Need input on filtered shade tree options

[MBCGardener]

We have a Chinese Elm that is rotting from the inside out and will need to be replaced in the next few years. Shrubs and plants underneath include many rhododendrums, azaleas and boxwoods. They have all done very well with the filtered shade from the Chinese Elm. Can you recommend a tree that would provide similar filtered shade? A landscape architect who helps me out has suggested an Autumn Blaze Maple but I am a tad concerned it will be too dense and not allow enough light through for the other plants. He says I can thin the tree branches to addess density. Would appreciate thoughts as I love the flowering shrubs. A benefit of the recommended Maple is that it is a fast grower, which ois something else we probably need.

[Sillyheart]

I would suggest a sunshine locust tree. The new leaves open a nice yellow and then turn green later. The tree gives dappled shade. It looks so nice because it is green throughout the tree and these nice yellow new leaves on the end of all the branches.
Happy Gardening

[rainbowgardener]

You didn't say where in the world you are gardening; it makes a difference.

Mimosa is a very pretty tree, with pink flowers that hummingbirds like, easy to grow and drought tolerant. It does give the kind of dappled shade you are talking about, but is only cold hardy to zone 6. This site has a map of where in the US they grow, which is pretty much everywhere but northern new england and the plains states:

https://www.fast-growing-trees.com/Mimosa.htm


I think willow trees might be another dappled shade choice.

[MaineDesigner]

I want to offer a strong second to rainbowgardener's post. Gardening/landscaping, done well, is extremely location specific.

I'm very dubious about the Autumn Blaze as it has several qualities that don't recommend it for this application: it tends to have wide spreading but relatively shallow roots, it is something of a moisture hog and it casts relatively dense shade. To be fair, however, Ulmus parvifolia is not that different with regard to these qualities.

Unfortunately Mimosa is on the invasive plants list in several states.

Don't get me started on the subject of typical LAs and their lack of depth of plant knowledge although there certainly are exceptions that try the rule.

[MBCGardener]

Thanks for replies thus far. Responding to replies, we live in Kansas CIty whicvh has very hot summers (90s to occassional 100s) and realtively cold winters (30s to below freezing) with winters going from Nov/Dec through Mar and summer heating up mid- June throughj end of Aug. The tree is on the south side of our house. We have sprinkler systems installed. Does this in fo help? Also, does the Sunshne Locust have thorns?

[Sillyheart]

No, a Sunshine locust does not have thorns . It should do well there because your climate is much like ours here near Toronto, ON, Canada.

[microcollie]

I have a mountain ash (sorbus aucuparia) in my yard with several shrubs and shade/part shade perennials under it...sounds like a similar situation. They're beautiful trees, fragrant white flowers in spring followed by bright orange berries which last until the cardinals take them (another plus...it seems to be one of their favorite foods). Take note...mountain ash is a generic term and can refer to a handful of different trees. Look for European mountain ash

They're pretty fast growers mine went from 6' to 40ish' within the 8 years it's been in my garden.

I'd shy away from any kind of maple. If you have to prune limbs to let light through, then it's not the correct tree for your setting.

[MaineDesigner]

I've worked on projects as far west as you are but not nearly as far south. Most of my experience is in the northern tier states so please keep that in mind. I meant what I said about gardening/landscaping/horticulture being extremely location specific.

The Honeylocust, Gleditsia triacanthos var. inermis, has some aspects that strongly recommend it: it casts light shade, it is moderately fast growing, its roots system rarely causes problems with adjacent plants and fall clean up is easy. Unfortunately not all the news is quite so positive. It is vulnerable to a host of insect and disease issues and tends to be quite short lived. In my experience it is rare to see specimens more than 25 to 35 years old and in worst case situations they may only survive 15 years. I like 'Skyline' or 'Shademaster'. If you want one of the chartreuse leaved selections opt for 'Summergold' rather than 'Sunburst'. All these are thornless and if I recall correctly produce few, if any, seed pods. It is possible that Honeylocust doesn't cast enough shade for your rhododendrons in your hot summer climate.

Most of the Mountain Ash, Sorbus, species except Sorbus alnifolia (Korean Mountain Ash) are every bit as short lived and troubled by insects and diseases as Honeylocust but, in my opinion, have even less to recommend them in this situation.

I think an oak (but probably not Quercus palustris) could be a good choice although the tendency of some species to hold leaves late really annoys some people. My maybe list would include Sophora japonica, Cladrastus kentukea or possibly Gymnocladus dioicus. In contrast to the Honeylocust these trees are generally regarded as "messy" but I believe other virtues may outweigh that in the right situation. Ginko biloba might also be worth consideration with the caveat that they go through a long, rather awkward looking adolescence before they start to look handsome. The Sophora has the fastest growth rate among these but it is semi-fussy about culture. It demands good drainage.

I urge to seek local, or at least regional, expertise. Ideally someone with a horticulture education rather than most LAs.