Division of tree peonies is so uncertain and slow that we must resort to grafting—a specialist’s job if ever there was one—to propagate this plant.
Different Propagation Methods
Grafting Tree Peonies
Japanese gardeners used to graft peonies on roots of the wild species, suffruticosa, but so much trouble arose from the vigorously sprouting habits of these understocks that it became the general custom to graft the tree peony scion onto a root of the herbaceous peony.
Currently, grafts made on another wild tree peony species, lutea, are being worked with.
But it is in the form of graft on a herbaceous root, and you will buy most tree peonies now on the market.
Our top growers are advancing in propagating techniques that tree peonies may be plentiful enough for all of us to afford them before long.
There is another method of propagation—from seeds. This results in a great variety of new plants rather than more of the old.
There is great interest, I find, among gardeners for information on growing for themselves tree peony plants not prohibitive in price.
Because I hear frequent lamentations of failure to germinate the seed, I shall impart a horticultural secret known to few.
You will find it successful if you follow the instructions carefully. I regularly get 40% to 60% percent germination from fresh seeds in this way:
- Seed is sown in flats when ripe, usually in October in my latitude.
- I fill the flats, which may be 4” inches deep, with soil to within ½” inch of the top.
- After the seeds are planted, I cover them with ¼” inch of clear sand. This keeps down the growth of weeds and moss and secures a more uniform degree of moisture.
- I put about 200 seeds into a flat 12” x 20” inches.
- These flats go into a frost-proof cellar for the first winter and may stay there or be put in a shady corner of the garden the following summer, seeing that they do not dry out.
- When October comes, the flats must go back into the frost-proof cellar. Their germination will begin in November or December.
- As soon as a few young plants show, the flats should be taken to a local greenhouse (unless you are fortunate to have one of your own). Here they have light and warmth, and germination goes on rapidly to have a good stand of young plants by the middle of winter.
- The flats should remain in the greenhouse until about the middle of April or May.
- The foliage is delicate at first and should not be subjected to trying conditions until it has begun to toughen. Hence, when brought out, the flats are set in the shade in the garden until July, when the young plants may be set in their permanent quarters.
When transplanting the seedlings, you are almost sure to find several seeds just beginning root growth, getting ready, in fact, for leaf growth the following -winter or spring.
These seeds should be saved and replanted in the flat, and you will get the second germination during the following winter.
I usually get about 50% percent germination in the first lot and about 10% to 15% percent in the second.
The little plants will grow steadily, although they won’t flower until the sixth or seventh year from seed.
If you are in a hurry for blooms, perhaps you had better plant petunias instead!