Anne Taylor, certified arborist and garden designer. We'll see if I can get them back into shape so my fuchsia can continue to intertwine with the chartreuse leaves and velvety stems.
Anne's advice on pruning sumac:
• Don’t prune more than 1/3 of the plant away at any time. Removing too much wood can cause extra stress on the plant.
• If you are drastically pruning the shrub to get it back in to place or shape, fall and winter are a good time to do this. If you are pruning a few branches for shape, summer is a good time for that.
• When pruning, start with removing any crossing branches and dead branches then continue removing branches to get the shape you are looking for. It is best to prune both sides, going from one side to the other, and back and forth so the shrub does not become lopsided (unless that is the look you desire).
• Make the cuts where the branch attaches to a stem. Do not cut the branch in the middle! You will get strange growth that way.
• Sumac branches that touch the ground will root when they rest on soil, so if you do not want this, prune to keep the branches from touching the ground.
• Sumac shrubs tend to sucker. The only thing that can be done about this is to keep it in a container, or remove the suckers by cutting them, as they pop up around your yard. Spraying Roundup or any other killing spray, will not prevent the suckers from growing and it can harm the mother plant, so don’t do it!
• Wear gloves and wash them afterwards! Sumac sap can irritate the skin. Make sure you do not touch your eyes because you could inadvertently get the sap in your eyes.