Hi, Ohio tree lover, your question is an interesting one.  Nyssa sylvatica is generally not tolerant of high pH soil.  The general authority on trees and shrubs is Dr. Dirr's Manual of Woody Landscape Plants.  He lists  Nyssa growing pH 5.5 to 6.5.  I know that they will grow in a higher pH soil as I have one in our front yard.  We have higher pH soils in Fayette County.  I have tested several areas and it runs from 7 to 7.5.  The leaves in the higher pH areas will turn a yellow due to the lack of iron availability to the tree.  
 You can sometimes change the pH of the soil that you are going to plant the tree into by amending the soil with a lot of organic material.  The best one for getting the pH down is the pine bark soil conditioner.  We have used this a lot of times as it is made up of small flakes of pine bark that decompose very slowly and give an acid reaction.  It won't lower the pH very much but it might help some.

 The other thing you can do is to check out several spots where you might want to plant the tree.  You might find that native soil that hasn't been disturbed has a lower pH.  The digging of basements usually means that the soil that they dug up has been spread onto the original soil.  If you are from an area of higher pH, then that subsoil or what is closer to the "parent material" will be a higher pH and will make the soil test a high pH.  If you can find a spot that has not been altered it might just be slightly higher and be OK for the tree.  
 
 Dr. Dirr also states that proper fertilization and watering will increase the growth rate of Nyssa.  Again, we can't use too much well water here as the pH of the water is about 8 since it is from limestone aquifer.  You can use an acidifying fertilizer to lower the pH a little.  
 
 As for the ground cover, it depends on how high you limb up the tree.  If it has limbs close to the ground, then the shade will be too dense.  If you limb the tree up about seven feet or more over time, then you should be able to grow a ground cover.  
 
 To sum up, check out your pH carefully.  Try to find a place in the yard that hasn't been disturbed with fill dirt or subsoil piled on top and then smoothed out.  Native soil should be somewhat lower in pH and be OK for the tree.  Buy a container grown tree if you can since Nyssa has a strong tap root and is difficult to transplant unless grown in a container or root pruned in the nursery at a young age.  The best specimen I ever saw was when I was driving around in the Hocking Hills and there was one at the top of a hill near a fire tower.  It was ablaze in color almost like a lighted match.  I still remember that tree from over 25 years ago! 
 
 If I knew your location in Ohio, it would be easier to guess how high the pH might run.  I live on the glaciated side of Ohio and the eastern side has a naturally lower pH.  Take a chance if you want with a small tree and let it get aclimated to your location.  There is a great specimen of a Nyssa at Spring Grove Cemetery in Cincinnati.  They are spectacular in the fall.  Don 

Thank you so much for your lengthy response.  I assume from your answer that the Fire Master is no different or no more tolerant of alkaline soil than the Nyssa sylvatica in general.  I need to test my soil to be sure, but I know from elsewhere in my yard that the pH is as high as 8.  I was hoping to replace a huge River Birch that I had to take down this fall with the Fire Master, but the River Birch was dying after 40 years of nursing it due to the high pH levels.  So, I wouldn't want to chance the Fire Master if it is likely to suffer the same, slow decline. That was a hard lesson to learn.   I was so hoping the Fire Master could fill the hole in the landscape that the River Birch has left.  It was the focal point of the yard.  Thanks  again for taking the time to be so helpful.

Hi again, I've looked on line and the Garden Debut nursery seems to be the one that patented the tree.  I would guess that the pH of 4 - 8 was put on there by chance and that the nursery didn't actually test the tree to see if it would tolerate and grow at the higher pH. I think they are located in Oklahoma. 

Let me tell you another incident in my search of trees.  Everyone in our county loves the shape and color of the pin oak.  It has been planted in many yards over the years only to watch it slowly turn yellow over time and then finally die.  I purchased one and then used the Acecap Iron capsules in the trunk.  I did this several years and the tree did OK.  It was about 10 inches in diameter at one point and then the new owners didn't treat it so it declined and died.  I searched a lot of wood lots and found one growing that was over 24inches in diameter.  The strange thing was that it was about a tenth of a mile from a stone quarry that had been digging out limestone for gravel and crushed lime for many years.  How that tree tolerated the higher pH soil in that area I don't know.  Sometimes a pocket of soil that is different exists where you don't realize.  The other possibility is that the mycorrhizae that inhabit the soil and then the fine hair roots of the tree made the difference for the tree.  Some nursrymen believe that the fungi that inhabit the roots makes all the difference to the growth of the trees and will try to keep the high organic matter in the soil so that it will colonize the young trees.  They have tried to conduct experiments showing the difference but it is difficult to keep the mycorrhizae out of the experiment since the spores are everwhere.  Anyway, some swear by the addition of the fungi and others say there is no difference.  Some greenhouses now purchase potting soil for their spring plantings that contain the mycorrhizae added when they bag the medium.  They show larger transplants over the regular potting soil. 
 
 So if you want to experiment, take the chance.  You might be able to pull it off with a lot of organic material in the soil and pine bark mulch.  Good luck in your quest. Don