Perfect for those who need to cut out sugar, stevia can easily be grown at home, says Marilyn Wightman.
The leaves of stevia are reputed to have the sweetest natural taste known. Pluck a fresh leaf of Stevia rebaudiana, bite into it and the sweet hit is instant. The human body is unable to process the sugar content of stevia, so eating it means blood-sugar levels are not raised and tooth decay is not an issue. It’s a favourite for diabetics, who can use this herb as a natural sweetener.
In Japan, stevia has been in commercial production since the 1950s. The Japanese government banned the use of some artificial sweeteners because of concerns about health risks, but the merits of stevia were quickly acknowledged and its uses accepted. Stevia accounts for over 40% of the non-sugar sweetener market in Japan, and is used in soy sauce, yoghurt, gum and frozen desserts as well as for sweetening pickles, seafood products and a wide range of low-calorie food items.
The herb originates from the highland areas of tropical Paraguay, but has readily adapted to the cooler, temperate climate of New Zealand. It grows in most areas of both North and South islands.
There are two varieties available. The narrow-leaf type is hardier, lasting for up to 10 years as a plant in the garden. While it is a prodigious, summer-flowering herb, it is infertile and does not produce seed. The broad-leaf variety grows readily from imported seed, but is not as robust. It is doing well if it grows beyond four years.
Stevia is a perennial herb. The leaves are about 1cm wide, 2cm-4cm long and oval in shape. Its small, starry, five-pointed daisy-shape flowers grow in clusters.
You can grow stevia in containers or in ground. In areas of high winter rainfall, however, ensure the plants have good drainage. A raised bed is the best place for stevia if soils are heavy and clay based.
In colder areas, the plant will be winter dormant as frosts burn off the top foliage. Retain this spoilt layer for protection until the plant begins growing new shoots in spring.
The clump slowly thickens at the base each year. When the plant is four years old, it can be dug up and split with a spade to form new plants if needed. This is best actioned in early summer.
In spring, give stevia its annual fertiliser application as a side-dressing. Watch out for snail and slug activity at this time, too, as the new shoots are targeted by these bugs, which seem to be the only botherers of this herb.
When new plants come away in spring they will reach 30cm high. After five years, the plant will be growing to 1m high each summer. Up to 50% can be cut off the top growth and harvested. The older the plant, the taller it will grow, yielding more and more foliage to harvest.
Cut the growth away in December and, if it comes away vigorously, then the herb can be cut again before autumn.
Spread harvested stevia onto sheets of clean newspaper and dry in a shaded, airy place. Turn once a day to aerate and assist drying, which takes up to two weeks.
Strip the leaves off and cut up the stalks. These can be ground into a powder or left whole. Place in a lidded container ready for use.
Stevia as a sugar substitute
Stevia can be used fresh or dried.
Baking: Make stevia tea and use it as the sugar and liquid (usually milk) content in a recipe. Add 2 tsp of powdered stevia (to every 250ml of water) to boiling water to infuse. Leave tea to cool before using. This will keep in the fridge for three days.
Non-sugar icing: Add 1 tsp of ground stevia leaf to low-fat cream cheese or yoghurt, and mix in the juice and zest of one lemon.
Drinks: Add 2 leaves or a pinch of ground stevia leaf to sweeten cold drinks and hot beverages.
With fruit: Add leaves to fruit that is being stewed, bottled or frozen.