Fall’s cold and wind have obliterated most of our foliage, or at least relocated it from limbs to patio and ground. But one small tree hangs in there with a full canopy of greenish-burgundy leaves. The smoke tree (Cotinus coggygria) is one of my favorite trees for fall and year-round color.
In fact, our tree held on to many of its crispy gold leaves all winter last year. Then in spring, new green foliage emerged. But the tree’s seasonal colors, which changed from greenish blue to deep burgundy or purple, to gold, are only part of its charm and drama. It also sends out puffy seedheads that resemble — and smell like — smoke. The pinkish seedhead clouds, which give the tree its name, usually appear in mid-summer here, but the timing varies depending on conditions. Regardless, they remain attractive for weeks.
Caring for smoke trees
So I love how smoke trees look, but here’s what really seals the deal for the New Mexico xeric gardener: The Sunset Western Garden Book says the tree is “at its best under stress in poor or rocky soil.” OK, I have lots of that. And it can tolerate some drought. When temperatures hover above 90 degrees F, a deep water every couple of weeks helps get it through the hottest part of summer.
The other attractive feature of smoke trees for xeric gardens is their versatility. While the trees are starting, gardeners can shape them into small bushes or short trees, depending on the location or preferred look. C. coggygria typically has multiple small trunks. Ours was trained to a small tree shape, which still works well in a large rock garden because it only grows to about 15 feet high at a rate of about a foot a year. You can train it for light shade, or as a low, bushy foundation plant and home for birds.
Until established, smoke trees might need a little more water and application of some slow-release fertilizer in the spring. But since it prefers poor soil, the tree needs no more than that once it’s on its way. And if you’re shaping the tree, Judith Phillips recommends that you cut back or stop fertilizing once you begin those pruning cuts. You can add some mulch to save water and cool the roots, but since the tree loves rotten soil, there’s no need to add organic matter. And if you add mulch, be sure to keep it away from the trunk. The tree can thrive in full sun or partial shade. Suckers will begin to show up around the base of the trunks; you can just pinch or cut them off to send energy back up into the main trunks.
Smoke trees are subject to verticulum wilt and leaf roller mines in early summer. We also had to remove about 40 io moth caterpillars from ours this year because they were stripping entire branches. But those stinging nasties were making their way around all the small trees near the house.
More about smoke trees
The C. coggygria varieties do fine in USDA zones 5 through 8. The purple varieties look great on their own or as a bush planted near a silvery conifer or perhaps with an artemesia or gray santolina planted in front of them.
The C. coggygria is sometimes referred to as the European smoke tree. Another species of smoke tree called C. obovatus is called the American smoke tree. It is slightly larger and has bigger leaves, but has similarly striking seedheads. The Dalea spinosa (Psorothamnus spinosus) also is called a smoke tree. It is a grayer tree native to Southwestern low deserts.