Need help with your arbs? Thank C.C. for emailing to us:
We have two trees or bushes on the side of our garage. We have been told they are cedar. They are 10 to 15 feet tall and are in desperate need of pruning but we have no idea what we are doing. Can you give me some direction? - C.C. -
Late winter is a good time to prune arborvitaes, to catch them before they begin growing, remove some tips and thereby "reprogram" remaining branches' pecking order. The result is that limbs further in and down will do more growing than they would have otherwise.
C.C.'s brief question led us down several side tracks. The simple answer is here, but please do look also at Arb cut in time, Arbs cut hard and Arbs long recovery. The photos in those other articles can help you decide how far to cut, anticipate the rebound, and then keep these trees from getting out of hand again.
These are plants that can reach a point of no return. Keep an eye on their size, uniformity of greenery, and density.
Notice if your arbs have reached the maximum height or width you can allow.
Yes? They have just reached their limit? Cut them! See Arb cut in time.
In cases like C.C.'s, the trees are too big already. The check becomes, how big do you want the trees to be and will they tolerate being cut back that far?
For instance: If you want an arborvitae to be 3 feet shorter and 2 feet narrower, now's the time to look inside. See how deep the greenery extends inward. If there's green within the outline you imagine -- lacy green branches or green buds -- then you're good to go. You can cut back.
Chop that plant back to the line you drew. Then cut back further on any branch that's wood-only. Don't leave any woody stubs . Cut everything back to a leafy bud or to a side branch that has leaves at its tip.
Is one side or the lower half becoming thin?
Arbs are sun lovers that we often relegate to shady places. They lose density, especially on the north side and where their own top billows out wider than their feet. Thin areas can reach a point of no return -- all the greenery languishes and falls from those branches and cannot be regrown. Don't let that happen.
When you see thin places in an arb, thin the top or the opposite side or prune overhanging trees. The objective is to let more light reach down or through to the thin area.
We don't trust our memory for spring check. We take photos as a regular part of garden care, and review them each year.
Is the plant becoming hollow? If so, cut back every 4th or 5th branch to let light reach remaining interior leaves and buds. If you don't begin doing this regularly, you can kiss that plant good bye. When a plant has a lot of wood (starch users) and relatively little leaf (starch producers), it begins to starve. Weakened, it falls prey to its insect pests, diseases, and has less tolerance for marginal growing conditions. As it loses ground to these problems, it thins even more.