What's in the bottom of your raised bed?

What is on the bottom of your raised bed? I have heard of leaving it open to the bare ground, placing a layer of cardboard or landscape fabric to block weed/grass, double digging under the bed and even solid bottoms. Reason I'm asking is I am planning to move mine to a spot that gets more direct sunlight when my cold season crops come out and am curious what everyone else does.

Here in Ohio in ten beds I used cardboard to kill off weeds and hardware cloth to let in the worms and keep moles and voles out.

Double layer of cardboard.  It's probably mostly all disintegrated by now.
CC

I have elevated beds (tabletops), but when I had them on the ground, I just used weed cloth. After 3 years of neglect and not using them, they were eat up with small roots.

For my 8-4 x 4 beds I used all the cardboard I'd saved through the winter. Had to or my family would have had a hoarders intervention!  I have an area I double dug last year and plan on putting 3-4 x 8 beds on that area.  I'm leaning towards leaving them open.  They are going to be planted in the 3 sisters anyway so I'm banking on the zucchini acting as living mulch.  Anything that pokes it's weedy head above that and isn't a cornstalk or bean bush/vine gets summarily yanked, unceremoniously shredderated, and COMPOSTED most post haste. If not post hastier.

My raised beds are 900 mm ( 36 inches dep the walls are made of mortared enginering brick .
 
 The beds are built upon 300 mm ( a foot ) thick concrete footings , each bed has a 500 x 500 mm  ( 18 x 18 ") square hole in the middle of each beds foundation .

 The first foot of each of the beds was filled with washed clean sharp sand . Then two feet of un composted stable muck ( bad idea  horse stomachs do not kill weed seeds ) .
  When the stable much had dropped down to about 12 " dep  after giving it a darn good watering every day for a week I  filled the beds up with "  Mel's Mix " made with my own dung & wheat straw based composted materials.

As it settled down I added more of my Mel's Mix  it took about six cubic yards of MM in the end to fill about 220 sq feet of my raised beds .

 Now seven years later my compost these days is a lot lighter on the home composted dung & straw beddings  as I got four cubic metres of Leylandi fir trees to put through my shredder . That was composted separately in strong black zip tied rubble sacks that were kept under cover out of the rain for a couple of years then I've been mixing it with large 310 litre lidded  composting bins of domestic kitchen waste & all food scraps  waste , shredded  paper or cardboard  , dead , dying or surplus plants & lawn cuttings then letting it compost with out any more turning over for a good six months having first added a hand full of brandling worms to let them work their way into the composting material thus producing plenty of worm casts in the final compost.

 This has eventually become a reasonable fiberous compost that appears to be very good for my beds as seem to produce some great crops .

Cardboard if the ground previously had weeds or invasive grass.  Nothing if the ground under the beds is fairly weed free and nothing invasive.

Nothing.  I built beds in the old wide bed garden so there was no need. I battle with quack grass sneaking in but usually a year of black plastic over the bed and its neighbor paths will end that.

mlpii66 wrote:For my 8-4 x 4 beds I used all the cardboard I'd saved through the winter. Had to or my family would have had a hoarders intervention!  I have an area I double dug last year and plan on putting 3-4 x 8 beds on that area.  I'm leaning towards leaving them open.  They are going to be planted in the 3 sisters anyway so I'm banking on the zucchini acting as living mulch.  Anything that pokes it's weedy head above that and isn't a cornstalk or bean bush/vine gets summarily yanked, unceremoniously shredderated, and COMPOSTED most post haste. If not post hastier.

 Take care to identify what are know as perennial pernicious weeds , unless you are spot on with a high quality composting methods . Like as not you will still find that the perennial weed will have survived either as seeds or tiny bits of weed that decide to grow once you spread them in compost into your beds .
 The only two ways I know of destroying such prennial weds is to dry thm out & burn them .
or
Submerge them in a thick walled strong light proof lidded  trash can 3/4 filled with plain water .  Put all the weeds in , in one go don't add any more till the batch is stewed . Put the lid on & stir them every day for 14 days . It will stink to high heaven , usually be an oily black colour & make you feel like throwing up ( aim for the bin if you do as it will also be a useful additive to th decaying matter) .
 When all soft green matter has fallen off the weeds /roots  you can safely pour the elixir into a compost bin on top of composting materials and also put any bare skeletons of the former plants in to the compost bin as well .

plantoid wrote:My raised beds are 900 mm ( 36 inches dep the walls are made of mortared enginering brick .
 
 The beds are built upon 300 mm ( a foot ) thick concrete footings , each bed has a 500 x 500 mm  ( 18 x 18 ") square hole in the middle of each beds foundation .
 

As the locals here in Idaho say with a chuckle, "Godfrey!"

I am jealous!  How many beds did you build that way and how long did it take?  I would like to build a greenhouse and beds like that would be right at home in the hot house.

Nothing at all in my main old re-purposed window boxes...they originally had wooden bottoms, but those were broken or disintegrating by the time I put them to their second purpose!  Probably gone....

In my 1 year old 4x4, cardboard.  I would do cardboard again.  I see the worms and such in there!  It seems healthy.

When I first saw the question, I was going to answer Mel's Mix.   The first year, when the beds were on the ground I lined them with weed fabric.  The second year I realized neighboring roots were invading through the weed fabric (It's weed fabric, not root fabric ) so everything came off the ground with air space underneath.  So, the answer is plywood with drainage holes, lined with commercial weed fabric to keep in the Mel's Mix.

plantoid wrote:

mlpii66 wrote:For my 8-4 x 4 beds I used all the cardboard I'd saved through the winter. Had to or my family would have had a hoarders intervention!  I have an area I double dug last year and plan on putting 3-4 x 8 beds on that area.  I'm leaning towards leaving them open.  They are going to be planted in the 3 sisters anyway so I'm banking on the zucchini acting as living mulch.  Anything that pokes it's weedy head above that and isn't a cornstalk or bean bush/vine gets summarily yanked, unceremoniously shredderated, and COMPOSTED most post haste. If not post hastier.

 Take care to identify what are know as perennial pernicious weeds , unless you are spot on with a high quality composting methods . Like as not you will still find that the perennial weed will have survived either as seeds or tiny bits of weed that decide to grow once you spread them in compost into your beds .
 The only two ways I know of destroying such prennial weds is to dry thm out & burn them .
or
Submerge them in a thick walled strong light proof lidded  trash can 3/4 filled with plain water .  Put all the weeds in , in one go don't add any more till the batch is stewed . Put the lid on & stir them every day for 14 days . It will stink to high heaven , usually be an oily black colour & make you feel like throwing up ( aim for the bin if you do as it will also be a useful additive to th decaying matter) .
 When all soft green matter has fallen off the weeds /roots  you can safely pour the elixir into a compost bin on top of composting materials and also put any bare skeletons of the former plants in to the compost bin as well .

Thanks for the tips! Been a long while since I've composted and my piles I put up before winter never heated.  I did it from long ago memory and dorked up the layers.  I put dirt between the greens and the drys instead of dry/green/dirt layering.  I also had to shut off and purge the outside lines as the cold was coming early so I think there wasn't enough moisture either.. Nothing sprouting out of the top... YET!

Burning is definitely in the cards for the tumbleweeds!

The soaking method is new to me but reminded me of something I used to do similar.  I'd put grass clippings and weeds in a contractor style trash bag, a spade full of dirt, a bit or water and tie that critter up tight, roll it around a bit and leave it in the sun for a week or two.  It would swell like a weather balloon. When it went back down I would open it and it looked and smelled like a huge cow patty!  Don't remember having trouble with weeds reseeding from that stuff. Read about it in an old Mother Earth News or Organic Gardening and Farming magazine from the '70s, back when they were useful and not catalogues for hipsters buying their way back to the land.

I built new beds this year and used hardware cloth attached to the bottom to keep the moles out, then lined them with weed cloth.  The beds I replaced I just used weed cloth and after 3 years it was pretty much disintegrated, but I didn't have any weeds come up so it must have done the job.

I don't have burrowing pests like moles, voles or gophers so I just put down a double layer of cardboard and it seems to have been an earthworm magnet. Tree roots might be a concern anywhere I put it in my yard. No trees in the middle but down the sides by the fence there are a few except in the back I have an alley as a small buffer area. The back gets the most sun so that's where I'm planning on moving it. Contemplating breaking the soil up under the bed or double digging as best I can as there is limestone about a foot down. Give the deeper rooted plants a place to go beside straight into hard black clay soil.

This might be sacrilege...but at the bottom of ours is nothing more than the earth on top of which the beds were placed.

Cant say we've ever had a weed issue beyond that which blows in. Granted the walkway around the beds is gravel-over-fabric.

Sunsanvil wrote:This might be sacrilege...but at the bottom of ours is nothing more than the earth on top of which the beds were placed.

Cant say we've ever had a weed issue beyond that which blows in. Granted the walkway around the beds is gravel-over-fabric.

My original "boxes" were naked.  It isn't sacrilege.  I like them!

Mostly invasive tree roots.

NSR

I am just getting ready to set up my first sfg. I was thinking to put a layer of cardboard and weed fabric down. My question is, do I need to remove all the grass first or will the cardboard kill the grass?

Cindy G wrote:I am just getting ready to set up my first sfg. I was thinking to put a layer of cardboard and weed fabric down. My question is, do I need to remove all the grass first or will the cardboard kill the grass?

Cindy ... I added two new 4x4 boxes/beds last year over grass.  Here is what I did. First I used my weed wacker to take the grass down to the level of the soil. I did NOT remove the grass roots.  Then I put down a layer of cardboard. The boxes also have weed fabric on top of the cardboard. I have had no problem with grass in those beds.

My boxes are raised off the ground because they sit in the swale; so plywood bottoms with drain holes is the bottom.

Thank you for the advise and the pictures. Can't wait to get started!

When I moved my beds I used two layers of cardboard under the bed over my lawn grass, then I covered my walkways also with two layers of cardboard then used woodchips down over the cardboard over my lawn grass, on the edges I only have a single layer and the only thing to come thru that is nut grass. The big reason I don't dig in my back yard is I have a large metal electrical box in the corner of my yard it could be a shocking experience, I know the wires are supposed to be buried deep But.  

I'm planing to use 2 layers of concrete block to make my raised bed. I have everything I need for my MM in the top 8" layer, but what should go in the bottom 8" as filler? I have heard/seen suggestions of recycling items - glass and plastic. Is that actually a good suggestion? What about sand? I like the cardboard and clippings suggestions posted in this thread but I don't have almost a yard worth of that stuff.