Planting Bed in Greehouse floor.

Hello all,

We would like to make an inground planting bed in the GH floor.


What I've thought was to make it about 2 1/2 ft wide x approx 18" deep. I would stretch from end-to-end against the South Wall and butt against the walkway..
I will only be able to raise it 3 1/2 " above floor level but that would be ok.

Need advice please if my depth & width are ok ?..........

What to use for a divider to keep the earth off the walk ?......(that won't rot but look nice too)..

There will be about 12" of fairly good soil there to start, so I still need to add about 6" of fill. What should be added to make a really,good, rich, Planting bed ?

Greenhouse is not up yet & I'd like to get this in before it's here. If the Spring Thaw comes...

I know you 'll steer me right.

Thankyou, Paul

I don't know how that would work out for you, Key West. The floor of your green house in the winter is probably only going to be 5-10 degrees above the outside ground temp down through the first 6 ". Any deeper, it's going to match the soil temperature around it (as in COLD!). If the roots of your plants are too cold, they just won't grow well for you. Ran into this fact in a small cold frame I built many years ago. I solved it by sinking an electric heating cable 1 foot under the surface which did the trick, but I think it would be a major expense on a large area. Your other option would be insulation between the frozen tundra and your growing bed. That also sounds pretty expensive. You might be better off sticking to pots sitting on insulboard...

StonoRiver,

South Carolina, boy that's God's Country!! Lucky Boy.

I did not mention that I plan to add 2" Insulation Board beneath the whole floor @ 18" deep.
Insulation board will also be added all around the outside as well. so, the whole thing will be wraped in a 2" wall of foam.
I was in hopes that this may help retain warmth.

Maybe your right, maybe still too cold...?
What if I brought up the level of the Insulation board to about 12"? Maybe that would help?

A soil cable, now that's an idea too... Wonder on the running cost all winter?

I wish I could come up w/ a warming process that would be economical to use...

Thanks for the input.

Paul

Keywest, I wouldn't bother with the 18" deep foamboard. You just risk drainage problems.

Just do the perimeter. As we discussed elsewhere, studies of heat loss show only 2-3% through the perimeter of the floor, with the vast majority going through the roof. I have 18" deep beds in my GH and the plants grow like weeds in there. Here is a pic. The ground level bed is in the foreground. It is raised about 6"

Stressbaby,

What a beautiful job your hands have done!

Thanks, paul

I used PT lumber and I lined the frames with 6 mil plastic to keep the wood dryer and keep any chemicals out of the soil. I used good topsoil, well amended with peat and rotten manure.

I think your diminsions are fine.

It's all trade-offs, Key West! You got frost to deal with, I got heat and humidity. One thing I've thought about is that if the frostline is say,18" below surface, what if I excavated down 24" (below the frost line), built a knee wall 3' high , and set the greenhouse on top of that? And if I heated the subteranean floor with solar heated water like they do with these high-end house flooring systems, why wouldn't the earth under the greenhouse act as a huge heat sink that would reduce demand for additional (hydrocarbon generated) heat? That's as far as I got with my theorizing before escaping to the south---now I'm "reverse engineering" the process!

hey keywest check this out It's Tekfoil which is sorta expensive but it will warm the floor!

http://www.farmtek.com/farm/supplies/cat1a;ft1_tekfoil_reflective_foil_insulation.html

Kyleg05,

Thanks for that information...
I have a whole roll of that in the barn.

You have me pondering again,
Paul