Generally, they'll look best if you keep them on, unless they die off naturally through being shaded out by higher branches. So timing is if / when each branch dies.

But if you really want them with that utility pole look, then it doesn't really matter when you do it - the week before christmas is as good as any and provides greenery for use in the house. Don't cut off more than a fifth of the live crown height in one go (i.e., for a 5m tall tree, don't cut off more than the lowest 1m of live branches).

Resin

you need to think about two things...

first .. a mistake i made.. determine which you might not want in the next decade ... like the ones too close to the house ...

i had 6 of these pretty little pines around a deck, just like yours .... when i moved in ... and i should have taken them down since at this size they are pretty easy to do for free ..

10 years later i spent $1000 to have them taken down since they were repeatedly attacked by snow and ice load and threatened the house ...

these are forest trees.. and frankly should not be within about 40 feet of the house.. growing at 3 to 5 feet per year.. they can quickly overwhelm a situation ... and being so soft wooded.. they just become problematic ...

so start with that decision ...

now.. as resin noted.. i dont really understand why .. but if you want them pruned up.. all the power to ya ...

in spring.. resin flows [the trees.. not the guy above] ... and if you cut when its flowing.. you can get a lot of bleeding sounds .. and frankly.. cover yourself in the goo ...

so i would suggest you simply avoid that time of year... now .. or from about mid summer on.. should help you avoid that ...

and finally .. spend the money to buy a good saw ... it will make the job so much easier ... check out the link .. with its double row of opposing sharp points .. and on pine.. you can most likely go thru a 2 inch branch in 2 or 3 swipes.. once you master it ...

all that said.. do you know the proper way to cut a branch off???

good luck

ken

Here is a link that might be useful: link

BTW ... there are many fine non felco saws out there... it just made searching for the reference much easier ...

its the folding so it can be stuck in your back pocket.. and the double opposed sharp points that are the key ...

though with the shear amount of cutting you have to do... buying a quality tool probably will make a difference..

my felco hand shears are going on 25 years old.. nearly indestructible ...

ken

I'd ask if they were planted for windbreak. If so, then no time is a good time to prune off lower branches. If they were planted for a screen, no time is a good time.

But if aesthetics and function are not issues, as Resin said any time during dormancy. And make proper cuts, esp for that species.

Dan

I would do it between now and March.

Most pines planted close together / in a forest setting will lose their lower limbs within 15 yrs. Eventually the lower limbs will die due to lack of sunlight and act as a source of decay/rot in the main truck. A clean cut now will allow the tree to heal itself before decay sets in and/or the lower branches get too big to heal over quickly.

If it were a spruce/fir, it would be a different story. Google pine forests pics and you will see almost all mature pine forests lack lower limbs. By pruning now, you are preventing a potential source of demise of the tree.

Although not the natural way pines lose their lower limbs, a decent chunk of forest trees eventually die due to rot/decay/insect issues that initiates from dead limbs.

Here's another idea. You might be able to cut down every other tree to give more room for half of the trees to develop into a mature size.

"Eventually the lower limbs will die due to lack of sunlight and act as a source of decay/rot in the main truck [???]. A clean cut now will allow the tree to heal itself before decay sets in and/or the lower branches get too big to heal over quickly"

Not true. The tree seals off dead knot wood with resins, preventing any decay in the knot from entering the stem wood.

"Google pine forests pics and you will see almost all mature pine forests lack lower limbs"

No-one prunes the dead branches off them - if your above statement was true, these mature pine forests could not exist, as they would all have died off long ago from rot/decay etc. getting in through their numerous dead branches.

Resin

in spring.. resin flows [the trees.. not the guy above] ... and if you cut when its flowing.. you can get a lot of bleeding sounds .. and frankly.. cover yourself in the goo ...

==>>>> typo correction ... bleeding WOUNDS ...

not bleeding sounds.. lol ...

ken

'Zounds! ;)
I just thought you were being archaic, Ken.


Josh

This particular spp of pine in the olden days - before that area was clearcut 3x - used to leave limbs to help ladder up flames to release the serotinous cones for reproduction. One strategy, not the only strategy, but those with land looking to protect against fire may want to limb up to prevent laddering. But it depends upon what the trees were planted for, so without additional information everything here is a guess. Except pruning in winter of course.

Dan

There are technical papers on preventing tree decay/rot via pruning. Below is a cut from California's State tree/ag website.

I thought it was obvious to most folks that forests aren't manually pruned and all trees don't die from lack of pruning, but it is just another factor that could lead to trunk rot and early decline. You will not find a mature pine forest that has pines with limbs to the ground. So... either prune now during the appropriate season or let nature do it down the road and risk potential threat of rot issues. If they are not in a forest setting, it is a different story.

MANAGEMENT
Wood decay is usually a disease of old, large trees. It is very difficult to manage, but a number of factors can reduce the risk of serious damage. First, trees should receive proper cultural care to keep plants vigorous. Minimize wood decay by protecting plants from injuries. Properly prune young trees to promote good structure and avoid the need to remove large limbs from older trees, which creates large wounds.

John, I really can't follow your reply. Jack pine is fire-dependent and don't self-prune their lower branches until they are about 1/3-1/2way into their lifespan.

That is: fire is very common in jack pine stands and part of that is not because of the thick underbrush in such stands (the opposite is true), but because these stands commonly have lower branches that help ladder fire into the crown.

The 10-y.o jack pines in the OP most likely have persistent lower branches, some of which may have leaves on them.

Lastly, it is very common practice to prune lower branches, esp in pine plantations in the south. Standard. I have loppers I found that a crew left behind in a private Doug-fir plantation where I used to hunt mushrooms in Western Washington State (no I'm not divulging where!).

Dan

To make it simple there are two options:

Prune now and have a clean look or let nature run it's coarse and let lower branches die and hold on for a few years in a dead state. There is the chance the 2nd option could eventually lead to potential issues with trunk damage/decay.

20 yrs from now they will look fiarly similar either way. If near a house, most people don't like the look of dead branches holding on the lower limbs for several yrs before they eventually fall off naturally.