Having read the "dead grass" thread, I'm afraid I'm in for bad news.
Writing from SE Michigan, zone 6. The front lawn has a maple tree -
red maple, I think - at least in the fall the leaves turn red. It
casts a deep shade, but worse is that the ground around it has lots of
thin roots. Needless to say, no grass grows there. I was thinking of
using a slit seeder, thinking that would cut the roots. But, well --
is there any type of grass that will grow there?
I'm in the same zone as you, probably 100 or 150 miles to your east.
Put down a layer of good black soil under the tree. Not the shit they
call compost or peat moss. 1 or 2 inches is all you need. Mix in some
24-24-24 lawn-starter fertilizer.
If you want instant grass - buy some sod and lay it down. If you seed,
you want a deep-shade grass seed (Supranova Poa Supina / Supranova
Soil and roots WILL NOT BE your problem (unless you have clay soil). It
will be the shade. What is the diameter of the tree trunk? Can you
walk under the tree when it's fully leafed-out in the summer without
hitting your head on leaves or branches?
Bingo. Exactly the problem I described in the other post. Some
species of trees, some maples in particular, have these thin, dense
roots that stay close to the surface. The Norway maple is well know
for this problem and is a big planting mistake for areas where you
want to grow grass. The roots are dense enough that a slit seeder
will not cut them, only bounce around and run over the top of them and
NOT penetrate the soil. I have a maple here in my yard and have been
through this experience. I don't know of any grass solution that will
work, because you have a dense root system at the surface that crowds
out any grass and sucks up the water and nutrients.
Go ahead and try that approach. Been there, done that. Bluegrass
may be an even worse choice because it has higher nitrogen
requirements than other grasses. So, to try to make it grow, you'll
be applying fertilizer. Guess what else wants that fertilizer and
other nutrients? Those pesky thin, dense, tree roots from your
Maple. So, they will start extending up into that nice new topsoil
too. And in a year or two, you'll be back where you started.
He's already trying to grow grass under a tree. Don't you think the
tree will already be depleting the soil anyways?
Anyone who wants a thick, healthly lawn will already be applying
fertilizer. Your argument is a red herring. His problem will a
reduction in sunlight starting in mid-june until fall. You put any
other type of grass there and it will thin out quickly.
So what's wrong with fertilizing your trees?
Unlikely. I've got several large maples (silver and sugar) and the only
surface roots I see are large and woody and would easily be burried for
years if I covered them with an inch or two of topsoil. It's the
cotton-woods and locusts that grow agressive surface roots much faster
that are more troublesome.
I don't know very much those issues about maples, but I think the roots
generally develop upwards in asfictics soils where not enough air close
to the roots prevent them to absorb mineral elements (the mineral
absorptions requires chemical energy produced only
if there is enough air close to the roots). In other case the roots go
upwards. This phenomenon is very common in plants growing in town
streets under pavements.
I think if you have enough organic rotting matter on the ground below
the tree, the soil mantain more soft and aired and only thin roots will
emerge over the soil.
Besides you can grow your lawn early before maple leafs are so wide to
prevent light reach the soil.
In my country garden there is an hedge maple and their branches ad leafs
don't prevent clover to grow.
Clover give nitrogenum to the maple and let soil water get out through
stomes, so that soil is not so wet to cause maple suffer air scarcity.
Do you think that trees have the same fertilizer requirements as turfgrass?
And you'd shorten the trees lifespan, in the process. Those roots are there, at
that depth, for a reason. That's where the water, nutrients, and more
importantly, oxygen is located. If you bury the roots deeper, you'll deprive the
tree for many years of one or more of those things. Please don't profess to know
about trees, their growth habits, and their nutrient requirements. You obviously
have little to no training in the subject.
Why not do what's best for the tree, and put a layer of organic mulch out to the
dripline? You'll protect the rootmass, which in a maple grows much more
horizontally than other trees - hence the stiff competition with the grass, as
well as conserve water and promote Mycorrhizae symbiosis.
I have seen many species of trees in urban settings that are surrounded
by paving almost up to their trunk and they grow very large and appear
Paving like that is not something I would ever do or recommend, but it's
clear evidence that the idea of adding a few additional inches of
topsoil under trees will have ZERO effect on oxygen availability to the
roots, and a healthy layer of turf grass under a tree will probably do
more for water retention and keeping the soil moist and cool in the
middle of summer vs having bare soil.