That is a lovely tree.
The red leaves are early fall coloration, which suggests there is some stress to the tree. Stress can come in many forms, especially for a tree that is new to the site and is still establishing.
Correct planting and aftercare, particularly watering, is important.
How large is the tree? It could just be the angle of your photo, but it looks pretty tall, suggesting the tree was older, and was dug and balled and burlaped or caged, as opposed to growing in a pot?
Trees lose a large proportion of their roots when they are dug, which is stressful in itself, but you should check too, if you didn't plant it, that the burlap and cage was removed. (Some burlap has plastic fibers in it that don't biodegrade.)
This page from N.C. State will tell you more about your tree, but note that it says that this one can be difficult to transplant:
https://plants.ces.ncsu.edu/plants/cercis-canadensis-forest-pansy/
That said, your tree looks pretty well overall. 

Here is our page on tree planting to go over just to rule out anything that may be a problem: 
https://extension.umd.edu/resource/planting-tree-or-shrub

Next, how is the tree watered?  New trees and shrubs need monitoring and water when needed for roughly the first two years of establishment. We had a few days of unusually hot weather recently, and even just that could have been a stressor if the root area was dry.  Take a look at the following page on how to water new trees, including the important information on how to really check that the water is going where you think it is, by using a screwdriver and your finger, hopefully finding the root area cool and moist:
https://extension.umd.edu/resource/watering-trees-and-shrubs

As far as the greenish leaves, this can happen when the weather is hot.
Check to be sure that the mulch is not deeper than about 3 inches and that it is pulled back from being in contact with the trunk of the tree.

Generally trees that are less than 6' tall don't need to be tied and staked. It shouldn't be tied too tightly either. Keep an eye on it and remove or loosen it if needed. Definitely remove it within a year or so so that the thickening trunk has room to grow unimpeded.


Christine

 

Hello Cheryl,

It's hard to guess where the soil moisture is originating...it could be a leaky irrigation pipe somewhere nearby/uphill in the yard (is there an uphill neighbor with irrigation?), a natural seep below the surface, a roof downspout outlet emptying nearby, or simply a high water table that retains water for long periods after rain. Your description of the slow drainage sounds like it would definitely stress a tree like redbud (perhaps less so a species adapted to wet habitats).

Root dieback from over-saturated soil occurs because the roots essentially cannot "breathe" (they respire and need access to oxygen). In well-drained soils, the normal pore spaces (the gaps between soil particles) provide enough oxygen for root health, but overly-wet or poorly-drained soils (such as from compaction, topography, or the natural soil type) have less oxygen and more water filling those pore spaces. Roots become stressed and vulnerable to infection by opportunistic fungi, or they die outright. This triggers wilting and leaf shed since the remaining roots cannot support the entire canopy as-is, though how quickly the symptoms progress from the onset of root loss can vary. Thus, it's hard to pinpoint when the roots have reached a point of no return, at least not without digging the tree up and exposing roots by removing some of the soil.

If rot is occurring, no fungicide will reverse the damage, and these fungi are ubiquitous in the environment and not it's practical, economical, or even achievable long-term to try to eradicate them from the soil. Fortunately, plants are not succumbing to them all the time because they have their preferred soil conditions or are otherwise not stressed. If this location won't dry out (especially if you can't find the moisture source and the sogginess persists), another spot would better suit the redbud. Or, if the tree succumbs, you can try a different tree species in this spot instead.

The greening of the purple foliage is largely unrelated to root issues and is a normal feature of many purple-leaved trees and shrubs when summer's temperatures rise. Sunny exposures help to preserve the color (a pigment that acts a bit like a "sunscreen" for the foliage) while part shade keeps the plant cooler, which also slows the greening response to heat; these two factors are somewhat in conflict, so there's not a perfect solution to siting a purple-leaved redbud to keep it from turning greener each summer. Still, 'Forest Pansy' is an old cultivar among the handful on the market with purple foliage, and some of those newer forms claim improved color retention into summer.

For future plantings, we suggest not amending to soil to such an extent, as it can interfere with moisture percolation down through the soil. (There are different pore space sizes between different soil types, and while mixing them thoroughly does help even this out, the roots do eventually need to "get used to" the native soil as they grow out of the original planting hole. A good compromise is to instead top-dress a planting bed with a light layer of compost that soil life will gently incorporate for you over time.) Using just enough amendment to give a dense clay soil a crumblier texture should be sufficient, though some Extension specialists recommend not amending the soil at all to eliminate the risk of drainage changes. (That requires more planting prep work -- bare-rooting the entire root ball -- so isn't often done.)

Planting high could result in a stressful change in soil depth for the roots, so going forward, try planting so that the root flare (mentioned in the Planting a Tree or Shrub page linked previously) sits just at the soil surface. Sometimes this means soil from the surface of the root ball will need gentle removal prior to planting so you can determine exactly how deep the root ball really is. Planting high used to be recommended when the practice of digging a planting hole deeper than the root ball was advised, so as that loosened soil settled again the root ball wouldn't sink too deep; this has since been revised to digging the hole only as deep as the root ball, so no settling is involved to compensate for.

The loss of new growth you mention is not encouraging, but at this point, all you can do is to either wait and see if the tree recuperates (producing a second flush of new growth as roots regrow) or take a chance and move it to a location with better drainage. Or, wait to see if this area drains and dries further since no new water is intentionally being added. The fact that the golden creeping Jenny groundcover in the earlier photos looks in great condition may hint at the soil moisture, since this perennial thrives in soggy conditions. (It's a lovely color contrast, but the species is invasive in our area. If it creeps into lawn, it may be challenging to remove, and don't let pieces of stem enter any nearby streams/wetlands if your property abuts any.)

If you do end-up needing to replace the redbud, try to use a younger tree, because a ten-foot burlapped tree is relatively large and an older tree takes longer to establish than a younger counterpart. Since they settle-in more easily, they tend to catch-up in growth with an older tree in a relatively short amount of time. Plus, the size of the planting hole is much smaller when installing a younger tree in a smaller root ball or container.

Looking at the recent photo, the situation might not be hopeless yet, but it's a wait-and-see situation at this point.

Miri

It is difficult to say, but some soils can form what is called hard pan, or even clay soils that are compacted can act similarly, that is, form a hard layer that makes the hole similar to a pot that holds water. 
You might dig a few more shallow holes nearby and see if there is standing water. It's normal to have some water remain after a heavy rain event, but it should slowly drain away within a day or so. If not,you would probably want to remedy the situation, particularly since the area is somewhat close to your house/foundation. It may be that you need a contractor to put in a drain or re-grade the area in some way so that water does not flow or lay against the house.

As far as other plants, there are flowers, trees and shrubs that happily grow in moist or wet (though not constantly inundated) areas, and there are things like rain gardens that take advantage of issues like this. 
Happily you are located in Montgomery County, which has an environmental program called Rainscapes, which offers information, guidance and even perhaps rebates for installation of gardens that help with slowing water down, decreasing erosion and the pollution of stormwater run-off. 
You can learn more here: 
https://www.montgomerycountymd.gov/water/rainscapes/index.html
Redbuds like a moist soil, but as Miri said above, the roots still need oxygen to breath. The Rainscape folks have good plant lists that should be helpful. Many trees that can take wet conditions, like Red Maples grow much larger than you would want that close to your home. There are shrubs and flowers though that may be an option, and again, a rain garden takes advantage of a bowl shape with wetter than normal conditions and is usually planted with a variety of plants. The Rainscape people have good lists and plans to consider, as well as contractors that may be helpful if needed.
Lastly, you could try taking a long-pronged pitchfork and driving it repeatedly into the soil, widely around your redbud, and see if it helps break through the bowl to allow some drainage. It may not be enough, but it's worth trying.


Christine

Try to avoid the tree's roots, yes, though they may not be much further away from the trunk than they were upon planting, and the further from the trunk they grow, the more slender they will be.

Compaction can occur in tilled soils, yes, because tilling disrupts the natural soil aggregation created by microbes "gluing" the soil particles into larger crumbles, which aids in drainage and oxygen permeability. We used to think of tilling as a good garden practice because it visibly breaks-up chunks of soil and creates a good "crumb," but we've since learned it's detrimental to soil health. Soil structure can re-form over time, so isolated tilling events doesn't permanently ruin a patch of soil, but it's recommended that amendments are used sparingly and that the only soil disturbance occur when a plant is installed (as this is of course unavoidable). As you noted, home construction can indeed do significant damage to soil structure and causes compaction, though that too is relatively unavoidable.

Layering-on amendments over the long term, like an annual "mulching" with about an inch of compost for example, is a good way to continue improving soil texture without doing any actual digging. Loosening soil with a garden fork (insert vertically, rock back and forth without digging-up soil, and pull it up and repeat in another spot) is one way to help gently break-up hardpan soils with minimal soil disturbance.

For more thorough information, if you're curious, you can explore our various soil pages:

• Soil Basics
• Soil Health, Drainage, and Improving Soil
• Organic Matter and Soil Amendments
• Common Soil Problems

Miri