The Smoke tree (Cotinus coggygria) is a multi-stemmed tree that is also often grown as a shrub. It grows approximately 15 feet in height and 10 feet in width. In June and August the tree turns a smokey pink in color that is quite unique in the landscape. Long panicles that sport tiny flowers are what gives the tree the appearance of being pink smoke. Foliage is a dark purple or mint green in color that is outlined in red. The fall foliage color is a striking overall red or purple color.
The smoke tree comes in several varieties. The most commonly seen variety has dark purple leaves that are outlined in red but the tree also comes with green foliage. The fall foliage on a green leafed smoke tree first turns yellow, darkens to red and finally ends in a breathtaking dark purple. The entire fall display on both green leafed varieties and purple leafed varieties can last up to a month. The smoke trees with the green foliage often lack the illusion of a smokey appearance from the panicles of blooms that the more common purple foliage offers in spring and early summer.
Location And Soil
Plant the smoke tree in a location that offers full sun to partial shade. Full sun deepens the purple leaves on the purple varieties. The full sun also aids the tree in sporting outstanding fall foliage colors.
Smoke trees can thrive in virtually any soil conditions but for ideal growth mix 50% peat moss with 50% garden soil when planting. This will give the tree an ideal start. Do not fertilize when first planting. Wait until the tree shows signs of new growth. Once new growth appears use a 10-10-10 fertilizer mix. Newly planted trees may require staking in areas that receive high winds. The tree has a fibrous root system and can easily be transplanted even when quite large.
Fertilizing And Watering
Use either an 8-8-8 fertilizer or a 10-10-10 fertilizer on a smoke tree. Apply fertilizer in March, April and May. Spread fertilizer 18-24 inches out from the base of the tree all the way around. Water the fertilizer thoroughly after application. Maintain moist soil conditions for the smoke tree. The tree should never be water-logged but it will enjoy being moist. The tree can withstand severe drought conditions when necessary.
In tree form the smoke tree rarely requires pruning. To maintain a shrub like appearance prune the tree in early spring. Cut the tree entirely down to one or two buds at the trees base. If the tree is being grown as a tree form then only remove dead limbs during the spring or limbs that are crossing.
Powdery mildew often presents a problem for purple leaf smoke trees. Plant purple smoke tree varieties in full sun to lessen the chance of contracting powdery mildew. If the tree is struck with powdery mildew then purchase sulfur, dinocap, fenarimol, triadimifon or benomyl fungicides. Apply according to the directions on the label for control.