Pretty indoor primulas add colour with ease
INDOOR primulas were first grown in the 19th century for greenhouse display and as houseplants. They were grown in the big houses to provide colour in greenhouses and conservatories at a time of year when colour was scarce, and these are great fillers, relatively easy to grow and very colourful.
They have been produced commercially from that time and still appear on shop shelves, though not as often as formerly. They are usually quite cheap to buy, being disposable plants, discarded after flowering. They need only frost protection and a cool room in winter.
These primula species are native to the warmer parts of China where winter temperatures do not fall too low. Greenhouse primulas are closely related to primroses, both being part of the primula genus. The shape of the flowers is very similar to those of the native primrose, flat and with a narrow sunken centre.
Like the wild primulas, this kind keeps its leaves during winter and the leaves are much broader and more rounded than primroses. The plants are taller, usually about 45 centimetres tall. The flowers are carried on tall stems, quite slender, each flower held by a thin stem.
The flowers are held in clusters of 30 or more, the size of the cluster related to the size of plant. Big plants can produce several clusters of flowers, smaller plants just a couple of clusters.
The flower colours of the indoor primulas are usually pale mauve or pink, but there is a range of colours from pale pink or light lilac to deep red and purple.
The seeds are usually sold as mixed colours with far too many seeds. The seeds are small but germinate readily. They are sown in late spring for big plants or mid-summer for smaller ones to flower from late winter to late spring in a greenhouse or indoors, and they last for many weeks.
When the tiny seedlings are large enough to handle, they can be moved to individual cells in a cell-tray and later into small pots and potted up as necessary. Use half soil and half compost for potting , and liquid feed if necessary.
Keep the compost always just moist, allowing them to dry slightly between watering, but never too wet as this can cause rotting at the neck of the plant especially in winter. Watch for greenflies on the leaves. Give as much light as possible in winter.
Some people can get a skin reaction to touching the plants but modern varieties do not cause problems.