After my success with sea buckthorn and beach plum and hazel, I’ve been thinking of how to incorporate the technique into our annual plant propagation efforts. Much of the information on the Internet relates to herbaceous perennials not woody plants although there are some very useful gems such as Peter Del Tredici’s Shoots From Roots: A Horticultural Review. That the technique is not much used for woody plants is explained by Charles W. Heuser in Factors Controlling Regeneration from Root Cuttings:
The inconvenience of securing root cuttings is a strong deterrent. Either the whole plant must be dug to secure appropriate root pieces or else the soil must be excavated around the plants to expose the roots. Either method is tedious, labor intensive and usually must be carried out during the fall and winter months.
Drawing on my experience with beach plums, I think I have a solution to the problem outlined by Heuser.
For the sake of discussion, let’s say that I want to produce a steady stream of beach plum plants. Instead of planting out the beach plum that I currently have in a pot, I will keep in it the pot and sink it in the ground in the fall to overwinter it. In the spring, I will dig it up, take the plant out of the pot, carefully shake/wash off the dirt so as to not damage the root hairs, take root cuttings, and re-pot the plant.
I could repeat this process each year replacing the “mother” plant as it became too big for the pot with one of the plants produced from a root cutting. This would seem to be a very easy way to obtain a steady supply of root cuttings and, hence, plants.
It seems to me that this is akin to stooling or trench layering in that a “mother” plant is used to produced identical offspring.
I suspect that timing is very important. If a plant stores up energy going into the winter in order to generate new growth in the spring, it would seem to be important to catch the spring energy burst by taking cuttings in the spring while the plant is still dormant. Keeping the potted cuttings in a warm, protected out door location where they can respond to natural conditions would at their own pace would seem to make more sense than attempting to arbitrarily control the process.
We have a number of young trees in this year’s version of last year’s Lower Trent forest effort that I’d love to propagate – red maple, black cherry, serviceberry, white cedar. It will be an easy exercise to take root cuttings next spring before they break dormancy.
Footnote: The female sea buckthorn cutting and the hazel cutting both failed. They were doing quite well until I got ahead of myself and put them in direct sunlight. It was too much for them and they wilted and died. That suggests that while there may be green growth showing, the roots have not yet started to grow and the plant is still very tender. Lesson learned? Be patient.