Sowing Primula seeds

Storing Your Seeds

If you do not wish to sow your seeds immediately on receipt, place the packets in a screw-topped jar or plastic box with a lid and store them in the fridge - not the freezer - until required. They can remain viable for several years.

Sow at the Right Time

The best time to sow primroses and auriculas is between February and April (late winter to midspring). A little frost can aid germination, but in very severe areas you should delay sowing to March or April. You will still get flowers in the following spring if you sow before the end of May. Sowings can be made in June or up to the end of July if it is really necessary, as long as you keep them cool and moist and they have time to develop before it gets too hot.

Asiatic Primula, Primula sieboldii and most of the other botanical species are cold-germinators and frost will help them to germinate. They are best sown from November to January (mid-autumn to mid-winter) and left outside, exposed to the fluctuating temperatures.

Autumn sowing

It is possible to sow in the autumn as long as your climate allows them a long enough growing season for the plants to establish before the frosts arrive. The later you leave it, the more difficult it is to bring small plants which are not well established through a winter season. It would be best to grow them on in pots over the winter before planting out in the spring.

Use an Appropriate Compost

Primula seedlings are very sensitive to concentrations of mineral salts found in fertilisers. If the mixture is too strong the seedlings may not grow at all, - or the young roots may be killed. Always use a seed compost and look for one which is as gritty and fibrous as possible. If it seems too fine you can mix it with some vermiculite, perlite, fine gravel or river sand. Primula roots need air to grow and develop. If the compost is too fine, a few waterings will drive all the air out.

Sow thinly

Primula seeds need light and air to germinate. Sow on the surface of the compost and do not cover with soil. Seeds which are slower to germinate (double primroses, hose-in-hose, jack-in-the-green, auriculas and most of the species) can be sown on a layer of vermiculite or very fine gravel over the compost. This will help keep them damp and also stop moss forming. Water them in with a fine rose.

Place a seed tray (perforated) of the same size over your sowings to protect the seed when left outdoors from birds or other animals and weigh it down with a stone.

Leave the lot in a shady place outdoors. Inspect regularly and water as necessary. Do not allow the compost to dry out. As soon as the seeds sprout remove the cover. Protect against slugs. Polyanthus and primroses usually germinate within three weeks. Auriculas are slower and Primula sieboldii may take up to six weeks.

Keep Sowings Cool and Moist

Ideal germination temperature is between 12 and 15°C (50-60°F). Lower temperatures do no harm, but anything over 18°C (65°F) is fatal. High temperatures inhibit germination.

Drying out - especially at the moment of germination -is usually fatal. Don't plant your seeds under glass, as temperatures rise too high on sunny days, - even in winter! NEVER use a heated propagator.

Don't Prick Out Too Soon

Primulas establish much faster if a good root system has developed before they are moved. Wait until you have at least four leaves before you prick out. A feed with a half-strength high potash fertiliser a week before pricking out helps.

Growing under lights

If you live in a northern zone that has very long and harsh winters it is possible to start Primula seed under lights to give them a longer time to establish before planting out. Sow as above in mid-winter keeping the temperature at around 12°C (about 55°F) and place under fluorescent lights. Keep the lights on for about 12-16 hrs a day. Keep the seed trays damp but well-ventilated, if possible watering from underneath once germinated. Treat with a very diluted fungicide if you notice signs of damping off.

Harden them off in spring by moving them into an unheated greenhouse for a few weeks. Prick them out into larger pots, place outside to establish before planting in the garden in early summer.