Primula: Greenhouse Plants
C – cool, minimum of 7°C (45°F)
This is a very versatile group of plants easily raised from seed which, apart fromsinensis (which needs darkness in which to germinate), needs light and a temperature of 13-15°C (55-60°F) for germination. All the greenhouse species mentioned here originate from China. P. obconica is perhaps the best known and is the one most likely to cause what is known as primula rash. I suffer from this and as a consequence am unlikely to grow and handle the plant.
This is a pity because there is now a wide range of flower colour and flowers which continue to open over a long period. My favourite (from a distance) is P. o. ‘Apple Blossom’. It is worth growing these on for a second year. P. malacoides is the very delicate species with lots of small flowers. Unfortunately, the plants are not worth keeping after flowering. I usually sow both these during late spring and summer. Another favourite is P. X kewensis which has bright yellow flowers and often farinose leaves and stems (that is they look as if they have been dusted with white powder). Sow this one during spring and the plants will flower virtually all year round and keep for at least two years. The secret with growing the plants is not to give them too large a pot at any time and be very careful not to Over-water which will lead to the plant collapsing. Scrupulous cleaning of plants, removing dead flowers and leaves will prolong their lives. Feeding the plants while in active growth will help them to extend the flowering period.