Tulipa ‘Apricot Beauty’: Pre-chilling tulip bulbs will force them to flower early. Photograph: Gap Photos
Blushing-pink forced rhubarb heralds the start of the growing year, but it isn’t the only thing worth stirring into life early. Forcing with darkness and warmth makes everything sweeter and earlier. Bitter-tasting chlorophyll is held back due to the lack of light, and heat prompts new growth. Blanched vegetables have an unseasonal luminescence and buds burst early. Forcing awakens spring before her alarm sounds.
Amid the winter gloom, forced rhubarb sticks shine utterly pink and perfect. Tender and translucent – exposure to light makes rhubarb fibrous and acidic – they produce rosy mouthfuls sweet with the taste of an early spring.
Using an upturned bucket or forcer provides darkness and warmth, and coaxes rhubarb into early growth. In autumn, clear away the withered brown leaves, leaving the crown exposed. As the new shoots appear in winter, put the forcer over the whole plant. Leave for a few weeks. Once the stalks sprout, they grow very rapidly, often lifting the whole pot or bucket off the ground. Twist and pull to remove each long, pale stick, replacing the cover afterwards to encourage further growth. Forcing exhausts the plant’s energy, so remove the cover from April onwards to allow recuperation and don’t force the same plant again for a couple of years.
Varieties to try ‘Timperley Early’, thin, tender pink sticks early in the year; ‘Stockbridge Arrow’, modern variety with long, pale stems. Bred in Yorkshire’s rhubarb triangle.
Pre-chilling tulip bulbs will force them to flower early. Bulbs sold as “prepared” – commonly hyacinths – have been stored at low temperatures for several weeks so they bloom quickly once planted, but it is easy to force almost any ordinary bulb yourself. Tulips can be a blowsy, glamorous breath of spring from early February, if started now.
Choose early single, double or fosteriana types. Buy top-sized bulbs as early as possible and plant 10cm deep in pots of moist compost, their tips upwards. Wrap the whole pot in a plastic bag and place in a shed, cool cupboard or the bottom of a fridge, at 1-10C. Bud development can be impaired by ethylene, which is released if fruit is ripening nearby. The plastic bags prevent this, as well as keeping the compost moist. Leave in the cold for 10-12 weeks. The drop in temperature allows the tulip bud to fully develop inside the bulb and stimulates gibberellin, the hormone that pulls the leaf and stem towards the light. Darkness makes the roots grow.
When yellow shoots emerge, move the unwrapped pots into the warmth and light. Tulip flowers open fully in three to four weeks.
Varieties to try ‘Couleur Cardinal’, crimson and plum single; ‘Orange Emperor’, orange fosteriana type; ‘Ronaldo’, single early in rich damson; ‘Apricot Beauty’, softly flushed and shimmering silver; ‘Calgary’, pure white.
Witch hazel and forsythia
The buds of blossom on spring-flowering trees and shrubs develop in late autumn before the onset of winter dormancy. Vernalisation, the process by which a cold spell induces flowering when followed by warmth, means buds don’t break until temperatures rise in spring. By late December many trees and shrubs have had enough of a chill to allow them to be forced indoors. Bringing them into the warmth of the house makes the buds burst and bloom.
Choose a day after a cold snap when temperatures are above freezing. Cut 60cm lengths of witch hazel (Hamamelis × intermedia) and forsythia. Look for stems with swollen, plump buds. Flower buds will be larger and rounder than leaf buds. Submerge the whole branches in water indoors and leave for a few hours, even overnight. The next day, stand them upright in a bucket of fresh water. Keep the branches cool and out of direct sunlight. After two weeks when the buds show colour, move them into the light to bloom fully. From late January onwards, do the same with flowering fruits such as quince, cherry, crabapple and apple.
Varieties to try Hamamelis × intermedia ‘Jelena‘, sweetly scented coppery orange flowers; H. × intermedia ‘Diane’, red flowers with subtle fragrance; Forsythia × intermedia ‘Lynwood Variety’, vivid yellow blooms.
First early potatoes race to maturity in 10 weeks. With protection and a little warmth, a clutch of grubby seed potatoes will produce nutty-sweet, waxy tubers at a time when shops have only old spuds lifted last year and cold-stored. Potatoes need cool, light conditions, but sowing in pots with some gentle bottom heat forces the tubers to sprout early for fresh, pearly new potatoes, smelling of warm sweet earth.
Three-quarter fill 10-litre pots or empty compost bags with fresh compost. Turn bags inside out so the black outside absorbs more heat, and pierce for drainage. If you have a heated greenhouse, plant seed potatoes as soon as the days lengthen after the winter solstice, otherwise wait until February. Without chitting, sow two tubers rose end up in each pot and cover with 15cm of soil. Water well. As the shoots appear, earth up the haulms with more compost until the container is full. Flowers indicate the potatoes are swollen and ready.
Varieties to try ‘Rocket’ is a round, white new potato with a fine skin; ‘Epicure’, creamy and pear-shaped, has excellent flavour and is hardier than most; ‘Swift’, a stalwart of Scottish gardens, has a delicate skin with good disease resistance and smooth, sweet potatoes on compact plants, making it ideal for pots and under cloches.