spot. Feed in summer with a high-potash feed and add a mulch in spring. It's the unopened buds that make the best eating, stir-fried with other veg. You could also try the opened flowers battered and fried.
Modern cultivars may be edible but the breeding process to produce blousier blooms may have had the unfortunate side effect of rendering some varieties mildly toxic. There's no guarantee which are edible, so err on the side of caution and seek out the original daylily species Hemerocallis fulva. This bears glorious orange star-shaped flowers and is widely naturalised throughout much of North America.
Bamboo (Phyllostachys dulcis and P. edulis)
Fresh bamboo shoots from the garden are a world apart from the canned option and will grow with pretty much no intervention. Set plants into a shaded corner of the garden and water well during dry spells. The shoots really benefit from a thick mulch of organic matter, helping to make them longer and more succulent. Cut the shoots when they are about 10cm (4in) high using sharp secateurs to sever the shoot a few inches below soil level. Remove the papery sheath to reveal the edible heart in the middle. There are more than 100 species with edible shoots, but there are also plenty that aren't edible – do your research first! Two types that definitely make good eating are Phyllostachys dulcis and P. edulis, both of which can also be crunched up raw.
Hosta/plantain lily (Hosta fluctuans 'Sagae')
Don't let the slugs have all the fun – get in on the action too! Young hosta leaves and shoots are a springtime delicacy much sought after in Japan. Give them a moist, shady position, keep the slugs away and your plants will thrive.
You can harvest as much as a third of the shoots produced in any given year without affecting the plant's vigour. Harvest just before the leaves unfold and enjoy them lightly blanched with a springtime salad. They taste a bit like a salty version of asparagus. The variety H. fluctuans 'Sagae', with its cream-margined glaucous leaves, was bred specifically for eating, so stick to this variety.
Dahlia (Dahlia pinnata)
Swap your spuds for the tubers of this popular garden flower. Originally brought over to the Old World from the Aztecs as an edible crop, the tubers are still widely eaten in Mexico. Plant tubers of the species Dahlia pinnata or the cultivar 'Yellow Gem' into improved soil after any risk of frost has passed. Other dahlias are reported as being edible but I personally can't vouch for this. Feed plants regularly and stake the lanky plants as they grow. Lift the tubers out when the plants die back in autumn. In warmer parts of the world you may get away with leaving a few of the tubers in the ground for next year's crop, otherwise save a few of the dug-up tubers for replanting in spring. The earthy-tasting tubers are delicious roasted or made into soup.
Good King Henry (Chenopodium bonus-henricus)
Why re-sow spinach every couple of months when this perennial equivalent is just as tasty? Grow several plants so that you can cut a few of the triangular-shaped leaves every few weeks without harming the plant. Cook the leaves as you would spinach. This easy-to-grow fleshy plant prefers a weed-free, fertile and sunny spot and will really come into its own from its second year.
A Word of Caution
Finally a few important words of caution. While many plants are perfectly edible (and delicious), others really aren’t! Modern breeding for ornamental value can compromise the safety of what was originally an edible plant. Always do your research before eating anything you’re unfamiliar with. Check the plant’s full name – variety as well. There are many books and websites of the subject, so read around and never rely solely on one source. Only grow new plants for eating once you’re completely sure of their safety and be certain they are reliably labelled in the plant nursery.