The city of Toronto planted a bare root Red Maple tree on the boulevard in response to my request for a tree that turns brilliant vibrant red colour in fall. Is there any way to tell what Red Maple cultivar it is? The colour is quite poor in fall, yellow, brown some red.
Thank you for planting a tree on the boulevard! Urban trees help reduce stormwater runoff and decrease the urban heat island effect by providing shade and cooling the immediate vicinity through evapotranspiration.
I’m sorry you aren’t pleased with the leaf colour in autumn. Unless there is a tag on the tree, there really isn’t a reliable way to determine the exact cultivar of the Red maple (Botanical name: Acer rubrum) that was planted. If the tree is planted on city property, have you contacted the City to ask what type of maple you have on your property, or have someone look at the tree? From the City’s website: “Other maintenance, such as pruning, fertilizing, or staking, is performed by the City when needed. The City of Toronto maintains trees located on the City-owned road allowance, including proactive inspection and maintenance. However, if tree requires additional maintenance, beyond proactive maintenance, a service request may be submitted through 311 Toronto to have the tree inspected for appropriate action taken by Parks, Forestry and Recreation.”
I can think of three possible reasons why the leaves are not a bright red.
- The City may have determined that a Red maple wasn’t suitable to plant in that location and substituted a different maple. Please see this information from the City’s website regarding tree Species Planted on Streets. If you read the descriptions of the different maples, you will see that the Red maple is not suitable to plant in all urban locations. Other maples that turn orange in autumn and appear on the Toronto Street Tree Guide are: Sugar maple (Acer saccarum) and Autumn Blaze Freeman maple ( Acer x freemanii ‘Autumn Blaze’). The Autumn Blaze Freeman maple is a controlled cross between a Red maple and a Silver maple. More information on this tree can be found here.
- The tree is a Red maple but may be under some kind of environmental stress. You don’t say when the tree was planted. If it was in the past year or two, the tree may still be trying to recover from the stress of being planted. Leaf scorch may show up in the summer as yellowing leaves with brown around the edges. The Morton Arboretum has a very good description of symptoms, causes and care. Are you providing adequate water for the tree? New transplants will require more water while they are becoming established. Has the tree been properly mulched? There should be a doughnut ring of mulch at least 2-3″ deep and a diameter of 4′-6′ around the tree. The mulch should not touch the trunk of the tree. Please take a look at “Planting a Tree for Life: A Toronto Master Gardeners Guide” for more detailed information on after care.
- Red maples grow best in slightly acidic soil. If your soil is very alkaline, it may inhibit the ability of the tree to uptake certain micronutrients. A post from the Piedmont Master Gardeners states the following: “Alkaline soils (those with a pH above 7.5) usually cause leaf chlorosis (a yellowing of the leaf blades, often with pronounced green veins). Abnormal yellow color in maple trees is frequently associated with nutrient deficiencies, particularly manganese. Manganese nutrient deficiency leads to nitrogen deficiency, resulting in poor chlorophyll production and stunted growth. As soil pH increases (becomes more alkaline), the ability of the red maple to take up manganese decreases. If high pH is verified by a soil test, you can lower your soil’s pH (make it more acidic), by applying elemental sulfur or acidifying fertilizers.” Here is a link to the full article which also lists popular cultivars of Red maples. Never apply acidifying fertilizers without first having your soil tested. It is also extremely difficult to change the pH level of soil and you would need to reapply an acidifier every year.
I hope your tree grows successfully and provides you with beauty in all seasons.