Let’s face it; some places are just too small to accommodate a mature, large-in-stature, full size tree. It comes down to soil volume or just the size of the space the tree will take up a few years later, after planting.
Apartment dwellers, small condo’s, office building breezeways come to mind, but what to do? A tree can exist in a container for it’s whole life, given the right amount of care.
The list of trees I’ve seen humming along for years in pots is long indeed! Think bonsai specimens and you get the idea. The first consideration would be the tree itself, You don’t want to have to wrestle a huge monster every time root pruning comes around and at certain times (about every 2-6 years) you will be doing just that. Next comes the pot, and not just any old pot will do.
The container must be widest at the top, or removing the tree for root pruning will be a royal pain. A half wine barrel can make for a great “home” for your small tree but wood only lasts so long. The best thing about potted trees is you can move them around to suit your desires. Sometimes just spinning them around a few degrees changes the whole look. If the planter is on smooth ground, having the planter on casters or a little dolly makes for an easy adjustment! Your chosen container must have DRAINAGE or your poor tree will suffer until it croaks, so make sure the container drains water well with soil in it.
You will need to mulch your mini tree the same as you do with a ground planting, and if you fertilize, go easy and don’t over do it with a lot of anything high in nitrogen. Kelp and beneficial fungi are just fine, however. Lighter colored or wood pots will keep soil temps down, and helps roots to stay happy!
When the time comes for root pruning you will need a sharp set of shears/hand pruner, a garden hose, and a strong friend. Around January or February will be the ideal time for pruning roots, assuming the tree has been living outside.
Pull, wrestle, and weasel the tree out of its container and set it some place that can get muddy. Wash as much of the soil away as possible and tease the root wad down with your fingers as best you can. There will be more of a root mass than you think! Measure the depth of the pot (roughly) and cut off everything that wont fit. But try to leave the structural, bigger roots to stabilize the tree in the new soil. I have cut over 50% of the roots off of potted trees with seemingly no damage, but timing is more important than anything.
I like to spread the root mass over a big rock in the planter to keep the settling to a minimum, but it isn’t a must-do.
Replace the soil mix gently but firmly packing it around the roots and eliminate as muck air space as possible. Every spring or so, aerate with a chopstick or the like vertically AWAY from the stem and root collar. and again, check for DRAINAGE, this is most important.
If you decide to do trees that aren’t cold tolerant enough for the teens/single digits that we can encounter here, a string of Christmas lights will warm them enough, besides looking cool, just don’t use LEDs as they don’t put off enough heat.
The bigger the pot, the bigger the root volume, and it comes down to how big a tree we want to move around, root prune and the space available, but you can pretty much have any tree you want, any where you want. Plant high and often, and enjoy your autumn!