Choice of tree
I have narrowed my choice down to three trees for a south facing section of lawn. I would like to plant three along a section that is 13' wide and 56' long. I can make the width up to 19' if needed. My three choices are: 1. Acer grandidentatum (bigtooth maple) 2. Cladrastis kentukea (American yellowwood) 3. Corylus columa (Turkish filbert) Which one would you recommend? Do I have room for three? Should I plant all three the same? Do I need a width of 19'? I plan to have mulch in the entire section. The south side borders the street and the north side is grass, then a walkway, then a mulched area with an Austrian pine and then the house. There are two blue spruces in the same section on the east side and a sidewalk and grass on the west side. I live on a corner lot that is roughly 19,000 sq.ft. In SE Denver. Thank you. Stephanie
Denver County Colorado
The Yellowwood (Cladrastis kentukea) is an unusual selection for Denver, and, while showy and fragrant in late spring, you may have trouble sourcing it. For that reason, I'd put it at the bottom of the list. There is a nice one at Denver Botanic Gardens along York Street if you're interested in seeing a nice one.
As for the other two, the Turkish Filbert (Corylus colurna) eventually will be a medium-sized tree (40'-50'). It has a distinctly formal habit, and is touted to do well in hot summers and cold winters. The catkins are ornamental over the winter and the tiny flowers in late winter are fascinating. There's not much in the way of fall color. The Bigtooth Maple (Acer grandidentatum) is probably the smallest of the three, and is thought to be drought tolerant - for a tree - once it's established. Its claim to fame is its autumn foliage which turns shades of yellow, orange and rosy red. Which you choose depends on which of these features sound best to you.
In terms of spacing, be aware that Denver Forestry rules govern trees in the city right of way. They require trees be 30' from the curb at intersections, 20' from stop signs, and 25' between ornamental trees. Go to their website for details.
Use wood, not a rock, mulch. A large expanse of rock mulch in a south-facing site adjacent to a street will be a very hot, stressful environment for your new trees and should be avoided.
Thank you very much. I'll check out the Denver Forestry website.