First, you must know that the pines are extremely difficult to propagate by cuttings. Some varieties of Japanese white pine are easier than others. The cultivar ‘zuisho’ ‘is probably the one best for cuttings and many other aspects. Otherwise, among the parameters we can control:

1) there are certain times of the year it is best to propagate by cuttings

2) certain types of branches to choose

3) ideal substrates for cuttings

4) culture conditions preferred for the process to work

1) there are certain times of the year it is best to propagate by cuttings

A: According to a Bonsai Today article relying on what is done in Japan, the ideal time for cuttings is in March or April, ie just before the buds begin to swell. B: David Easterbrook rather recommended me to take cuttings in mid June, just after the new shoots of the year began to lignify. I did both tests with 10 zuisho cuttings in March and 10 cuttings in mid-June. Finally, David’s method has worked best for me. 8 of 10 cuttings taken in March died before the end of the summer. The other two have spent the summer but did not root. In contrast, 9 out of 10 cuttings taken in June lasted until the end of the summer with no problem, as far as I often sprayed them (2 times a day).

2) certain types of branches to choose

When doing a white pine cuttings from Japan, one must make sure to take the most vigorous branches on your tree. If the branch is small and has little foliage, your chances of success are practically nil. So be sure to take branches that are very much alive and with several buds at the ends: it is a sign of strength. Do not take too long nor too thin or branches too thick. One should choose the branches between 4 and 9 cm in length with a diameter of about 4-5 mm. The cuttings should also have the right amount of foliage. Leave too much, and the cutting will lack water and dry. If you do not let enough, the cutting will lack photosynthetic area to produce energy. Remove all needles along the branch and leave a crown of needles to the end of the branch. Only this part is above ground. (See photo).

3) ideal substrates for cuttings

An ideal substrate for cuttings. The easiest way is to prepare it yourself with the remnants of your soil sifting. The mix is ​​simple. The finer the grains are recovered when screened perlite and turface 50/50. It sounds like a substrate that drains well but it is also able to retain some moisture. Again, look at the image above to get a general idea. Also make sure to have them in a pot that drains well. If there is just one single hole in the bottom of your pot, it will stay too wet and your cuttings will rot. A heating pad can help prevent mould set in.

4) culture conditions preferred for the whole thing to work

 Ideal growing conditions. First and foremost, you must avoid freezing. If it freezes, the cuttings will die, even after 8 months. Then, you have to wait 2 years before even thinking about repotting them. This winter, I tried to repot the ones I made in March and June. I was left with 10 of 20 which were still healthy, and on the 10, only 2 had roots (in fact, each of the two cuttings had a thin root). In the first repotting I broke the only root because it was ultra sensitive !! I managed to repot the 2nd cutting without breaking the root, but just the fact of repotting it made it die. Next in line, you will need to keep the cuttings in the shade and sheltered from the wind. I keep mine in my greenhouse to avoid the wind. If there is too much wind, the cuttings will dry out. For watering, wait until the substrate has begun to dry before to water again. Pines like to be on the dry side for their roots, but make sure that cuttings do not lack water. Spray the foliage as often as possible in summer when it’s hot. The more frequently the better. It will take 5 years for the cuttings to get really strong.

Conclusion

In short, it’s really complicated to pine cuttings. I hardly miss any cutting with other species, but with the pine I have managed only 2 out of 20, and I botched them. Currently I still have 2 that survive in the original pot, but I have no idea whether they have developed roots or not. If the cultivar you are trying to reproduce by cuttings does not have some very special qualities like the zuisho, Kokonoe or Miyajima, I would say that you do not waste your time with pine cuttings. You can buy Japanese white pine seeds you will have much more success. Nevertheless, if it is a special cultivar, you have no choice but to go through cuttings or grafting because zuisho seeds for example will not hold the special characteristics of the mother plant. That’s why I do cuttings of zuisho. It also seems that with the zuisho, after the first 5 years or so, the tree gets almost to double in size every year!