Long Internodes

[benbonsai]

Hi guys.

Was just wondering what causes longer internodes.
Is it from lack of regular pruning or not enough sun?

I have noticed the leaves of my Chinese Elm get a little larger and the internodes are starting to get longer also.

Thanks
Ben

[Daluke]

Lack of sun, lots of fertiliser and overcrowding = long internodes.

[shibui]

I don't think it is as simple as one cause. Certainly lack of sun does lead to longer internodes but I have my trees in full sun in spring and still get long internodes on early spring growth. I also see long internodes on young, vigorous trees so I think internode length is also related to the vigour of the tree. Most of the ones that start spring with longer internodes will gradually produce smaller ones as the season proceeds.
With a number of species here I now allow spring growth to elongate for a few weeks then cut right back to the base of any with long internodes. They respond by producing lots of new shoots from the node where old meets the stub of new shoot. Those new shoots generally have shorter internodes and are far better to use for extension to branches, trunks, etc. Be aware that where a cluster of shoots grow you will usually get thickening so take the time to reduce the number of shoots as soon as possible to maintain good taper.
Heavy feeding probably also contributes to vigorous growth with long internodes. Defoliating, reducing feed and water and removing long shoots will also remove energy and nutrients from the tree so subsequent growth is usually more compact.
Allowing sacrifice branches and or sacrifice shoots to take a large share of the tree's resources will cause other shoots to be weaker and more compact. At some stage the stronger shoots can be removed leaving the weaker ones that have short internodes to make the framework of the tree. This is often used in pine development (decandle in Dec. Subsequent shoots are small and restricted. Select shoots at the end of summer - take strong ones from strong areas leaving smaller, weaker ones but leave stronger ones on any weak parts to strengthen that area) That sort of regime can also be used with deciduous trees and probably other species as well.

Some trees - figs and elms are a couple that spring to mind have smaller leaves and shorter internodes near the base of all new shoots. Leaves get progressively bigger and internodes longer as the shoot grows. Deal with these by allowing shoots to grow 3-6 leaves then cut back to 1 or 2 leaves (or right to the base if 1st internode is too long as above) which will maintain a canopy of smaller leaves and shorter internodes.

[benbonsai]

Thanks guys
That helps a lot