Gardens vs Tree Roots

Durable block wall raised beds with...  Under Armor !?!?

These garden beds, installed this summer, were going in near an existing Hackberry tree.  Although near the current drip line, the footprint was small, and the installation shouldn't damage its roots any more than the other construction traffic.  

However, future growth would mean that the root system would be expanding.  I was concerned about these tree roots invading the raised beds and stealing water and nutrients from the plants growing there.  

Original SPROUT Garden

At the old Sprout Garden location, nearby Oak trees had nearly filled the existing raised beds with roots.  The tending gardeners said yields had gone down over the years, but guessed it was due to diminishing soil quality and fertility over the years.  

When we reclaimed the wood to use in the new project, we found that the remaining soil was almost a solid "loaf" of tree roots!

I've have also dealt with them in my own garden as well.  Maple trees love to send out exploring feeder roots!

To address this potential problem, we wanted to create an air gap to encourage air pruning of the tree roots instead of letting them invade the growing bed. 

The gap would be filled with river rock to maintain larger airspaces to discourage invading roots yet support the growing mix above.  Starting at the bottom -

1. We added heavy fabric to keep the rock separated from the existing soil.
2. Then we added a 2-4" layer of river rock, to keep air pockets open.
3. Before filling the beds with soil, another layer of fabric was added.

If the growing mix was allowed to settle into the rock it would eliminate the desired airspace.

The vegetable beds are situated just outside the house's shadow most of the year, and being elevated helps to get more sun on them too.  

Trellises were added for some vertical growing space.

More to updates to come on this project!