Opinions on soil for my new raised garden beds

[A-C]

i built these raised garden beds so it would be easy to tend to for my family. Now that I've built the beds, I'm wondering what to fill the bottom with? Ive read that I only need about 12-18 inches of soil to have a solid garden and I would rather not use garbage fill dirt because it will tend to get heavy and Any ideas about how/what to fill the bottom with that won't harm my plants? Would mulch be a good option?

Lastly, I was thinking about lining the side walls with plastic to keep the dirt+moisture in the bed. Any help with why this is a good/bad idea and suggestions with better ones would be greatly appreciated

 

[johnny canoe]

Great job on those beds you built! I think plastic might make the beds too wet. I use a light liner in my veg trug. They came with the trug. I'm guessing they must be a landscape fabric but very light and they have a cloth feel not a heavy plastic type landscape fabric. I bet one might find rolls of the stuff at a big garden centre or a place like Lowe's.

 

[A-C]

Awesome, thanks for the tip. Any suggestion on what to use (or not use) the first foot of the beds with? I was thinking those big Tupperware moving containers turned upside down...thoughts?

 

[johnny canoe]

I'm not sure but whatever it is must allow for good drainage.

 

[(Sub)Urban Farmer]

My concern with plastic (Tupperware) would be whether it was food grade or not. Rock would be ideal, I'd think. But, probably pricey.

Would sand be a viable option? Depends on the soil where you live. Where I'm at, we have a lot of sand pits nearby. Last time I got some in bulk I paid like $40 for a bulldozer shovel full dumped into the bed of my pickup.

I really like the setup, btw. I'd like to do something similar.

 

[Tech]

You're wanting to fill the bottom of it with something to lighten the load because you're worried about it bowing out or? I'm not sure lessening the weight at the bottom would have any less effect on it bowing. It would be non existent, it doesn't take much to retain soil. I'd be more worried about rot and having enough drainage or enough water retention, is that wood treated?

The thing that worries me is the boards, they don't look treated and I've used 1/2 inch pine in a similar build that only lasted a couple years before rot took effect. If it's not treated, painting the insides and lining with a vapor barrier might be a viable option.

 

[Doelman]

I would think you could put down 57 stone for a good base material. We use it all the time for road construction because it drains well and is cheap. I can't think of any reason it wouldn't work for gardening as well.