Forcing is a horticultural method used to bring flowering pot plants or cut flowers into bloom earlier than usual.
Who has never seen crocuses or hyacinths? But there is also a whole range of bulbous plants that flower in winter and create a real spring atmosphere at home. They include the plants described on this page, which can be forced indoors without any trouble.
Ipheion, Erythronium, Camassia and Iris reticulata flower in the garden only in late spring or early summer. Forcing, however, can make them flower earlier.
Erythronium dens-canis – dog's-tooth violet
This bulbous plant got its name because its bulbs resemble a dog's tooth. It grows mainly in North America, and also wild in the mountains of southern Europe, where it often grows alongside cyclamen.
In early spring the characteristic leaves appear, mottled in most species. When the temperature rises in April–May, flower buds form between the leaves.
After a short time beautiful small flowers appear, with backward-curving tepals in white, purplish-pink or red and white.
How long they last depends on the surrounding temperature. The lower the temperature, the longer the flowers stay on the plant.
Dog's-tooth violet grows mainly in deciduous woods and thickets. It therefore needs a partially shaded or shady position and moist, humus-rich, lime-free soil.
Care indoors
If you want flowering plants at home, dig up a few small bulbs in early spring on a warm day when the ground is not frozen. The best ones are those that have already formed small shoots. Plant the bulbs in a pot and stand it in a bright, warm place, but protected from strong sun.
After a few weeks the leaves appear first, followed by the flowers a week or two later.
Keep the plant in a cool place, and the flowers will last for about 3–4 weeks.
Camassia – quamash
Camassia is one of those plants that look especially striking when forced in a larger pot or bucket. The plant should not be disturbed too often. If you want to force it, choose one of the following two methods.
The first: every year in February, lift different bulbs from the ground and bring them indoors. Once they have been returned to the garden, leave them in peace for a few years.
The second: plant the bulbs in pots, plunge the pots in the garden and cover them with a layer of sand. Then lift the pot with the bulbs, bring it indoors, and later bury it in the garden again.
Indoors, the pot should be kept in a humid, warm place, away from strong sunlight.
Soon after the first green shoots appear, the plant forms a candle-like flower spike. Star-shaped flowers in various shades of blue are gathered at the top of a long flowering stem. Sometimes numerous offsets form on the mother bulb, so you will soon have a whole bouquet of flowers in the garden.
After flowering, Camassia needs dry soil. In the garden it should be protected from low temperatures in winter, especially in colder regions.
Iris reticulata – reticulated iris
This iris comes from Asia. Compared with other irises it is a real miniature, growing only 10–15 cm tall. It is one of the earliest spring plants, flowering in March and April.
It grows best in a sunny position in light, porous soil.
It does not need frost protection. The leaves appear very early, sometimes while the ground is still covered with snow. They are stiff and grass-like, clustered densely around the developing flower, which they protect. There are several varieties with flowers in various shades of blue.
Growing indoors
In autumn, plant a few bulbs in a pot filled with a mixture of soil and sand.
Bury the pot in the garden and leave it there until January or February. In early spring, lift the pot and bring it into a warm room. After a few weeks green shoots appear on the bulbs.
Water the bulbs regularly throughout. You can enjoy the first beautifully coloured flowers as early as the beginning of March.
Ipheion uniflorum – spring starflower
This wonderful bulbous plant from the semi-desert regions of Mexico and Guatemala was brought to Europe by Spanish conquistadors in 1593.
It is a rare small bulbous plant that grows 20–30 cm tall in the garden and produces pale blue, almost white flowers from April to May, depending on the position.
If the bulbs are planted close together, the thin grass-like leaves form a dense cushion.
Forcing indoors
Ipheion bulbs are planted very early, at the beginning of September. If you want the plant to flower indoors, plant the bulbs in pots and stand them in a cool greenhouse or conservatory.
Once the shoot tips appear on the bulbs, bring the pots indoors and place them in a sunny, bright spot.