Hi all,

My first experience with japanese maple. I just bought Crimson Queen specimen in 1.73 Gal pot.
I need to choose from two pots to replant it: ~3 gal and 5.7 gal. The last one I planned as a permanent container for the tree and would like to use it, but I'm worried if it's too big for the plant current size.
Please advice which one should I use.

If you're only going to pot up, you can do so any time with no rebellion from the plant; but still, spring is the best time to pot up. You should not do a full repot on Acers while they are in leaf unless you defoliate the plant. A full repot includes bare-rooting (or nearly so), root pruning, and a change of soil, and should be done in fall after leaves abscise or in spring at budswell. Potting up ensures the limitations imposed by root congestion remain as a limiting factor, while repotting ensures the limitations are removed in their entirety, at least until the point in time where congestion has rebuilt to the point where the root/soil mass can be lifted from the pot intact, which is about when root congestion begins having an observable effect on growth rate and vitality. I forgot - if you decide to repot in fall, it's important to keep the roots from freezing temps over the winter.
Pot size is determined primarily by soil choice, but of course, the size of the root mass is a consideration. In an appropriate medium that doesn't hold perched water, you could plant the tiniest of seeds in a 55 gallon drum with no repercussions related to pot size. As your choice of media becomes more water-retentive, pot size becomes increasingly more important. I'm not sure what your intent (for the tree) is, but I wanted to help you avoid some potential problem areas if I could. If you have other questions, ......
Al

agofman said:Hi all,

My first experience with japanese maple. I just bought Crimson Queen specimen in 1.73 Gal pot.
I need to choose from two pots to replant it: ~3 gal and 5.7 gal. The last one I planned as a permanent container for the tree and would like to use it, but I'm worried if it's too big for the plant current size.
Please advice which one should I use.

Wait until the middle of winter, when your JM is at its most dormant, to repot. JMs can't handle their roots being handled when they're in active growth.

Pot size doesn't matter. I would put it in the pot it looks best in. You are going to have to do a partial repot/soil change every couple years anyway.

By the middle of winter, your maple trees will have had their chill requirement satisfied and passed out of deep dormancy into a period of quiescence, during which they are fully capable of active growth but held in check by temperature - as long as the temperature remains below about 45*. I have repotted hundreds of maples covering 10-15 species, and found that the best time to repot is from initiation of budswell to no later than the first signs of leaf emergence. Also, if maples are repotted in the middle of winter, they MUST be kept at temperatures above freezing. If they are not, the death of new roots and regeneration of their replacements can completely deplete the tree's energy reserves, which very often results in a weak spring flush (as the tree metabolizes starch at the base of buds for the push of leaves) followed by immediate collapse of the entire organism.


Al

If the pot is frozen solid, its a little hard to repot. I usually do it in the spring when the buds start to swell.

We don't know where agofman is located. When I lived in zone 8, I repotted any time in winter.

Why would it matter where he lives? Budswell happens when buds swell, no matter the calendar ...... and the pot [substrate] will not be frozen solid at budswell unless a genuine calamity has occurred.

I was campaigning against a mid-winter repot by highlighting some of the drawbacks. There are other good reasons not to repot any temperate deciduous tree in midwinter when mean temperatures are high enough to allow root growth but low enough to keep the top quiescent. This temperature paradox will almost always be the case for any over-wintered palmatums exposed to an appropriate amount of chilling, as, if you did a mid-winter repot and mean temps were warm enough to allow top growth, the tree would indeed be showing budswell. This is especially important for old trees that start to turn cranky at 50 years or so, though I know that's not the concern here.

Sorry to get off the track here, Agofman. Keep in mind that your choice of soil largely determines whether a pot is potentially too big for your tree. There are some tricks you can use if you want to move a tree to a pot/soil combination that has you concerned about over-potting. Let us know if you head in that direction or have other questions.
Al

Eventually, I decided to pot up and to put it into the bigger container. I live in Los Angeles, it's too long to wait for the cool weather and I'm not sure if dormancy can truly happen here. So I thought keeping it too long in a small nursery container is a bigger risk. Thankfully, I have a solid shaded area here where I can keep the tree.

Yes, if its a life or death situation, just do it.