You can prune a Japanese maple anytime you want. Upright or weeping. It doesn't make a difference. Start at the bottom and inside and work up making an umbrella as thin as you can without allowing too much sun on the trunk. Too much sum will sunscald the trunk. On the sidewalk side you can make the umbrella a little higher to make more room for walking.
Most Laceleafs are planted too close to something. They get larger than most people realize and do it faster too. They can be transplanted to a better location when dormant. That's what I would do.
I grow a lot of Japanese Maples. The link shows one of mine. |
Here is a link that might be useful: Pruned Japanese Laceleaf Maple
