Coriander punch: Our gardening editor shares fresh ideas for common plants

While there may be little new under the sun, there are new ways – or ways new to us – to use many of our common plantsDahlias are not only a statement piece in a summer garden, but also a delightful flavour in tea.

Dahlia tubers for tea

When peak dahlia has been reached and passion for the flower spent, then what? Then you can eat them. Yes, the petals of this globally popular flower are edible. As are those gnarly-looking tuberous roots. Roast them. Boil them. Fry them. Or just chomp on them raw. Usually, as in their native Mexico, they are cooked much likea kūmara.

Although dahlias have been eaten for thousands of years in South America, their introduction in the 1800s to the West as an edible crop was a flop. Not for lack of trying. In the 1970s, William Mitchell, an American scientist, brought the world Tang, Jell-O, and Hot Rocks. He also had one notable failure – Dacopa, a coffee substitute made from roasted dahlia tubers, which sunk without trace.

Dahlia tubers are chocka with goodness – and flavour, which differ according to growing conditions and the variety. Alack, the names bear no relation to the taste. Do not expect the world’s most popular dahlia, ‘Café au Lait’ with its creamy rose-pink petals, to taste at all like a flat white. The flavours are more in celery, beetroot, spicy apple and carrot province, and become sweeter the longer they are in storage.

It is far cheaper to grow dahlias from seed than tubers. Pick a sunny spot with well-drained soil and sow seeds directly in spring or summer. Seedlings should appear in 10-14 days, with flowers within four months. Mound up tubers as they form with the earth as you would potatoes to encourage more growth. In autumn, harvest some for eating, leaving others to grow next year.

The Dahlia’s dried flowers can be used for tea throughout the year.

Use coriander berries for more flavour in your favourite dishes

Are you missing out on what many consider the best part of coriander and one of the great joys of growing the herb yourself? In some regions, green coriander seeds are known as berries and are prized for their intense and fresh flavour. However, such berries are rarely available for sale. Luckily, coriander is one of the easiest annual herbs to cultivate. Scatter some seeds where they are to grow, cover with soil and they’re away. In all but the coldest regions sow from August to May. As they tend to bolt in the heat, summer sowings are best made in light shade.

This native of southern Europe, northern Africa and south-west Asia is a fast grower so don’t miss the seeds, which form not long after the lacy white flowers. The green seeds need to be harvested at just the right time, usually about a fortnight after they have set, and when they are bright green, tender to the squeeze and still juicy. Then they can be used much as the rest of the plant is – in Indian and Mexican dishes for example. But cautiously, for they are more pungent. Grinding them with a pinch of salt in a mortar and pestle will help spread their flavour more evenly throughout a dish. Green seeds can be stored refrigerated in an airtight container for up to two weeks.

Coriander, aka cilantro, is a polarising herb. The aldehydes in the leaves can taste metallic or soapy to people sensitive to these compounds

Harvest supplejack berries and stems for protein and energy

Noted nowadays primarily for its ability to render our forests impenetrable, supplejack (kareao, Ripogonum scandens) was once considered a super-useful plant. It’s due for a return to favour, especially in gardens reaching for the wild, jungle vibe, or where gardeners seek a multi-purpose plant. Its strong, flexible vines can be woven into baskets and ladders, and used as rope or ties; while its edible red berries are often available nearly all year round (kererū and kākā love them). Also edible are the young shoots, which taste like beans. Early Europeans used the stems to make a Sarsaparilla-like drink, and the watery sap helped quench thirst in times of need.

Although it is difficult to obtain plants from nurseries, supplejack can be grown from seed. Plant in a shady spot and expect a slow start; it will remain a small shrub for about four years before beginning its ascent, as the stem tips spiral anti-clockwise up whatever they can find. Once established, the vines can grow up to five centimetres a day in summer and will travel across treetops and back down to form new roots.

The ripe supplejack berries aren’t just for our beloved Kererū

Add oxalis leaves to salads or soups for a tangly lemon flavour

Despite its pretty little trumpet-like flowers and because it can spread like wildfire, oxalis is a plant to fill many a gardener’s heart with dread. Every single one of its tiny bulblets is capable of very quickly multiplying into dozens more. But with a slight adjustment in perception, you may start to look kindly upon this maligned coloniser. The leaves of all green varieties of oxalis are edible and delicious; the oxalic acid in them imparts a tangy lemon flavour, which gives pep to any dish from salads to soups.

Because the leaves tend to wilt away to almost nothing and lose their beautiful bright green colour when cooked, generous quantities (at least a colander full) are needed to make this delicious and simple soup. First, saute a finely chopped onion in a dollop of oil or a knob of butter. Add the washed oxalis leaves and about 500ml of vegetable or chicken stock. Simmer for a few minutes, then blend before adding a similar amount of cream. Heat, add a soupcon of white pepper to taste and serve your soup with baguettes or other rustic bread.

The leaves of all green varieties of oxalis are edible. 

Perennial flax for oils and linens

Flowering so brightly and prettily in gardens now are several types of flax. Not our native flax (harakeke), so erroneously named by Captain Cook, but the real northern hemisphere flax.

These flaxes, used to make linen, are finer, more delicate plants. The most common plants here are the deep scarlet Algerian native annual Linum grandiflorum and the sky-blue perennial Linum perenne. The species most commonly used for linen and linseed oil is the closely related annual Linum usitatissimum with its pretty, light blue flowers.

Canterbury is New Zealand’s main region for growing L.usitatissimum – not for linen but for the oil. But whereas once its uses were predominantly industrial, now they are culinary. (Local gardeners are lucky to be able to obtain the residue as a straw for mulches.)

The Blue Linum perenne thrives in the sunshine and continues to flower throughout summer. 

The seeds of all three species are easily obtainable. All three love the sun. Should you wish to make your own fabric, the process is imminently doable. Just pull out the whole plant in autumn (the taller the plant, the longer the fibres), put it outside either in a stream or dew until the stalks fade to white, then beat and scrape these stalks until they resemble long fine hair. Next, it can be spun and woven. By my calculations, a square metre of plants should supply enough fibre for one tea towel.

Words: Mary Lovell-Smith

Additional photography Jeremy R Rolfe/nzpcn.org.nz

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