Pruning pines takes patience
I have a 5-foot Austrian pine in my front yard. When we first moved in, a landscape consultant told us we could trim the top with shears to stimulate growth, so I did that. It stimulated branching of the tree over the summer, but may have added a dense knot of growth that won’t look very good as the tree matures. My husband decided to trim off the alternate leader the next spring, which left one third of the tree with no limbs at the bottom. Additionally, I read that I should stimulate growth by de-candling the tree, which I did as well, mostly around the top. We now have a tree that is missing one third of its branches near the bottom, and the second round of growth, just below the top, has caught up to the top growth, resulting in a general horizontal line across the top of the tree. I think that I have probably mutilated this poor tree. Is there any hope it will ever have a beautiful shape?
Actually, you may be on the right path; it may just need a bit of time, proper application and perhaps a better understanding of the tree for things to work themselves out.
Trees that are grown from seed (like your Austrian pine) will have some natural variance in needle color, shape, growth rate, density and growth habit. Most Austrian pines will have dark green needles with a rounded, conical growth habit. They usually don’t form a completely solid outline but retain a bit of a “see-through” quality. However, there will be individuals that differ from this norm and are lighter or darker green, some that are broader and others that are narrower and more upright, and some that are extremely thick and dense and others that are thinner and more open. Those characteristics are inherent to the genetics of the plant. However, we can modify some of these characteristics to an extent through specific pruning techniques.
When I talk to people about a pine tree that’s a bit misshapen or thin, the first thing I’ll counsel is patience. All types of trees can sometimes go through an awkward phase when some parts grow faster than others, or they’ll go through a growth spurt that kind of knocks them out of proportion. Left alone, the tree will almost always work out those issues and shape up to be a beautiful specimen.
We can sometimes apply a bit of strategic pruning to shorten that awkward phase or minimize any shortcomings the tree may develop. I’m not a big fan of shearing on pines. If you want to try it, you can, but it’s very important to time the pruning carefully or you’ll end up with problems.
Each spring, when the new buds break, the shoots elongate and form “candles.” New needles emerge along the shoots; the shoot completes elongating and sets new buds for the next growing season at the branch tip. These new branches then harden off, changing from somewhat soft, succulent tissue to harder, woody tissue. The best time to shear is when this elongation is complete, but before the branches fully harden off. The time for this varies, but around here it’s usually any time from the end of May into the middle of June. Pruning much earlier or later than this results in smaller buds and spindly, weaker growth in subsequent years.
If you do shear the pine, shear the entire tree, not just a portion, or you’ll end up with that flat top you’re seeing. You’ll want to start to shear it into the shape you desire — that is, prune less at the very top and progressively more as you go down so you re-establish that cone shape. Be patient about this, too, it may take several years of progressively pruning the tree to bring it fully to the shape you want.
Doing this will thicken up the tree considerably, but unless you continue to do it, you can end up with a very thick section of the tree while the growth before and subsequent to it will be more open. You might consider using this method on your tree for a year or two to point it in the right direction. It’s also important not to cut the candles off too much. Taking just a bit off of the tip will help thicken the tree up while minimizing that short, dense, bushy growth.
I know the tree looks a bit lopsided now, but that should pass. The adjacent branches will grow into that area, filling it out in time. Don’t give up on it yet! Concentrate on giving it the best care you can — water it deeply but infrequently and fertilize it lightly in the spring with a slow release nitrogen fertilizer. You should start to see some improvement next summer, which should continue as time passes.