Stone & Gravel Checklist
- Stone (I'm calling the fine pea gravel around the drainage "gravel" and the heavier road stone, or river rock, or
whatever is cheaper, "stone"). We used road stone - 1" and larger limestone here in SE Iowa - you can use whatever is cheapest.
You want to end up with no stone under your planting beds, about 6" of stone under your 'simple foundation', and
about 12" of stone around the planting beds. For us, that was about 7-8 tons, delivered in 2 yard loads so we could
schlep it around with a wheelbarrow. Great exercise! We just started ordering it, and when it was used up, ordered
more until we had enough. The procedure will be something like this:
I'll come back to each of the above points shortly
- Place stone around edge as foundation for a 12" x 8" concrete "beam" that has rebar in it
- Build forms, place the rebar and pour the concrete
- Build your planting bed forms
- Start putting dirt into the planting beds
- Alternatingly, add more gravel between the planting beds - do it alternatingly, because if you don't the
planting bed edges will bow in or bow out depending on where the most pressure is
- If you have sandy soil and/or are skipping the drainage
- Put in your flashing and insulation and then immediately start putting in the road stone to hold
it in place
- Anything less than about 6" of stone will allow the flashing and insulation to blow around in a good storm. If in doubt,
add more - you can level it later.
- Foundation Start by creating a solid shelf of gravel around the perimeter, at least 6" deep and about 2-3' wide. You won't want gravel
under your planting bed, ultimately, but you do want a solid shelf that you can work on. You'll be compacting it,
mechanically or by hand, you'll build forms (and they can't be too strong), you'll place some rebar, and pour concrete. We'll go through it step by step.
Of course, a concrete foundation is probably not essential but we did one because.
- With Iowa's high winds we wanted to be dang sure that the greenhouse would be solidly anchored and not blow away.
- We wanted to make it hard for rodents, like chipmunks to get in and dig everything up inside
- We wanted to have a good solid foundation to fasten the pvc pipe/rebar ribs of the greenhouse
- Place about 6" of stone x about 2' wide around the perimeter. This is going to make a base for your
ultra simple foundation. You want to compact it. You can rent a gas compactor, or do what we did - just keep
tamping it with a heavy tamper - a rod with a ~10" square heavy piece of iron on the bottom. Get it compacted good and firm.
Drainage, Insulation, Flashing |
Stone & Gravel |
2 x 4 Walls