I'm in southern Louisiana and planted 2 oldhamii, 2 golden goddess, and 2 Alphonse Karr bamboos roughly 4 months ago. I cut one culm off each oldhamii and planted 12 single node cuttings...only one rooted, but is doing great.
I'd like to get as many culm cuttings as possible to root over the next few years, as I have a 2 acre lot with plenty of space. I want to keep the rhizomes intact and use only culm propagation. No plans to try again until next spring, but I was wondering if anyone had advice based on personal experience with clumping culm propagation. What is the best time of year to attempt this with these three varieties? Also, I've seen people plant single node cuttings both vertically and horizontally. Which way do you recommend?
Generally, I will grow a plant in a pot and divide it into single culm divisions in late February, just
before new leaves start to grow. If new leaves are growing, then new roots are already growing, and they will be harmed by the division process. I also believe the plants have a larger carbohydrate reserve before growth begins. It seems to me that the plants do not recover from any disturbance as well if it occurs after they have started their spring growth. I find container division is the most efficient way to produce fairly large plants quickly. It also will result in 100% success, if done properly. I have started in the spring with a couple 3 gallon potted plants, divided in February, and had a couple dozen three gallon plants ready to be placed in the ground by October.
Since you do not want to use division, and I have some experience with cuttings in a similar climate, I will tell you what little I know:
I have seen many
Bambusa oldhamii plants that were started from single node culm cuttings, so I am sure they can be started efficiently this way. I have generally seen the cuttings done like this:
http://www.gatorventures.com/bamboo/b-oldhamii.shtml
Tips:
-As for timing, I recommend late February or early March, just before new leaves start to grow, for the same reason as discussed above.
-Remove most or all leaves, and the smaller branches.
-Cut the large branches back to a couple buds.
-Cover the culm node a few inches deep, but leave the upper buds on the branches above the soil.
-Some growers place the cuttings in pots at an angle (45 degrees) with the buds facing upward.
-Keep the cuttings in the shade until new growth has emerged.
-Water the cuttings every day, unless it is raining.
-Many people like to keep the hollow culm full of water.
-Use fairly large culms that are 2 to 3 years old, as they should still be vigorous and contain adequate stored reserves.
I have started some
Bambusa multiplex plants this way, but with low success. The plants were very small, and needed an extra year to catch up to even small single culm divisions. I have not heard of anyone having much success with
Bambusa multiplex cuttings. The nursery plants that I have seen always seem to have been started by division. In my opinion, a small culm diameter variety, like Golden Goddess, will be more difficult to root, as the culms have less volume to store reserves to keep them alive during the rooting process.
Air layering will work in some cases, as some
Bambusa species will grow roots into the air during wet weather. As Brad mentioned,
Bambusa ventricosa is such a plant; of course, it will also root fairly easily from cuttings. I do not know if air layering will work well with
Bambusa multiplex, as I have never seen them produce aerial roots. Even if it would work, it would be much more logistically difficult to air layer a large number of
Bambusa multiplex plants than it would be to divide a containerized plant into single culm divisions.
I have heard of people cutting partially through a culm near the base, so they can lean the culm and bury it in a trench while it is still attached to the parent. The branches are left above the ground. In theory, each buried culm node will produce a new plant. I have a feeling this will work with
Bambusa multiplex, but I have not tried it, as dividing potted plants is just so simple and effective.