Almost all the common techniques for propagating your katsura tree will work.
Katsura propagation key facts
Success rate – high for seeds, low for cuttings
Difficulty – easy
Time – 4 weeks to a year
Yield – depends on technique
Katsura seeds are among those plants that have fully mature seeds when the pods are ripe. This means the germination rate is highest when the seed pod has just barely turned dry.
- You can sow them immediately for highest results.
- However, for areas with cold winters, it’s also possible to wait.
Time your sowing so that seedlings may be transplanted to the ground either in spring (with regular watering) or in fall (less need for watering). Germination takes less than two weeks. Allow for one month growth before transplanting.
- Grow katsura from seed (full article)
Seeds that are stored in a dry area for over three weeks usually go dormant. They don’t germinate as easily. Dormant seeds will only have a germination rate (for katsura) of about 20 to 40 % (1 or 2 in 5 seeds). If you want to increase this rate to around 80 or 90%, you can stratify them.
Thanks to the wonders of cross-pollination, each seed will give rise to a genetically unique individual tree.
- You might give rise to a new, surprising cultivar that blends characteristics from the mother plant and the (usually unknown) father plant!
Another advantage also is shared by all dioecious trees:
- If you’re allergic or sensitive to pollen, you should plant only female katsura trees. They won’t release any pollen at all!
Cuttings from katsura trees
Preparing cuttings from a katsura tree is possible, but not as successful.
When to take katsura cuttings
Late spring and early summer are the best times to prepare cuttings from a katsura tree.
- This matches the time recommended for pruning.
- New growth is still soft and flexible at this stage, so these are softwood cuttings.
There are two ways to make cuttings from a kastura Cercidiphyllum tree. These are stem cuttings and basal cuttings.
- Stem cuttings – aren’t very successful, sometimes success rates even drop down to single digits, as in one in ten. But it isn’t hopeless at all, since it can also reach much higher levels if the conditions are right.
- Basal cuttings – much higher success rate, but often more difficult to properly start. Indeed, these are taken from portions of a branch where stems connect. You can also use suckers that start shooting out from near the base of the trunk. It takes a little practice to get this done well, and there aren’t always many suckers to work with.
- Read our dedicated page on katsura cuttings
Katsura is also very successfully layered.
- This is especially helpful for those katsura types that are weeping, like the ‘Pendula’ and the ‘Tidal Wave’.
How to layer katsura
- Simply place large pots wherever branches reach to the ground.
- Cross a branch across the top of the pot and anchor it down with a metal hoop. Make sure several leaf nodes are covered. If need be, arch the branch down into the pot.
- Fill the pot with a mix of garden soil and soil mix, heaping it all the way to cover the branch with about 4 inches of soil (10 cm).
- Load the soil down with a couple larger rocks. Make sure any rain flows into the pot and not out of it, though.
- In windy areas, stake the branch to make sure it doesn’t rip out of the pot or tip it over.
Roots will grow from the nodes. After a year (two when the growing season is short), you can cut the mother branch away and transfer the pot.
- To straighten the sapling, if horizontal, simply transfer the entire clump to a larger pot – sideways!
Other katsura propagation techniques
Since the Katsura tree is endangered in the Chinese portion of its natural habitat, efficiently propagating the tree has become an important field of research. Micro-propagation is one such new technique.
The goal is twofold:
- increase availability of seedlings and saplings to repopulate other areas, or for commercial resale
- make genetic sampling more effective.
Genetic sampling consists in collecting as many different individual trees as can be. This helps create a stock of genetically diverse plants where each is unique.
- Since natural habitat in China is drastically falling, it becomes important to try and “save” the genetic heritage of as many different katsura specimens as possible.
- For dioecious plants, this makes conservation efforts easier as it helps reduce in-breeding.
That’s why current research is focusing on making micro-propagation easy and quick.
- A team of researchers could sample many different trees on a transect or in a park and successfully propagate each one upon returning.
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Katsura flowers by Kristine Paulus under © CC BY 2.0
Seed pods on Cercidiphyllum by Danny Schissler for the Plant Image Library under © CC BY-SA 2.0
Katsura softwood growth by Danny Schissler for the Plant Image Library under © CC BY-SA 2.0