Japanese Maple trimming

Hello,
I have a Japanese maple that has doubled in size in about 20 months. I live on the central coast of California and the growing season is very long here.
There may be many sources for this type of information and if there is please point me there, but I'm interested in trimming this tree back. For the area it is growing in, it is becoming extremely large. So I'd like to trim it back and was wondering how much to trim it back while still being safe for the tree and when to do so.
I didn't plant it - I "bought" the tree when I bought the house. It's beautiful and I wish to keep it healthy but managed.
Thanks,
Djay
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Unless it is a very young or immature tree, it is highly unlikely a Japanese maple would double in size in only 20 months - they are notorious for slow growth even under ideal conditions, typically taking 25 years or more to reach a mature size.
Rather than attempting to maintain a reduced size in its current location (never the most desirable solution), it may be preferrable to relocate the tree to a more appropriate spot where it can be allowed to grow without interference. If the tree is too large to consider moving, then I would consider hiring an arborist that specializes in pruning J. maples. One of their best features is a sculptural growth habit, specially with a mature tree, and excessive or improper pruning can really negatively impact the tree's appearance. Nothing is more unattractive than a whacked at J. maple.
Most maples and Asian maples in particular bleed sap extensively if pruned at the wrong time. I have not encountered permanent damage to trees if pruned at the wrong time of year, but it can set them back and stressed trees are much more prone to various disease pathogens. Pruning is best done when the sap is not actively running - midwinter (December/January) or in early summer (June, at least in my climate).
I'd visit a good garden center in the area that sells lots of J. maples and get their recommendations for qualified arborists. Watch carefully as they thin or head back and shape the tree and learn how best to do this yourself for the future to encourage correct growth and to avoid disfiguring a wonderful landscape asset.
pam - gardengal

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Pam:
We have an Acer palmatum "Bloodgood' on either side of our driveway entrance, which are between 12' - 15' tall and very thickly branched. I think they are gorgeous unpruned with branches coming all the way to the ground in a layered look. My wife wants to prune out the bottom branches so that they have more the appearances of trees rather than shrubs. So far I have won the dispute, but..... They have ample space to grow to any size without interfering with anything. She thinks the bottom branches make the them appear messy and overgrown.
Do you think I should give in and let her turn them into trees, or should I insist they keep their J. maple appearance?
Thanks..... John
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B & J wrote:

Don't give in, Japanese Maples look their best when left to their own.
--

Travis in Shoreline (just North of Seattle) Washington
USDA Zone 8
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Hi Pam,
I think djay may have bought a young tree. Japanese maples often put out relatively long shoots of a foot or more and when the tree is young it can certainly "double" in size. I have an Umegae that was only about a foot high last year and this year it sent out two new branches that reached almost a foot...doubling its size. I think this is what djay experienced.
Layne
wrote:

snip
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That close to what happened Layne.
I bought this house in January 2004 with the JM already in place. I have a picture of it because I was taking a bunch of pictures of the new place inside and out. It was about 6 feet tall then - but the leaves had mostly dropped for the winter. Now looking back at my original post, I think my "double in size" comment was more describing the volume of the tree. It's probably 8 ft tall now but much more volumes (likely to additional growth and now it's August and the leaves are there).
The problem is that it is encroaching on the walkway on the side of the house. I wanted to "thin" it out and remove the portion that is overhanging the walkway (about chest level) without hurting the tree.
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http://www.treesaregood.com/treecare/pruning_young.asp http://www.treesaregood.com/treecare/pruning_mature.asp
Thinning is commonly practiced, rarely advisable. Trees need interior growth to increase branch taper/strength. Also, leaving interior branches gives you something to cut back to if there is breakage or pruning in future.
Cut the stuff that's in your way back to a branch collar. What you leave should be at least 1/3 the size of what you remove. Don't cut anything else green unless it is diseased, damaged, or rubbing another branch. Pruning can easily go wrong, but a little common sense will take you a long way. Just go slow, make proper cuts, and don't do too much all at once (officially, don't remove more than 1/3 the tree at a time; practically, avoid removing more than 1/4 if you can--and don't do either more often than once every couple of years). If you follow these guidelines, trees can be very forgiving of your mistakes while you learn from them.
The nice thing about pruning your own trees is that you can make one cut a day, one cut a week, or one cut a month; if you make mistakes, they will have a minor impact and you can do better next time.
k
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wrote:

Treedweller,
Thank you for the advice. I will remove a portion of the branch that is giving me problems and not much else. I'm sure glad that this forum exists so that the knowledge of many can be shared so easily!
Djay
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Hi djay,
Treedweller's advice is very good and should be followed. FWIW, I usually prune in the winter after all the leaves have fallen. This allows me to see the tree's branches better. Light pruning (less than a 1/3) can be done any time of the year. Heavy pruning (more than a 1/3) should be done when the tree is dormant. Deciduous trees need their leaves to produce enough nutrients to tide them over for the winter and push out growth in the spring.
Layne
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wrote:

Again thanks Layne,
I will live with the "offending" branch for the rest of the season (for me that's another 3 months) and trim it in Dec or Jan.
Thanks again! Djay
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