I am a home gardener and do not have a greenhouse. For the first time I have bought specialty primula seeds, see list below of genus species. The packages come with very little instructions other than to keep cool and cover lightly. I was hoping to direct seed them into my garden this spring. I would appreciate any information you have to share with me regarding successfully growing them. I would be happy if I got just a few plants from each pack.
Primula florindae Orange
Primula denticulata best blend
Primula japonica mix
Hello, gardener – As you may be aware, Primula is a large genus of herbaceous perennials with over 400 species. They are native to many locations in Asia and Europe. None are native to North America but many of the cool climate species can be grown successfully here. Note that Barnhaven, a nursery specializing in primroses in France recommends that seed you are not going to plant right away should be stored in the refrigerator in a glass jar to maintain its viability.
I found an excellent article in Fine Gardening magazine from a gardener in Connecticut on growing primulas (link below). The author mentions Primula denticulata and Primula japonica among her most dependable varieties and specifically mentions Primula japonica as easy to grow from seed. You have indicated that you want to direct sow the seed in your garden. I was unable to find any source with instructions for direct sowing. I suggest that the method presented in the article is a better choice and now is a good time to get your seeds started. The author advises planting the seed anytime between January and March in small pots filled with a moist seed-starting mix and covering lightly with vermiculite then placing the pots outdoors in a protected spot. Once the seeds germinate, it will be important to keep them well watered from the bottom until the true leaves, that is, the second set of leaves appear at which point they can be transplanted into a protected spot before moving to garden beds in the fall.
While I don’t have personal experience in growing primula from seed, I have grown other perennials using a similar process. I sow my seed into a single large container taking care to place the seeds evenly across the soil and with a little space between seeds. I cover with a thin layer of the same medium. (Primulas needs light to germinate so the vermiculite noted above is the better choice.) I cover the container with chicken wire – in my case, mostly to protect from the local squirrels but also to protect from extreme weather conditions. Once the true leaves appear in the spring, I transplant individual seedlings into 4 inch pots. I grow them in the pots through the summer and plant into the garden in the fall.
The advantage of this method over direct sowing is that you can better control the growing conditions. Keeping the seedlings moist is essential and easier to do in pots in a protected spot than in garden beds. The young plants will establish better by waiting till the cooler fall to transplant them. As with most perennials, I would expect limited bloom, if any the next spring and plentiful bloom in subsequent years once the plants are established.
When moving your primulas to the garden remember that they are woodland plants so situate them where they will receive partial shade and soil rich in organic matter. Note that Primula florindae is native to Tibet where it grows in the margins of rivers. When transplanting this species, you’ll need a site that never dries out such as a bog garden or the edge of a pond.
I hope you have great success with your primulas.
February 12, 2021