This post is long overdue. The single biggest mistake tree planters make when using tree tubes is that they remove them too soon. As we have discussed, tree tubes are meant to fill three roles throughout the course of their life: Establishment, support and bark protection.
In the establishment phase (1 to 3 years) the tree tubes protect seedlings from animals, reduce moisture stress (to enhance survival and growth) and shield seedlings from herbicide & mowers, to get seedlings off to a successful start.
At the point in time that the trees emerge from the tree tubes they will have a thinner stem relative to their height than trees planted without tree tubes (the difference being, of course, that trees planted without tree tubes often NEVER reach that height). Tree tubes are DESIGNED to stay in place to support the trunk of the tree after it emerges from the tube, until the trunk thickens up.
Even when the trees are self-supporting they are still at risk for bark damage from deer (buck rub) and rodents. Tree tubes are meant to be left in place for continued bark protection until the trees reach 3 inches in diameter at the base, at which time the tubes should be removed and disposed of.
HOWEVER. Tree tubes are a significant investment for the hobbyist tree planter, and the idea of re-using tree tubes is very tempting... or even in some cases necessary. Keep in mind that every time you remove a tree tube before it has completed its full job of getting the tree to 3 inch basal diameter you are taking the risk that something will happen - wind storm that breaks the stem, buck rub, gnawing rodents, mower damage - that will either set the tree back or even kill it.
The sooner after emergence you remove the tree tube the greatest the risk to the tree. Tree planters have been successful using two different methods of re-using tree tubes.
Good (highest risk but also highest number of uses for each tree tube): Remove the tree tube shortly after the tree
emerges, but tie the tree to the stake you were using to support the
tree tube. Preferably this would be a flexible stake like pvc. I´m not
a huge fan of this practice – I don´t like staking trees and of course
it exposes the tree to rodent and deer damage. But I have many
customers doing this successfully and it does mean you can use the tubes
two or three times.
Better (less risk and affords opportunity to re-use the tree tube once): After the tree emerges wait at least one full
growing season and then remove the tube. Especially when using pvc
stakes the tree will gain a lot of caliper in that first growing season
after emerging from the tube, and should be self supporting at that
point. The advantage is the ability to reuse the tube (and
probably the stake if the tree can stand alone); the disadvantage again
is exposing the bark to rodents and deer damage.
Best of all, of course is to keep the tree tubes on until the trees reach 3 inches in basal diameter. At that stage you can remove the tree tube knowing it has completed the three functions for which it was designed, and safe in the knowledge that the tree is successfully established.
But if budgetary restrictions mean you have to re-use tree tubes in order to meet your planting goals, these guidelines will help you weight the risks of the various methods and will give you the best chance for success.