Hi Amy... You have to look at the long range...How is it going to do in the long months of winter in a mix that harbors gnats? Usually gnats is a tell tale sign that your mix is too organic, and holds moisture far too long... If it were my tree, I would gently repot it into a far superior mix than what it is in now to prepare for your tree for the winter months and now shorter and cooler days. I would remix that mix with 50% perlite or more until you can fully understand how to make a good mix from scratch in spring, or buy one that consists mostly of pine bark, a little perlite, with a very small amount of peat... Make sure to have the basic tools you will need to carry her threw at the ready... A wooden dowel, or your finger if you are good with that, a nice sunny spot, learn how to water and when, a good pesticide, and keep reading........... No one can say for sure if your tree will suffer if you repot again, but I would tend to believe not:-) I wish you much success! MIke

I successfully tend to some 200 containerized trees that are in various stages of development for bonsai, many are Acers. I lecture regularly by invitation on container culture in general, and many other tree-related subjects. My next presentation is Wed, May 6, to the Gladwin County, MI Master Gardeners. The above-ground portion of trees are able to tolerate much colder temperatures than roots. 14* is considered the industry standard for killing low for mature rootage on A palmatum, so it's inaccurate to say that roots are fine above 15* soil temps and in jeopardy at temperatures below 15*. Succulent rootage and hair roots are often unable to tolerate temperatures only slightly below freezing. As temperatures fall, larger and more lignified roots succumb to the cold. As stated above - all roots on a plant are not created equal when it comes to cold tolerance. 12-24 inch (deep) soil temperatures rarely see temperatures drop much below 25*, but the top 6" of soil, where the bulk of our containerized tree's roots are - does get extremely cold - certainly well below killing lows for fine rootage (though perhaps not for larger roots). I could site Dr. Whitcomb for support, but I'll let you look at his text at your leisure, since it appears you have it. Note Chapter 13, pages 308 -338 to see that what I'm saying is not only logical, but it's supported abundantly in his work as well as a plethora of other literature. Something I wrote previously: "Commonly, each species of plant has a general range of cold-hardiness. Within species and cultivar, cold-hardiness is genetically determined. That is to say that a plant that is propagated from cuttings or tissue culture will have the same ability to resist cold as the parent plant. Plants cannot "develop" a greater degree of cold-hardiness by repeated or prolonged exposure to cold, even after 100 years (trees). If we pick any plant at random, it may or may not be able to withstand freezing temperatures. The determining factor is the plants ability to prevent freezing of bound water. Bound water is the water inside of cells. There are actually three kinds of water to consider when we discuss "freezing". The water held in soil - When this water freezes, and it can freeze the soil mass solid, it doesn't necessarily kill the plant or tissues. Then there is free or unbound water, also called inter-cellular water. This is water that is found in plant tissues, but is outside of living cells cells. This water can also freeze solid and not kill the plant. The final type of water is bound water or intra-cellular water. If temperatures drop low enough to freeze this water, the cell/tissue/plant dies. This is the freeze damage that kills plants. Fortunately, nature has an antifreeze. Even though temperatures drop well below freezing, all plants don't die. In hardy plants, physiological changes occur as temperatures drop. The plant moves solutes (sugars, salts, starches) into cells and moves water out of cells to inter-cellular spaces in tissues. These solutes act as antifreeze, allowing water in cells to remain liquid to sometimes extremely low temperatures. The above is a description of super-cooling in plants. Some plants even take advantage of another process to withstand very low temps called intra-cellular dehydration. The roots of your trees can stay frozen for extended periods or go through multiple freeze/thaw cycles w/o damage, so long as the temperature does not fall below that required to freeze intra-cellular water. If roots remain frozen, but temperatures remain above killing lows, dessication is the primary concern. If the tree is able to take up water, but temperatures are too low for the tree to grow and make food, stored energy becomes the critical issue. Dormant and quiescent trees are still using energy from their reserves (like a drain on a battery). If those reserves are depleted before the tree can produce photosynthesizing mass, the organism dies. There are a number of factors that have some affect on the cold-hardiness of individual plants, some of which are length of exposure to seasonal cold, water availability (drought stressed plants are more cold tolerant), how recently planted/repotted, etc No one can give a definitive answer that even comes close to accurately assessing the temperature at which bound water will freeze that covers an entire genus, or even species. Unbound water is of little concern & will usually freeze somewhere around 28*. Some material will be able to withstand little cold & roots could freeze/die at (actual) root temperatures as warm as 25-27*. Other plants may tolerate much colder actual root temperatures - as low as 10*. There's just no way of knowing unless you have a feeling for how cold-tolerant the genetic material the plant was derived from might be, and finding out is expensive (from the plant's perspective). ;o) It's wise to remember that root death isn't instantaneous at one particular temperature. Roots succumb to cold over a range of chill with cultural conditions affecting the process. The finest roots will die first, and the slightly thicker and more lignified roots will follow, with the last of the roots to succumb being the more perennial and thickest roots. Since any root death is a setback from an energy allocation perspective, and root regeneration takes valuable time, it's probably best to keep actual root temperatures in the 25-40* range as long as we can when the tree is resting, even though the organism as a whole might be able to tolerate lower temperatures. Even well established trees become very much like cuttings if all but the roots essential to keep the tree viable are lost to cold. Regeneration of roots is an expensive energy outlay and causes the trees to leaf out later than they normally would and shortens the natural growth period and reduces the potential increase in biomass for the next growth cycle and beyond." Summary of what I originally put forth: If you repot in fall, you should protect roots against freezing temperatures or you will lose a portion of the roots. It is an expensive outlay from an energy allotment perspective for the tree to have to regrow these lost roots. The energy that goes into regeneration of roots lost to cold could/would have been used by the tree for foliage production and branch extension. Winter-killed roots represent a loss in potential biomass increases and it makes no sense to adhere to a practice that doesn't take cold-damage into consideration - unless you wish to use it as a tool to slow trees down. Al

14* is generally considered the industry standard as the lowest temperature mature roots of A palmatum can tolerate. This means that the entire organism would be expected to succumb to temperatures that low. I agree wholeheartedly with Pam re her assertion that root damage can/does occur in A palmatum at temperatures as high as 24-26*, and I might even consider a couple of degrees warmer than that as a favorable lower limit, just as an added margin for safety. Even though our trees might survive root exposure to lows in the neighborhood of 14*, they sure won't like it. Roots don't all die at the same temperature, they die incrementally as the temperatures drop. While it varies by species, and genetically by individual plant within that species, all roots on the same plant don't have the same tolerance to cold. These numbers may not be accurate, but it gives you the feel for what I'm talking about. We say that maples are X hardy because they tolerate low air temperatures, but what about root temps? Most temperate trees, even in zone 4, never see actual 6" soil temperatures much below 27*, with 25* being unusual. This is true, even in bare field agricultural conditions. Half of Michigan's upper peninsula, under cover of forest canopy, never even sees frost in the ground. We know that the finest hair roots - the most succulent and the ones that do the lion's share of the work are the first to die. In many woody plants, these roots begin to die as soil temperatures drop below 28*. As temperatures drop further, larger and larger roots succumb to killing low temperatures. The point is - that many trees that SURVIVE are left with only the largest roots to support them in spring because much of the rootage has frozen. These trees are slow to flush in the spring because they need to utilize stored energy to regenerate lost rootage before they can move sufficient water and the nutrients dissolved in water to support either growth or the flush of foliage that makes the food that allows the tree to grow (this, in the case of deciduous material). So, while some trees might survive at extremely low temperatures unprotected, we KNOW it is better for the tree, especially from an energy management perspective, if we give them protection that ensures actual root temperatures don't drop low enough to kill even the finest roots. For most temperate trees, that means we should strive whenever possible to keep low root temperatures in the upper 20s at their lowest, and below 42* to inhibit the onset of growth until spring, when we can get them into good light w/o worrying about frost/freeze. So, what the tree might tolerate and what's best for it are two distinctly different perspectives. Al

It looks like many of those buds are still viable, so I doubt you have too much to worry about. The most important factor to consider when growing a JM in a container is the quality of the potting medium. The potting medium needs to be of a very high quality - durable yet freely draining. Rather than going into all the details now, I'd suggest you research the forum archives about growing JM's in containers or check out the Container Gardening forum for helpful posts on potting soils. Of especial interest would be a recurring thread on that forum about growing trees in containers. Since I can't see either the soil or the size of the container in the photos, I can't comment on how appropriate they might be. I'd caution you to opt for a larger container rather than a smaller one - if you are using a high quality potting soil, then excess soil surrounding the rootball is not a worry and you also won't need to root prune or repot as frequently. Anything in a container will need routine fertilizing as well. I dose all my containered JM's with a slow release pelletized fert (Osmocote) whenever I pot up and at the start of the growing season and that typically will take them through the summer. I will also sometimes use a water soluble fertilizer to supplement if the summer is dry enough or hot enough to prompt heavy watering. This is because every time you water a container grown plant you pull out or leach some of the nutrients from the soil and these must be replaced for strong health growth. So if you pay careful attention to 1) the potting soil, 2) proper fertilization and 3) adequate watering/irrigation, you should do well with growing your JM's in a container. PS. please do not shorten the name to "jap" - that is considered a pejorative term and has the potential to be insulting. If you need to abbreviate, JH is the accepted terminology or just spell out Japanese maple. Thx