Native to the Pacific Northwest, vine maple grows as an understory tree in old growth forest and as one of the first trees to colonize open slopes. As part of a tended landscape, vine maple often reaches 10 feet tall with a spreading crown double that in diameter. The clustering small trunks grow twisted and reach out horizontally, rooting where they touch the ground. Pruning transforms this thicket into a sturdy, small tree with a gnarled and twisting trunk. In natural conditions the average mature height of vine maple may be 25 feet. The record height for the species is 62 feet.
When growing vine maple from seed or from a cutting, allow the plant to establish itself and show vigorous growth before pruning. In the second year select the strongest stem and use pruning shears to cut off other shoots just above ground level. Remove the sucker shoots as they form.
During winter dormancy, lift the shape of the tree by clipping small branches back to a main junction if the branch tips dip near the ground. Vine maple naturally forms, spreading thickets by rooting at branch tips. Thinning the small branches of the limbs keeps the direction of growth upward rather than sideways.
If the main trunk begins to lean, the tree may need to be staked upright for a season or two. Convoluted growth is part of vine maple's natural character and contributes to its unique appearance as it ages. With a single trunk selected, the tree soon acquires the vertical habit. Place some padding around the trunk before lashing it to the support stake with twine. Tie the twine loosely to avoid strangling the tree.
With limb loppers or a pruning saw, remove smaller lower limbs from the trunks of maturing trees. If the tree forks, preserve the balance between the two sides of the vine maple by clipping branches from the dominant side. Thin the canopy by cutting back smaller branches to their junction with the main branch. Clipping branch tips creates denser foliage but disturbs the natural shape of the tree.
Use limb loppers to trim out storm damage or crossed branches in the upper canopy. The vine maple should require less attention as it matures. Continue to trim back lowering branches to keep the canopy above head height.