In fall, the increased length of the dark period (not day length, technically) pushes the plant toward dormancy. Chill seals the deal, moving the plant into deep dormancy. It's also chill that releases the plant from dormancy. After exposure to an adequate amount of chill units, the plant passes into a quiescent period, unnoticed, after which the onset of growth will begin as soon as temperatures allow. Usually, several days with soil temps above 45* is enough to get buds moving.

Throughout the year, the plant will be very responsive to photo-period - changes in the length of the dark period.

For keeping maples in containers attractive and growing up to their genetic potential, you'll need to shoulder some responsibility for regular root work and repotting, as opposed to simply potting up when the root/soil mass gets terribly congested. I'll link you to a thread I wrote about maintaining trees in containers over the long term. You'll find some pictures there, too.

Maples usually have an opposite leaf pattern, with successive generations 90* to the previous pair, a grow in a trifurcated branch arrangement. This is problematic for trees grown in containers, because when 3 branches converge at a single point, you can expect an unwanted bulge or swelling at the union. It's best to remove 1 of the 3 branches, even the tiny twigs, for the best looking trees.

Also, your trees should be pinched as the new leaves open. After the first pair of leaves opens, pinch out the center as soon as it can be done w/o damaging the lateral leaves. This truncates the branch and forces compactness.

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I posted the pictures so you could see I'm not a beginner at tending maples in pots, and that what I offered works when applied practically.

Best luck!!

Here is a link that might be useful: The trees in Containers thread .....

Thanks for your help, and wow those trees look stunning. Will my plant carry on producing leaves throughout the summer? If not, is it possible to trick the plant by putting it on a long dark cycle indoors perhaps 12 hours light and 12 hours dark and perhaps chilling it in a fridge for a month or two and then bringing it back up to temperature to replicate spring time? I'm hoping to bonsai it one day but need lots of growth first. I'm new to bonsai too as I'm sure you have guessed lol.

Also, my plant has an unsightly grafting scar, is there a way of tidying this up?
Thanks for your help

Your tree will continue to produce new foliage as long as it's alive and in the growth phase .... so, from the time it puts on its spring flush until it starts preparing to shut down for the winter.

You can't 'trick' the plant into behaving as though the nights are any length other than what they actually are unless you have complete control over photo-duration and can eliminate all sources of extraneous light. Just an observation - before you start trying to manipulate the plant in ways that might be considered severe, it's best to have a fairly clear picture of what results your actions will yield. Your tree will remain healthier and put on the most growth if you let nature's normal influence guide you in some important areas.

One thing is very important to the well-being of the plant - root health. How goes the root system, so goes the rest of the plant - generally. If you're serious about keeping your trees healthy, learn how much influence your soil choice has on the goal. There is absolutely no sense in fighting your soil for control of the plant's vitality. See the link below for more info re. soils. For container growers, the information at the link probably represents the largest step forward that can be taken at any one time.

In some cases, unsightly bulges and scars can be avoided by some foresight and judicious pruning. They can also be turned into features (containerized trees) by a little skillful carving to remove the bulge - the tree will heal. Not so much with grafting scars, though. If you start carving in that area, you can easily jeopardize the viability of the plant. If I purchase a tree with an unsightly graft union, I usually layer the top off above the graft - as long as the cold-hardiness of the roots isn't a consideration.

This is a maple that was layered off just above an ugly root system. You can still see the wire tourniquet. Note how attractive, flat, and symmetrical the root system is after layering:
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Al

I can keep control over the photoperiod if I wanted to as the plant is in a light tight area under lights, but I understand now that it would need the full summer to build up its resources to grow well. The idea of rushing through its phases has now been discarded as noobie over excitement lol.

If I layered above the graft wouldn't that compromise the good roots? Does the term layering mean to grow roots? I may be getting confused. I'm not 100% understood on the idea of grafting. In my case the foliage is beautiful, but would I be right in saying the roots from my plant are weak or have some other problem so a variety that has good roots has been used?

I'm no beginner when it comes to annual vegetables and fruit. But ornamental plants are completely new to me

Layering is a propagation strategy that effectively reduces or eliminates phloem transport. Photosynthate (carbohydrates) and growth hormones collect in the tissues above the layer and stimulate new roots to form. If you successfully layer a new tree off above the graft union, you'll have the new layer + the original tree, a twofer.

There are a number of reasons plants are grafted to understock - ease of propagation, cold hardiness, resistance to insects/disease, growth control .....

Al