Building raised beds

ScottinAtlanta · October 14, 2011

Folks, There is alot of great information on raised beds on the posts in this Forum, and thank you again for your time and energy in creating this repository of wisdom.

I am putting 6 raised beds in November for planting next March. They will be 3 feet by 25 feet by 12 inches.

One question that I cannot find an answer to is this: why do people generally cover the bottom of the beds before building up the soil? Some on this forum use cardboard, others use newspaper or other materials.

I am building the beds on what was formerly a lawn - I used it this year for gardening but the quality and hardness of the soil reduced my yield. Do I need to cover the bottoms of the beds before I build my soil in the raised beds?

A second question is this: When you have a raised bed, are there special watering techniques that you use? Does it dry out faster? I plan to have a trench running down the center and just use it as an irrigation channel (they run downhill at a slight slope). Is that a good idea?

Thanks again.

Keiththibodeaux · October 14, 2011

Covering the bottom is usually done for weed suppression in my area.

Tom C zone 4/5 · October 15, 2011

Generally I've used a light barrier of cardboard to reduce infiltration by grass-weeds, on new beds.

Soil in lawns tends to be compacted. Creating a 'no-walk' space by use of a raised bed (and the liberal application of organic material) enables soil all by itself to start to decompact. Worms also start the heavy lifting of airating soil.

On subsequent years I do start double digging, to get OM (organic material) mixed into subsoil.

Your Georgian climate should permit use of cover crops to be turned under too.

bobberman · December 8, 2011

I would use leaves on the bottom several inches. Cardboard takes to long to decompose and a few layers of paper are better. I would put some type of fertilizer top the grass which will help kill it and make better deep soil! Sand is also good as a 2 inch layer! There are alot of options. Don't forget that a raised bed like you are making works great as early cold frame which can be changed over to the raised bed later in the spring! The grass will make great deep rich soil! Watering would be easy since it will hold the moisture as well as any garden! If you have paper shredder that works great also!

MikeInOhio · December 11, 2011

Scott,

I have been growing in raised beds for many years. I do not agree with the idea of placing a "weed barrier" under the bed. I till the soil at least 8" deep under the raised bed before I assemble it. The weed barrier also acts as a root barrier.

I place a drainage tile (usually 2" pvc with holes drilled in it, surrounded by pea gravel) about 6" deep in the existing soil for drainage. It works great here in Ohio.

You will need to water a bit more than an in-ground garden. Your drainage is far superior so you don't need to worry much about over-watering.

bobberman · December 12, 2011

A weed barrier is bad for roots unless it is one like paper that decomposes quick and the roots can push their way through easilt one it gets wet!

ScottinAtlanta · December 13, 2011

Thanks, folks. I did not use a weed barrier at all in the end - I wanted the worms to rise easily into the new beds. Thanks for everyone's comments, which I have found enormously useful.

TexasSue · January 11, 2012

I would rough up the bottom grass soil good ,add leaves,chopped newspapers and household compost,bagged compost , manure ,lots of fish guts and bones if you can get it and anything I could compost as 12" deep takes a lot of soil ,layer all this stuff add some fertilizer and layer more composting stuff mentioned and then cover with a nice soil ,water and let it set till spring or for march planting, you are in Georgia and it wont be decayed so use gloves to plant . Heat makes stuff decay quickly . When I had a raised bed like yours,I measured and made a curved bed using cement blocks and then ran a soaker hose with a timer on it down the middle and planted on each of the sides and where the hose ended,I stopped my raised bed . This worked great for me and the holes in the cement blocks worked good for some herbs and flowers ,then I moved

Worth1 · January 21, 2012

I would put the raised beds in level not at a slope, one for looks and the other is so the water drains evenly or the up hill side will dry out faster.

But all of this is relative to how much of a slope you are talking about.

If it is too much of a slope if you are going to add poles or other things to the beds for cover and such it can turn into a nightmare.

You will be asking yourself should I make them level or square.

For me level AND square is best.

Worth

October 14, 2011	#1
ScottinAtlanta Tomatovillian™ Join Date: Jul 2011 Location: Atlanta, Georgia Posts: 2,593	Building raised beds Folks, There is alot of great information on raised beds on the posts in this Forum, and thank you again for your time and energy in creating this repository of wisdom. I am putting 6 raised beds in November for planting next March. They will be 3 feet by 25 feet by 12 inches. One question that I cannot find an answer to is this: why do people generally cover the bottom of the beds before building up the soil? Some on this forum use cardboard, others use newspaper or other materials. I am building the beds on what was formerly a lawn - I used it this year for gardening but the quality and hardness of the soil reduced my yield. Do I need to cover the bottoms of the beds before I build my soil in the raised beds? A second question is this: When you have a raised bed, are there special watering techniques that you use? Does it dry out faster? I plan to have a trench running down the center and just use it as an irrigation channel (they run downhill at a slight slope). Is that a good idea? Thanks again.

October 15, 2011	#3
Tom C zone 4/5 Tomatovillian™ Join Date: Jan 2007 Location: SE Ohio Posts: 253	Generally I've used a light barrier of cardboard to reduce infiltration by grass-weeds, on new beds. Soil in lawns tends to be compacted. Creating a 'no-walk' space by use of a raised bed (and the liberal application of organic material) enables soil all by itself to start to decompact. Worms also start the heavy lifting of airating soil. On subsequent years I do start double digging, to get OM (organic material) mixed into subsoil. Your Georgian climate should permit use of cover crops to be turned under too. __________________ Beyond the mountains, there are more mountains.

December 12, 2011	#6
bobberman Tomatovillian™ Join Date: Dec 2011 Location: Latrobe Pa. Posts: 142	A weed barrier is bad for roots unless it is one like paper that decomposes quick and the roots can push their way through easilt one it gets wet! __________________ Frank the Bobberman & Carpet Installer Inventor of the Bobber With A Brain,. Gadening, Greenhouse, Fishing, Softball, Scrabble. Single looking for a woman with a 100 acre farm!

October 14, 2011	#2
Keiththibodeaux Tomatovillian™ Join Date: Jun 2011 Location: Louisiana Posts: 587	Covering the bottom is usually done for weed suppression in my area.

December 8, 2011	#4
bobberman Tomatovillian™ Join Date: Dec 2011 Location: Latrobe Pa. Posts: 142	I would use leaves on the bottom several inches. Cardboard takes to long to decompose and a few layers of paper are better. I would put some type of fertilizer top the grass which will help kill it and make better deep soil! Sand is also good as a 2 inch layer! There are alot of options. Don't forget that a raised bed like you are making works great as early cold frame which can be changed over to the raised bed later in the spring! The grass will make great deep rich soil! Watering would be easy since it will hold the moisture as well as any garden! If you have paper shredder that works great also!

December 11, 2011	#5
MikeInOhio Tomatovillian™ Join Date: Dec 2011 Location: Ohio Posts: 132	Scott, I have been growing in raised beds for many years. I do not agree with the idea of placing a "weed barrier" under the bed. I till the soil at least 8" deep under the raised bed before I assemble it. The weed barrier also acts as a root barrier. I place a drainage tile (usually 2" pvc with holes drilled in it, surrounded by pea gravel) about 6" deep in the existing soil for drainage. It works great here in Ohio. You will need to water a bit more than an in-ground garden. Your drainage is far superior so you don't need to worry much about over-watering.

December 13, 2011	#7
ScottinAtlanta Tomatovillian™ Join Date: Jul 2011 Location: Atlanta, Georgia Posts: 2,593	Thanks, folks. I did not use a weed barrier at all in the end - I wanted the worms to rise easily into the new beds. Thanks for everyone's comments, which I have found enormously useful.

January 11, 2012	#8
TexasSue Tomatovillian™ Join Date: Sep 2011 Location: Texas Z8 Posts: 24	I would rough up the bottom grass soil good ,add leaves,chopped newspapers and household compost,bagged compost , manure ,lots of fish guts and bones if you can get it and anything I could compost as 12" deep takes a lot of soil ,layer all this stuff add some fertilizer and layer more composting stuff mentioned and then cover with a nice soil ,water and let it set till spring or for march planting, you are in Georgia and it wont be decayed so use gloves to plant . Heat makes stuff decay quickly . When I had a raised bed like yours,I measured and made a curved bed using cement blocks and then ran a soaker hose with a timer on it down the middle and planted on each of the sides and where the hose ended,I stopped my raised bed . This worked great for me and the holes in the cement blocks worked good for some herbs and flowers ,then I moved

January 21, 2012	#9
Worth1 Tomatovillian™ Join Date: Feb 2006 Location: Den of Drunken Fools Posts: 38,539	I would put the raised beds in level not at a slope, one for looks and the other is so the water drains evenly or the up hill side will dry out faster. But all of this is relative to how much of a slope you are talking about. If it is too much of a slope if you are going to add poles or other things to the beds for cover and such it can turn into a nightmare. You will be asking yourself should I make them level or square. For me level AND square is best. Worth