A narrow, shallow little creek runs along the back edge of our lot. I'd say it's maybe 5' below the yard level, and the drop-off (bank) is very steep. Think of a very small stream running through a ravine & you should get the idea.

Now, that 'ravine' effect will probably contribute a lot to drainage, and while we're Zone 6 in southwestern KY, our summers can get hot (well into the 90's at times).

If I plant a Japanese Stewartia, for example, several feet from the edge of the yard, will the tree's roots run to the edge of the yard, the 'trench' or ravine or whatever you call the open split in the earth over the water, and stop, or will the roots run steeply downhill close to the creek, which would help ensure a constant water supply?

I know tree roots tend to grow shallowly horizontally, but can they grow shallowly VERTICALLY?

Richard.

Dan

I don't know that Stewartia spp. are typically a riparian zone species, though, as opposed to the local natives you will have in southwestern KY, like Platanus occidentalis, Fraxinus pennsylvanica, Ulmus americana, Acer saccharinum, several Quercus spp., and possibly more depending on your soils.

Additionally, Stewartia spp. are not typically that vigorous a species for KY, so no matter where the roots of this plant end up, they are not going to arrive there quickly.

Tree roots (plant roots) grow where soil conditions suit them (air/gases, moisture, pH, temperature, etc.). The top of bank may be so dry that the Stewartia spp. roots won't survive there and thus may never head to the lower reaches that are moister.

You might want to consider gradually altering the bank conditions to a gentler slope, or maybe some sort of terracing. Really steep unvegetated banks along water courses generally mean severe erosion over time.

i dont quite get the vertical part of your question .... think about it this way ....

if a given tree PREFERS its roots to be 12 inches below the soil ... it will grow the roots 12 inches below the soil.. on its way to the water source ... and it will get there..

but i dont think its going toward the center of the earth [vertical] and then turn 90 degrees toward the water [horiz] ...

perhaps your idea that a tree knows the difference between vertical and horiz. is a bit of a Anthropomorphism .. see below ...

all this said .... a recent transplant requires certain care.. regardless of native water .... and you are responsible for it for a couple years.. you cant just not water it at transplant, because water is not far away ... but you probably knew that ...

great debate

ken

Dan

The limiting factor will be the condition of the soil along that bank. The roots have no problem growing down, just under the surface of the soil, but that soil must be fairly supportive of what a root system (and tree) requires.

So if the bank of your creek or flash flood drainage channel has been stabalized enough to prevent bank errosion, like is often provided with step terracing of the bank, then your bank would also need trees or building structures that would provide your Japanese Stewartia the afternoon shade it would need in your high 80s to lower 90s hottest part of summer times.

Even with those provisions the tree would still need to receive a proper water schedule, which was just enough to keep it alive, while still creating condtions that would cause the tree to grow it's roots down several inches below soil levels until till it reached just the right amount of moisure from the creek, which the banking had absorbed.