There is one plant about which I’ve receive more emails and questions than any other in the past 38 years. It’s Autumn Blaze maple, and inquiries have far outpaced even questions about the best time to transplant rhubarb.
The questions of course don’t address Autumn Blaze maples that are doing wonderfully. They’re about Autumn Blaze that are doing poorly.
Autumn Blaze maples have name recognition and have been widely planted with good reason. It’s one of the few trees people mention by variety name. The fall color is strong and vibrant.
But they’re having problems:
- Iron chlorosis, a yellowing of leaves causes by the tree’s inability to absorb naturally occurring soil iron, has been difficult to overcome. Iron products should be applied. Sometimes they’re successful, sometimes not. Sometimes ongoing, constant applications are needed. Whether the trees will need applications of iron continually throughout their life is unknown. The variety is too new to know what long-term needs in our area will be.
- Even young Autumn Blaze that looked beautiful in the fall of 2016 suffered major branch dieback during the winter of 2016-17, with large portions of dead branches failing to leaf out in spring 2017. The complete answer to why isn’t known, but is probably a combination of borderline adaptability, soil incompatibility, winter injury, herbicide sensitivity, planting depth and weather variations and growing conditions causing incomplete fall “hardening off” leading to tender branches being winter-killed.
- Maples as a group are thin-barked, especially when young, making them susceptible to winter bark injury and injury from mowers and trimmers. Tree wraps can help with the winter injury. Mulch around trees to eliminate mower/trimmer damage.
- Sometimes Autumn Blaze can be growing fine for a number of years, and then be hit with dieback.
Here’s a puzzle: How come one Autumn Blaze maple will be growing beautifully in one yard, and a block away another is dying? This is commonly occurring, sometimes even within the same yard. When homes are constructed, major soil excavation takes place. Topsoil is stripped and piled as is subsoil. When soil is replaced after construction, there can be pockets of poorer soil in which a tree might happen to be planted. The soil has been greatly shuffled around, excavated and relocated.
So, should Autumn Blaze maple be planted by us homeowners? Here’s a suggestion: Autumn Blaze seems to either do beautifully or do poorly – a roll of the dice. In a spot where we would definitely like a newly planted tree to survive without a greater risk of needing to replant, maybe other non-maple choices are better. If we have a secondary spot where we would like to enjoy the glorious colors of Autumn Blaze and are willing to take a chance, then go ahead. If it makes it, great, if not we won’t be crushed. Save Autumn Blaze for special, non-necessary locations.
Oh, by the way, Autumn Blaze and similar maples do beautifully in the naturally forested soils of Minnesota and eastward. West of that region, in soils of prairie origin, maples aren’t as naturally adapted. And that’s the crux of the problem.