Around June-July is supposed to be a fairly good time, too late in the year for spring sap flow, but early enough in the year for the tree to get a good start to the wound occlusion process before the winter.

Resin

if a sugar maple is bled intentionally for the sugar ...

then in theory ... i dont see why bleeding due to pruning would be any different.. simply from a logical deduction ...

i am of the mind [for what that is worth .. lol ] .. that pruning is done when i have the time.. or the money to pay to have it done .. or to repair storm damage ...

yes.. there is always a PRIME time to do it ... but you know.. sometimes you just run out of options .. and have to do it when the mood strikes ..

can you please explain why you think your trees need thinning.. and please tell us that it does NOT involve TOPPING .... what is your goal here .... are they over hanging the house....

personally .. i never contemplated thinning of a mature tree .. because they need it... they are fully capable of taking care of their own growth patterns ... so i suspect there is some other facts we might need to know ...

good luck

ken

"if a sugar maple is bled intentionally for the sugar ...

then in theory ... i dont see why bleeding due to pruning would be any different.. simply from a logical deduction ... "

The difference is in quantity. Cutting off a large (or several large) branches would lead to substantially greater sap loss than harvesting for maple syrup.

Cutting off just small branches won't hurt, though it will still leave an unsightly wet stain running down the trunk with the likelihood too of the sap being colonised by sooty mould fungi making the stain look even nastier and more persistent.

Resin

........but, but, but.......despite this "bleeding" of sap, and despite the possibility of there being some temporary discoloration on the trunk from doing so, right now is THE best time to prune maples, oaks, elms, or pretty much any other woody plant.

I have personally pruned thousands of maples, including several today, during this time of year. No harm will befall them from doing so.

+oM

Hey, +om, is the sap running up there yet?

tj

I just cut down one large rotting silver maple and found tons of sap still flowing all over it. Some branches ended up so sticky it felt like I was hauling around christmas trees lol.

Also just cut a low branch off a 12 foot red maple. Plenty of sap came out. Enough any early spring bugs would be coated and killed by it, and enough the wound has a light coating over it. I thought that was a good thing because it was the tree's natural defense against infection?

Optimal timing does vary with kind of tree or shrub. Woody does not universally = prune in winter. Some, such as orchard apples and wisteria vines may be thinned in winter and headed back in summer.

thanks all....to answer one of the posts...I'm thinning out a bit to allow more sunlight to filter onto a perennial garden nearbly. Since the weeping doesn't harm the tree, I'll probably trim in May before full leaf out. It is much easier to take down branches without the leaves.