For those of you who propagate your own plants here is an interesting new slant on Black pine seedling cuttings.This year I was lucky enough to get some Japanese Black pine seed from Scott in Canberra. Black pine seed is hard to find in Australia since quarantine have restricted the import of seed. I have been experimenting with growing black pine cuttings for a number of years with mixed success after reading about commercial grown P. radiata cuttings. The key to success is to use juvenile growth for the cuttings. P. radiata growers prune stock trees to force a flush of juvenile growth that is then set as cuttings giving good success.
For some time we have been aware of a technique for striking cuttings of very young black pine seedlings by cutting the stem at where it changes to purple and striking the top as a cutting. This is supposed to give better root structure to the resulting plant. I have trialled this but in my opinion the technique is slower, makes more work and the results are no better than using well root pruned seedlings.
I do, however, routinely prune my black pine seedlings to force low shoots that will give options for branching and can help to thicken the base of the resulting tree. Without early pruning you get a long, thin trunk with no low shoots.
This year after pruning the seedlings I recognised that the left over tops were the ultimate in juvenile pine growth and decided to test the rooting ability. The results were very good as shown in the step by step pics below.
- Black pine seedlings
The tall, thin seedlings in this pic have not been pruned. The ones with multiple shoots on the right have already been pruned once to show the multiple shoots from a pruned seedling.
strip lower leaves
dip cuttings in rooting compound
set cuttings in propagating mix
4 weeks later.....
14 have roots, only 1 not yet showing roots
trim roots to promote even better nebari
The first set of cuttings consisted of tips about 5 cm long. A subsequent try used pieces up to 9 cm long and cuttings from the stem without tips as well as tip cuttings ( see pic below) but results are not available at the time of this post. The cutting mix is 50/50 coco peat/ perlite and the cuttings are placed under intermittent mist to maintain humidity. I don’t have bottom heat. The original cuttings were taken in January (mid summer in Australia) and potted up in mid February. The majority produced multiple roots from the base of the cutting which should give good nebari in the resulting trees.As you can see, the advantage of this technique is that you can get 2 or more trees from each seedling as well as getting more trees with good rootage. In future trials I will try this at other times of the year. It will also be interesting to see how long the seedlings (and the resulting cutting grown plants) retain their juvenile rooting ability.