Primula forrestii

[Cockcroft]

I live in the wet Pacific Northwest and am able to grow Primula forrestii from seed with little effort.  The bad news is that I can't seem to find the right conditions for getting my seedlings through the winter.  My experience is that this primula is not reliably hardy so it needs some cover over winter.  It gets botrytis from too much wet but doesn't like drying out either.  I've heard that folks in California can grow P. forrestii like a weed.  Anyone have suggestions on how to manage it in my environment?

Thank you.

Claire Cockcroft
Bellevue, WA  zone 7, sunny with high clouds and 50 degrees at the moment

[McDonough]

Claire, is the botrytis the primary cause for the seedling's demise over winter?  I might imagine that the prevalence of large slugs in the area to also play a factor in seedling loss, as the slugs like primula... as I mentioned once before, I lived in Bellevue WA for 4 years back in the 1980s.  When I gardened there, I had good luck growing plants that needed some moisture, but were sensitive to too much moisture and atmospheric dampness during winter months, by covering planting beds with a layer of sand... mature plants will eventually tap down past the sand an into a moist humus rich soil that a Primula might like, but the sand layer provided the necessary drainage around crowns of plants and certainly beneficial for small young seedlings.

[Cockcroft]

Thanks for the hint about sand.  No, slugs don't get the plants and the botrytis isn't the main cause of loss. The plants were in a deep planter.  Rotting seems to be the worst culprit with drought right there behind it.  A top dressing of sand might mitigate both factors and help me find the right balance.  Or the humidity in the air may just be too much for this species in my climate.

...Claire Cockcroft
Bellevue, WA (zone 7, sunny and breezy)

[Cockcroft]

I asked a number of people about Primula forrestii while I was in Nottingham for the International Alpine Conference.  The consensus was that P. forrestii is not hardy outdoors in my area.  One hint that might prove useful is to withhold water in the spring until there are signs of active growth.  Even though I moved my plants indoors to keep them from the cold, I no doubt did them in by watering too soon!

Claire Cockcroft
Zone 7-8, Bellevue, WA, emerging from the coldest April on record for our area

[McDonough]

I asked a number of people about Primula forrestii while I was in Nottingham for the International Alpine Conference.  The consensus was that P. forrestii is not hardy outdoors in my area.  One hint that might prove useful is to withhold water in the spring until there are signs of active growth.  Even though I moved my plants indoors to keep them from the cold, I no doubt did them in by watering too soon!

Claire Cockcroft
Zone 7-8, Bellevue, WA, emerging from the coldest April on record for our area

Hello Claire,  based on Flora of China, P. forrestii is from "open mountain forests, in limestone rock crevices; 3000--3200 m. N and W Yunnan", I would think that this species should be hardy, just a matter of finding out what it needs.  And no criticism intended towards our friends and expert plant growers on the other side of the pond, they have vast experience growing plants in pots and bringing unimaginably fantastic specimens to show, but maybe have less experience growing them outdoors, due both to their climate and the premium for land (most house lots in the UK are very small compared to American standards).  So, I'm not sure hardiness suggestions in this context are applicable; I would be tempted to try the plant in a variety of situations to possibly find a spot that works.

[Lori S.]

The following comments are taken from John Richards' Primula re: Primula forrestii (pp. 147-148):
- "Locally abundant in a variety of dry limestone habitats ranging from grassy plateaux to rock ledges";  NB.  Italics added for emphasis - this may corroborate the implied suggestion that excess water at the wrong time of the year (see below) may very well be the lethal factor, not cold.  (On the point of cold hardiness, it is said that it may occur up to 4500m!)
- "at flowering time in May, the habitat and the plant are dust-dry, and have received little precipitation for 8 months, although within weeks they will be deluged in a torrential and cease-less monsoon"; hmmm, tough plant!  Sounds like one I need to try!
- also very interesting:  "... may be very long-lived"; there is a reference to the same plant being seen by Halda in 1992 as was photographed by Forrest 80 years before, and then likely seen again by the author in 1995!

[Todd Boland]

I grew a few from seed last year...they were overwintered in our coldhouse...dropped to -16 C but the plants were kepp (unintentionally) dry.  All except one dried up too much and died.  One was pretty shivelled but about 2 weeks ago I resumed watering.  It has now plumped up and it putting on some growth.  Seems the dry period in winter is needed but once the temps rise above freezing, they need immediate water...looks like it will be challenging.