Primula Species, Hardy Primrose, Japanese Primrose

I have found primula kisoana easy to grow in my garden. I have had it for many years. It has spread to form a good size patch in medium...Read More shade but it is not aggressive. Some years a few bare spots may appear but they always seem to fill back in in the following year. My soil tends to clay but I have supplemented it over the years with peat moss and maple leaves. In addition to the pretty flowers, the foliage is very appealing and it has furry pink and green stems that are very attractive. It does seem to appreciate even moisture but tolerates a dry spell now and then. I have tried it in drier areas of my garden but it did not flourish there.

This is the only primrose species to have survived more than two years for me - in fact, about 5 years for me. I think it grows in drier ...Read Moreconditions that some people above think - more of average soils but maybe in average soil it is smaller. I got it from a plant sale by the local garden club - previous I had it in more sunny location and drier location but competitions from other plants were intense so I had the three to four plants (tiny) moved to the new home - only one had come up so far. Blooms in May. At least now I know it's name!

The following notes on germinating P. kisoana are quoted and paraphrased heavily from the 2nd edition of Norman C. Deno's book, Seed...Read More Germination Theory and Practice. He found that this species germinated in only two procedures:

1) It germinated at 70*F in the dark with GA-3 (gibberellic acid) using fresh seed (germination was 70% successful in the second week), OR

2) at 70*F in the light with dry-stored seed.
Germination was highest with seed previously stored in dry-storage for 2 years at 70*F and then germinated at 70*F in the light with 80% successful germination in the 1st through 3rd weeks. However, when he tried to germinate seeds identically to the foregoing except for dry-storage being 6 months, instead of 2 years, germination was lowest.

[ If you obtained your seed through trade or a commercial source and don't know how or for how long the seed was previously stored, then give them 1 - 6 weeks at 70*F in light during which best germination should occur. If nothing happens, then cycle the seed through 40*F for 3 months, then 70*F in the light again for 3 months, back to 40*F for 3 months, then 70*F for 3 months.

I just received seed of this plant this month and am tempted to wintersow it immediately, but Dr. Deno's patterns of germination apparently begin in warm temperatures, so I will use his baggy method (see Haberlea rhodopensis in PlantFiles) adapted per the foregoing. If you have enough seed, I think it would be worthwhile to try the wintersowing method just to see what happens.]

Dr. Deno also wrote "Unraveling the Secrets of Primula Kisoana" in the Bulletin of the American Rock Garden Society, 50, 211, 1992.

He notes that the Cortusoides group, to which P. kisoana belongs, "...is well suited to conditions in eastern U.S. and should be grown more as they are beautiful floriferous plants." So, if you live in the eastern US and have a shady, moist spot, I hope you'll try this plant, because Dr. Deno also notes that Primula kisoana "is reported to be EXTINCT in the wild."

I 've been successful with this verry pretty primrose for several years here in NE Pa. I've got in near my spring-fed pond - cool & mois...Read Moret soil. It spreads by slowly by stolons.