Growing Primula from Seed

by Claire Cockcroft

(Taken from Primroses Quarterly, Spring 2007 Vol. 65 No. 2, pages 8-10)

Growing primulas from seed is rewarding for several reasons: seed packets are an economical way to produce a large number of plants; seeds are often the only way to acquire some primula species; and finally, seed growing can be quite dramatic. Yes, dramatic! Think of the joy of watching your seedlings come up, the wrath toward pests that tromp through your precious seed pots, the anguish accompanying the dreaded words “damping off”, the triumph of seeing mature plants that you’ve grown from tiny seeds!


I have been growing primula species from seed for the past 15 years. My methods have evolved over time as I learned techniques shared by other growers. Luckily, I started with Primula japonica, a candelabra that is an easy and reliable grower. In general, though, most primulas are relatively easy to germinate if the seed is fresh or has been stored with care. Society seed exchanges are excellent sources of Primula species and usually ship seeds to their members in early January. I sow primula seed as soon as it is received to take advantage of the cool, damp weather here in the Pacific Northwest. Any seeds received after the first of March are stored for fall sowing in screw-topped jars in a refrigerator (not freezer) to keep them cool and dry.

The very first step I take in sowing seeds is not to prepare pots or sprinkle seed. It is to record what I am planting plus the seed source and other pertinent details and to make my labels. I use a computer and spreadsheet for this, as they suit my needs well. In the spreadsheet, I include a plant’s cultural requirements as an easy reference for when it comes time to pot up or plant out. In the process, I also gain some hints that may help me grow the primulas on more successfully. I prepare my plant labels using the information from the spreadsheet. As I often sow more than a hundred pots of seed in a year, making plant labels is a tedious task. Nowadays I automate the process by using clear laser address labels on plastic plant markers. Each label has the primula name, source, brief description, some cryptic cultural notes, and the date sown.

 

Photo: Claire Cockcroft

 

I use 4”Wx4”D plastic pots; these square pots fit nicely into nursery flats and don’t dry out quickly. An added bonus is that the pots are big enough to accommodate many primulas for a full growing season, allowing me to delay repotting until the young plants are larger and more robust. I use a commercial growing medium. Of the many seed and growing mixes available, look for ones that are loose and quick-draining and avoid ones that are heavily fertilized. If additional fertilizer is needed because you delay repotting, you can easily meet theprimulas’ needs by using a dilute solution of liquid fertilizer during the growing season.

I like to prepare all the seed pots at the same time, filling the pots within a half-inch of the rim and tamping the mix down lightly. Primula seed needs light to germinate, so I top each pot with a thin layer of coarse granite grit before sowing the seed. The grit serves several purposes: it keeps the planting mix damp and in place; I’ve read it can reflect light onto the seeds; and it seems to slightly inhibit the growth of moss. You can presoak the planting medium by placing the prepared pots in a shallow tray and watering them from the bottom. I will admit I don’t always take the time to do this.