Raised bed question....sort of?

seymour_man · March 8, 2018

Hi All,
In my urban garden adventure I have went from couple of rubbermaid totes of heirloom tomatoes to buying a tiller and digging up a 20ft x 40ft garden space. I am on sandy soil and I have approved its structure with organic matter so its pretty decent...not great but decent.

I feel that out of my 800 square feet of heaven I waste a lot of space. I garden like it's a farm with 30 inch tiller paths around the edge and between the rows. I estimate I have less than half in plant utilization space.

Over the winter I have seriously thought about building raised beds. I think in my garden spot I can actually increase my "plant space" and after the initial investment to build the beds decrease my spending as I will not be "feeding" 800 square feet but only the actual area I use.

I plan to build 8ft x 4ft beds out of eastern red cedar. This cedar is not cheap but is very durable. I am not putting anything wire or fabric on the bottom as I want the plants to grow into my top soil as needed. I will fill the beds with organic matter and compost as needed.

Here is my question....How tall do I need to make the beds? I understand if I was making these beds as giant containers with bottoms then 1 ft or even 2 ft would be minimum.

But with my beds being open on the bottom how high do I need to go? Is 6" or 8" tall ok? As I said cedar is not cheap. I could design it to use the shorter height now and then add another 6"-8" row next year?

Any comments or advice is greatly appreciated.

SueCT · March 8, 2018

Even 4" would be fine because you are actually planting in the ground not in beds. So the depth doesn't matter, the plants are not limited by the depth at all. But not exactly sure what you will accomplish. You could just amend the soil around the plants themselves instead the entire garden and accomplish the same thing. If you want to provide a barrier, in order to contain mulch or amendments, you only need to make it as deep as you want to make the amendments. But remember they will fill up quickly. Consider how deep you have good amended soil already and how deep you want the final amended bed to be. Add a raised bed that will give you the final depth you want. Is that what you are trying to do, is use less material? The roots are still going to spread out below the sides of the raised bed in the ground.

eyegrotom · March 8, 2018

Hi I agree with Sue 2x4 or 2x6 will work. If all you want to do is basically cut down on the area that you feed or amend, Mike

seymour_man · March 8, 2018

I see your point that height would not matter. You used the term barrier and that is probably the best description.

One thing I would like to get away is the tilling. I am 67 so it is not as fun as it used to be. Having the beds would create a barrier and keep me and the grandkids from walking and packing down where I plant. Also without tilling I can have narrower paths and more planting space. Every 4 square feet is another tomato plant....lol.

Also, while my soil is decent I would like to improve it more. As you said I could just add directly without the beds. Creating that raised bed barrier would allow me to concentrate directly in the planting area. I agree that 4" would work but long term 6"-8" would be better. My big question is will that be enough or should I eventually want 10"-12".

The reason I am asking is that I plan to use 4x4 posts on each corner to attach the boards to. If 8 inches is sufficient I can cut the corn posts that length. If I want to add another board later then I can cut the post longer now and attach the board later. I know that sounds confusing.

Thanks for giving me advice I really do appreciate it.

eyegrotom · March 8, 2018

Hi Seymour you can make your raised beds as tall as you want. However with the cost of materials and the time to build them I don't think that anything over 6 inches is worth it. I have raised beds that are 12 inches tall, but mine have a wire mesh bottom. I have not had any problems with growing Toms, for the 3years that I have grown in raised beds. Mike

SueCT · March 8, 2018

Well, once you bring age and children into it, the advantages of a higher bed increase. I have a raised bed garden out of retaining stones out of necessity because I put the garden on a hill and it levels the garden. One advange I do enjoy is the ease of working and weeding in it Mine is closer to 15-18" high on the down side of the hill simply because that is how much was required to level it off. I have less bending with the raised bed, and enjoy sitting on the stone wall to weed. Those were side benefits, but nice. So going higher will decrease your bending and give the little kids a place to sit on. Should you decide you would like to sit, a 6" top piece could be placed. But if you think you would like something like that eventually, even if not now, make the beds at least a foot or two wider than you think you need to give you room to do that.

bower · March 8, 2018

I don't think you would ever need 10-12 inches if you have soil below the beds, unless you have specific climate issues. The main advantages of raised beds (1) the soil above ground will warm faster and get more warmth from the sun and (2) will be well drained. I have some beds that are 10-12 but they are on top of gravel, no soil below whatsoever.

We have a cold wet climate here but my Mom has raised beds made from 6 inch plank over ground that is pretty good, she can grow anything in those beds including tomatoes. The plank is not cedar, just the regular builder's plank (fir afaik) and without any treatment they stayed good for at least ten years - but that might vary depending on climate as well. That being said, we could probably do better with higher beds here just to get the ground warmer for tomatoes.

2 X 4 is enough to mark a bed, but I think 6 inches is about the minimum to really define a bed well so children and dogs don't run over it without noticing it is not the path. Also the weeds/grass or whatever you have there will quickly swallow up the marker that is only 2- 4 inch high. If you can do the 6-8 inch planks, you won't have to worry about building it up later.

bower · March 8, 2018

Quote:

Originally Posted by SueCT

Well, once you bring age and children into it, the advantages of a higher bed increase. I have a raised bed garden out of retaining stones out of necessity because I put the garden on a hill and it levels the garden. One advange I do enjoy is the ease of working and weeding in it Mine is closer to 15-18" high on the down side of the hill simply because that is how much was required to level it off. I have less bending with the raised bed, and enjoy sitting on the stone wall to weed. Those were side benefits, but nice. So going higher will decrease your bending and give the little kids a place to sit on. Should you decide you would like to sit, a 6" top piece could be placed. But if you think you would like something like that eventually, even if not now, make the beds at least a foot or two wider than you think you need to give you room to do that.

Sue I have a bed like that too in a hillside.

I was thinking about that good reason for really high beds, but TBH a foot doesn't make much difference when it comes to bending.

SueCT · March 8, 2018

The reason for a higher bed bower has nothing to do with soil or amendments, but making it easier to garden as we get older.

Father'sDaughter · March 9, 2018

Mine are 12", but as they are unlined and on soil, I could have gotten away with less. And if like me you adopted a "sort of" square foot gardening technique, you'll be amazed at how much you can actually fit into a smaller area!

Only thing I would do differently if I were building new beds today is I'd make them closer to 3' wide instead of 4'. That reach into the middle with 4' beds is a bit of a stretch and one heck of a core workout! But if you're taller than my 5'2", it won't be as bad.

Gardeneer · March 10, 2018

Since you are building on improved soil you don,t need to build them high.so I would second 6" tall. But if someone wanted toake raised bed on crude native soil I woul say minimum of 12 inched.
On the fimension., 4 by 8 is good. Especially if the lumber is sold at 8ft length. This way nothing will be scrapped and wasted. Of the lber comes in 10ft length than I will make them 4 by 6. Again to to waste anything.
I would recommen walkways to accommodate your eqipments , like laenmower tiller , wheelbarrow

Before I moved here, All I had was taised beds,bacK in PNW. Mine were 3 by 6 because the lumber came in 6ft length. But i jad no more than 12 of them.

TomatoDon · March 10, 2018

I've tried many sizes, and a 5 x 12 with a 5 foot path has worked best for me. For ease of use, for for the older and younger to enjoy, a bed 24 inches high is ideal. There is very little stooping. The problem is having a good supply of cheap, bulk organic matter to fill it with.

One year I bought square bales of hay and used that as my bulk filler. I added bagged organic matter and regular ole Mother Earth topsoil to finish filling it. During the season it will settle, so you will have to add more of everything the next year and maybe the next until you get it stable.

Most farmers will let you have pieces of broken or rotten big round bales that have fallen apart. I see literally mounds of bagged leaves in neighborhoods that also make good organic matter. Some cities pick up leaves and sticks and tree limbs and grind them up and give it away to residence wanting organic matter for their gardens. Just don't try to fill it all with store-bought sacks of organic matter because you will be amazed at how many bags you will need and what it will cost.

I used treated 2 x 12 x 12's. They are safe to use and there is no evidence that I can find otherwise. We've gone over that topic in other threads here for years. I've tried 4 x 8 beds and found them far too small. Again, my best size is 5 x 12 with a 5 foot walk.

It won't be cheap and it won't be easy, but it will be good. You can't beat a properly constructed, sized, and filled raised bed.

I hope this helps.
DS

brownrexx · March 10, 2018

I visited The Rodale Experimental Organic Farm a coupled of years ago and I loved their raised beds. they used no borders. they just raised the level of the planting areas and mulched the walkways in between. here are a coupled of pictures to show you a different style than using lumber.

Nan_PA_6b · March 10, 2018

It'd take a lot more straw than that to keep the weeds down in my garden. Looks like bare dirt showing through in places!

Nan

PhilaGardener · March 10, 2018

If you don't till or turn the soil, it is a lot easier to keep the weeds under control.

March 8, 2018	#1
seymour_man Tomatovillian™ Join Date: May 2007 Location: Indiana Posts: 48	Raised bed question....sort of? Hi All, In my urban garden adventure I have went from couple of rubbermaid totes of heirloom tomatoes to buying a tiller and digging up a 20ft x 40ft garden space. I am on sandy soil and I have approved its structure with organic matter so its pretty decent...not great but decent. I feel that out of my 800 square feet of heaven I waste a lot of space. I garden like it's a farm with 30 inch tiller paths around the edge and between the rows. I estimate I have less than half in plant utilization space. Over the winter I have seriously thought about building raised beds. I think in my garden spot I can actually increase my "plant space" and after the initial investment to build the beds decrease my spending as I will not be "feeding" 800 square feet but only the actual area I use. I plan to build 8ft x 4ft beds out of eastern red cedar. This cedar is not cheap but is very durable. I am not putting anything wire or fabric on the bottom as I want the plants to grow into my top soil as needed. I will fill the beds with organic matter and compost as needed. Here is my question....How tall do I need to make the beds? I understand if I was making these beds as giant containers with bottoms then 1 ft or even 2 ft would be minimum. But with my beds being open on the bottom how high do I need to go? Is 6" or 8" tall ok? As I said cedar is not cheap. I could design it to use the shorter height now and then add another 6"-8" row next year? Any comments or advice is greatly appreciated.

March 9, 2018	#10
Father'sDaughter Tomatovillian™ Join Date: Nov 2011 Location: MA/NH Border Posts: 4,919	Raised bed question....sort of? Mine are 12", but as they are unlined and on soil, I could have gotten away with less. And if like me you adopted a "sort of" square foot gardening technique, you'll be amazed at how much you can actually fit into a smaller area! Only thing I would do differently if I were building new beds today is I'd make them closer to 3' wide instead of 4'. That reach into the middle with 4' beds is a bit of a stretch and one heck of a core workout! But if you're taller than my 5'2", it won't be as bad.

March 10, 2018	#11
Gardeneer Tomatovillian™ Join Date: Feb 2015 Location: NC - zone 8a - heat zone 7 Posts: 4,919	Since you are building on improved soil you don,t need to build them high.so I would second 6" tall. But if someone wanted toake raised bed on crude native soil I woul say minimum of 12 inched. On the fimension., 4 by 8 is good. Especially if the lumber is sold at 8ft length. This way nothing will be scrapped and wasted. Of the lber comes in 10ft length than I will make them 4 by 6. Again to to waste anything. I would recommen walkways to accommodate your eqipments , like laenmower tiller , wheelbarrow Before I moved here, All I had was taised beds,bacK in PNW. Mine were 3 by 6 because the lumber came in 6ft length. But i jad no more than 12 of them. __________________ Gardeneer Happy Gardening !

March 10, 2018	#12
TomatoDon Tomatovillian™ Join Date: Feb 2006 Location: MS Posts: 1,523	I've tried many sizes, and a 5 x 12 with a 5 foot path has worked best for me. For ease of use, for for the older and younger to enjoy, a bed 24 inches high is ideal. There is very little stooping. The problem is having a good supply of cheap, bulk organic matter to fill it with. One year I bought square bales of hay and used that as my bulk filler. I added bagged organic matter and regular ole Mother Earth topsoil to finish filling it. During the season it will settle, so you will have to add more of everything the next year and maybe the next until you get it stable. Most farmers will let you have pieces of broken or rotten big round bales that have fallen apart. I see literally mounds of bagged leaves in neighborhoods that also make good organic matter. Some cities pick up leaves and sticks and tree limbs and grind them up and give it away to residence wanting organic matter for their gardens. Just don't try to fill it all with store-bought sacks of organic matter because you will be amazed at how many bags you will need and what it will cost. I used treated 2 x 12 x 12's. They are safe to use and there is no evidence that I can find otherwise. We've gone over that topic in other threads here for years. I've tried 4 x 8 beds and found them far too small. Again, my best size is 5 x 12 with a 5 foot walk. It won't be cheap and it won't be easy, but it will be good. You can't beat a properly constructed, sized, and filled raised bed. I hope this helps. DS __________________ Zone 7B, N. MS

March 8, 2018	#2
SueCT Tomatovillian™ Join Date: Jan 2012 Location: Connecticut Posts: 1,460	Even 4" would be fine because you are actually planting in the ground not in beds. So the depth doesn't matter, the plants are not limited by the depth at all. But not exactly sure what you will accomplish. You could just amend the soil around the plants themselves instead the entire garden and accomplish the same thing. If you want to provide a barrier, in order to contain mulch or amendments, you only need to make it as deep as you want to make the amendments. But remember they will fill up quickly. Consider how deep you have good amended soil already and how deep you want the final amended bed to be. Add a raised bed that will give you the final depth you want. Is that what you are trying to do, is use less material? The roots are still going to spread out below the sides of the raised bed in the ground.

March 8, 2018	#3
eyegrotom Tomatovillian™ Join Date: Feb 2018 Location: So Cal Posts: 380	Hi I agree with Sue 2x4 or 2x6 will work. If all you want to do is basically cut down on the area that you feed or amend, Mike

March 8, 2018	#7
bower Tomatovillian™ Join Date: Feb 2012 Location: Newfoundland, Canada Posts: 6,794	I don't think you would ever need 10-12 inches if you have soil below the beds, unless you have specific climate issues. The main advantages of raised beds (1) the soil above ground will warm faster and get more warmth from the sun and (2) will be well drained. I have some beds that are 10-12 but they are on top of gravel, no soil below whatsoever. We have a cold wet climate here but my Mom has raised beds made from 6 inch plank over ground that is pretty good, she can grow anything in those beds including tomatoes. The plank is not cedar, just the regular builder's plank (fir afaik) and without any treatment they stayed good for at least ten years - but that might vary depending on climate as well. That being said, we could probably do better with higher beds here just to get the ground warmer for tomatoes. 2 X 4 is enough to mark a bed, but I think 6 inches is about the minimum to really define a bed well so children and dogs don't run over it without noticing it is not the path. Also the weeds/grass or whatever you have there will quickly swallow up the marker that is only 2- 4 inch high. If you can do the 6-8 inch planks, you won't have to worry about building it up later.

March 10, 2018	#14
Nan_PA_6b Tomatovillian™ Join Date: Dec 2016 Location: Pittsburgh, PA Posts: 3,194	It'd take a lot more straw than that to keep the weeds down in my garden. Looks like bare dirt showing through in places! Nan

March 10, 2018	#15
PhilaGardener Tomatovillian™ Join Date: Jan 2014 Location: Near Philadelphia, PA Posts: 1,940	If you don't till or turn the soil, it is a lot easier to keep the weeds under control.