I have a tree peony that started as a seedling from a plant of a friend gave me 8-10 years ago. I would like to try to propagate mine from seed. From the little I’ve read, it seems this is a difficult process. Can you help me?
I believe you are correct that propagating tree peonies from seed may be a little challenging. It can be done, but home gardeners may find it easier to propagate by grafting, which is described by a link at the end of this answer.
The American Horticultural Society’s Plant Propagation, edited by Alan Toogood (DK Publishing, 1999) rates seed propagation of deciduous tree peonies as moderate in level of difficulty. Another thing to bear in mind is that it will take several years before you see flowers on your new plants. In [late] summer, you would sow fresh seeds in pots and “provide two periods of chilling, such as two cold winters, with warmth between. Seeds are doubly dormant (roots emerge in the first year and seed leaves in the second). Guard against mice: they love the seeds.”
Another description of propagating from seed may be found in Jekka McVicar’s book Seeds (Lyons Press, 2003):
This seed has a double dormancy, producing roots in its first year and
leaves in its second. It needs two cold periods, with warmth in between.Collect ripe, fresh seeds in early autumn. Sow individually in pots,
using standard soil-less seed mix, either peat or peat substitute mixed
with coarse horticultural sand. Mix to a ratio of 1 part soil-less mix +
1 part sand. Cover with coarse grit, then place outside exposed to all
weathers. Visible germination occurs during the second spring. Grow on in
a cold frame for 2 years before planting out.
Excerpt on propagation methods from Plants for a Future database:
Seed – best sown as soon as it is ripe in a cold frame.When sown fresh,
the seed produces a root about 6 weeks after sowing with shoots formed in
the spring. Stored seed is much slower, it should be sown as soon as
possible in a cold frame but may take 18 months or more to germinate. The
roots are very sensitive to disturbance, so many growers allow the
seedlings to remain in their pots for 2 growing seasons before potting
them up. This allows a better root system to develop that is more
resilient to disturbance.If following this practice, make sure you sow
the seed thinly, and give regular liquid feeds in the growing season to
ensure the plants are well fed. We usually prick out the seedlings into
individual pots as soon as they are large enough to handle, and then grow
them on in a cold frame for at least two growing seasons before planting
them out when they are in growth in the spring.
The Heartland Peony Society has an illustrated tutorial on grafting tree peonies, should you wish to try this method.