Last year I had the rare opportunity to buy a batch of P. brownii seeds, although with the warning that it would be the most difficult species to germinate. Well, in the first version of this article I was still hopeful about them as two of them germinated, but they have since died, so we had to update the article otherwise... Martin Page, author of several books on peonies, warned about this:
"Paeonia brownii is one of the most difficult species peonies to grow because it needs extremely well-drained soil and full sunshine throughout the day. If you want to try your hand at growing it you should build a raised bed and fill it with a mixture of soil, compost, sand and grit." ((footnote:Page, M. "The Gardener's Peony." Timber Press, Cambridge/Portland OR, 2005, pp. 40.))
The goal of growing this species is using it in my hybridizing program, although chances are small that much will come from it. Galen Burrell, who did much species crossing, only had one seedling from it in his lifetime (with P. peregrina pollen), and it did not survive. ((footnote:Burrell, G. "New first generation peony crosses." In: American Peony Society Bulletin, no 321, March 2002."
Full text available online at: http://www.paeon.de/aps/bull/321/321_burrell.html)) There's no other report of any success with it. It is quite probably far more difficult to obtain an intersectional hybrid (section Onaepia x (Paeonia or Moutan)) from it than it is to make a so-called ITOH intersectional hybrid (section Paeonia x section Moutan) because the differences are far greater still. As Tao Sang, peony researcher, would have it:
"The earliest evolutionary split within the genus Paeonia might have occurred between section Onaepia and the other two sections if the molecular clock is assumed. Morphologically, section Onaepia is also distinct from the other two sections by its small flowers (2-3 cm in diameter vs. > 5 cm in sections Moutan and Paeonia) with fleshy and strongly concave petals." (...) The divergence time between section Onaepia and the rest of the genus (...) is estimated to be 16.6 million years ago. ((footnote:Sang, T.; Crawford, D.J. & T.F. Stuessy. "Chloroplast DNA Phylogeny, reticulate evolution, and biogeography of Paeonia (Paeoniaceae)." In: American Journal of Botany, vol 84, 1997, pp. 1120-1136))
If you want to read an excellent longer article about this peony, the following is at your disposal:
Vance, N. "Finding Brown's peony a sweet attraction" In: Kalmiopsis, vol 19, 2012, pp 1-6
For those that want to try growing this native North American species, it might be interesting to read this account Galen Burrell wrote for the readers of the American Peony Society Bulletin (published quarterly, become a member of the APS if you want to receive this publication)
"NOTES ON OUR NATIVE PEONIES
Galen Burrell, P.0. Box 754, Ridgeﬂeld, Washington 98642
(For P. brownii seed, see end of article)
In August, I made what has become my annual trip to south central Oregon to collect Paeonia brownii seeds. I was a little apprehensive of my chances of ﬁnding many seeds, since last year a drought had caused most plants to go dormant by early August, and most plants had not produced seed. This year would hopefully be different since there had been record snowfall and adequate Spring rains. Peony growers, however, say that the year previous is what makes the flowers and hence the seeds for the following year. Anyway, my hopes weren't too high.
As it turned out, there was no need for concern. All of the peonies were still green — not a sign of dormancy. Most plants had produced abundant seed crops. On one of the largest plants, I counted more than 500 seeds. One flower, on the same plant, had 9 follicles (pods) that contained more than 40 seeds.
Since the plants were not dormant and showed no signs of dormancy it can probably be assumed that Paeonia brownii does not need a dormant period in late Summer. Like Mediterranean peony species it appears that dormancy is an adaptation to dry Summers and not necessarily a requirement. This is good news for those who try to cultivate Paeonia brownii in wetter climates.
I tried to collect a few seeds from as many plants as possible, so that I did not take too many from any one plant. I also planted seeds throughout the colony. For some reason this colony has an abundance of very large plants, but few small plants. By planting seeds I hoped to increase the number of small plants. Besides, sticking my finger in the porous, volcanic soil to make a planting hole was great fun — kind of like planting sweet corn when I was a kid.
I sent most of the seeds I collected to nurserymen, botanical gardens, and individuals in the U.S. and many foreign countries. It seems that Paeonia brownii is a very rare plant outside of its range. I also kept seeds for my own attempts at growing Paeonia brownii.
Last year was my first attempt at growing this ﬁckle plant. Nearly all of the seeds I planted in the Fall came up in late February, but most soon died after producing their ﬁrst true leaf. The only survivors were those planted in raised beds that had been filled 2 feet deep with 1/3 sand, 1/3 peat, and 1/3 humus-rich top soil. All of the seedlings that died were in clay soils.
I also planted seeds of Paeonia californica in the same raised beds. These seeds came up about 2 months later than the Paeonia brownii seeds, but grew faster.
It turns out that Paeonia brownii needs cold temperatures to germinate (this can be done in the refrigerator) while Paeonia californica does not. Some of the Paeonia californica seeds that I planted in pots this Spring came up in September.
Drainage seems to be the key to successfully growing Paeonia brownii and Paeonia californica. This year I am going to experiment with planting mixes containing different parts gravel, grit, sand an top soil. With a lot of patience and a little luck I hope I can learn how to successfully cultivate our native peonies so these strangely beautiful plants can be grown in gardens. ((footnote:Burrell, G. “Notes on our native peonies.” In: The American Peony Society Bulletin, 1993, no. 288, December, pp. 6-7.))