Another problem would be drainage, if the beds are sitting on concrete the water needs to drain out of there....sally

Large raised beds -- GOOD.

Beds of any sort with concrete underneath them -- BAD.

You COULD grow roses in very large containers, with the containers raised up off the ground by "pot feet," to allow free drainage ...

But I have to tell you that I have done this, and the roses never really matured and did well until we gave up, and put them into the ground -- whereupon, they took off like a shot..

Jeri

I have a question for Jerijen.The bed I have chosen takes drainage into consideration. You didn't really address my question. Has anyone ever tried a raised bed of this size, (with good drainage, of course) There is approx. 60 cubic feet of soil in each bed.

My whole garden is a pot garden including 2 large 'borders'. You will need to have a depth of around 50-60cm (up to 2feet) and most importantly, you will need to include many 'weep holes' at the bottom of the bed wall for water to run freely....or you will end up with a swimming pool. Drainage is the major concern so your soil mix has to be carefully decided - I have a mixture of grit, loam (with a portion of peat, I am afraid) and added humus in the form of continual topdressings of compost. Potting mix will NOT do - you will have to get decent top soil. and have a base of 4inches of gravel or crocks. Even then, it is fraught with problems (and I have the list of fails to prove it).
This is not to say it is impossible - there are many plants with shallow roots and a desire for excellent fast moving drainage (alpines for example - although I cannot recall where you are posting from so this suggestion might be laughable)). Be prepared to experiment and take a few losses but as always, there is usually some way round these problems with a bit of ingenuity and a high threshold of tolerance for disaster.

It can work. There are rock sheets 16" below the surface of raised beds in some areas of my garden Your beds would be like planters. You do need drain holes every 3-4' around the margin, and you could connect them to perforated black plastic drainage pipe crossing the bed. I would not use a drainage layer at the bottom. This would just raise the inevitable saturated zone higher in the planter. You need a sandy loam soil, around 80% sand including what is already in the topsoil. You can check the sand content of the topsoil (google soil jar test).

Andrea,
it seems to me that if you are in zone 9, the concrete in the summer would hold heat and that is not a good thing.
You are focussing on planting on this slab because you say it is the only sunny spot left.
Could you go in another direction and perhaps have some trees trimmed for more sun?
Or could you hire a crew with machinery to break up and remove the slab?

This post was edited by lucille on Wed, Mar 27, 13 at 11:03

If you're planning to put a raised bed there anyway, why not break up the part of the concrete which would be under the center of the raised bed, and leave the perimeter as a base on which the raised bed would rest? Basically, you'd make the slab into a sort of picture-frame shape. That way, you wouldn't have to worry as much about drainage. If you left a wide enough rim of cement around the outside of the raised bed, you could then arrange pots around it.

:-)

~Christopher

Why not? Make sure the water can drain is all I would worry about, that and enough support for the walls of the beds that they don't bulge out too badly.

Wow! Thanks for all the great advice.

I will have to consider it all. But my (in ground) babies are soooo gorgeous that I am worried that the raised bed plants won't be as good.

If i had some of cement taken out, I wouldn't need a raised bed at all.....Cost is something to consider.

I understand cost of taking away the cement is something to consider, but you may be able to do it more reasonably than paying for the materials, soils for the raised bed. I would take some pictures and get a few quotes you may even find someone who will break it up for a couple or few hours of labor time then you could clean it out and haul it off. I just think you would be happier overall in the ground. Doesn't hurt to ask!

Correction, You would be happier if your roses were in planted in the ground! What can I say, long day of work, lol. Sorry Andrea!

You might put an ad in your local paper or swap shop publication - for the free fill concrete - "break and take" so to speak - you never know who might need some filler for something....never hurts to put your request out there! We have a paper called The Peddler and I have never ceased to be amazed at what I can sell in it. I am no expert like most of the people who are answering you, but it would be a shame to haul in all that soil [I just got finished hauling great soil in for several beds] and have it to not work. The only other suggestion I could make is for someone with a jackhammer to come in and punch lots of holes for drainage in the slab. But that still might not work. Or....make a patio out of the slab and cut some trees.......Were it me, I would put out a "free" ad first - if that didnt work, get bids on taking it out. Then do the bed. My dad taught me something that has always served me well - do it right the first time, then you dont have to redo. After just finishing hauling all that dirt [and more to come for some new beds] I would certainly not want to do that unless I knew the bed would work. Good luck! Where there is a will, theres a way!
Judith

Personally,

I would check on the amount of sun the zone around the patio gets and then consider trying a couple of roses in big pots on the patio and seeing how they do.

As some one that has broken up thick concrete...it is not nearly as easy as you might think and while yes you see people advertising free concrete chucks, I also see them listing them day after day after day often for months. Also, you could be liable for any injury to them and get the bill for damages they do accidentally (if you need a new patio door this might be one way to get one)

i vote for breaking it up, but if not, do check out the costs first for the raised beds, i have done several and they DO add up!! good soil at $40 a cubic yard, delivery, border, etc.

Wonder if you do stay with the concrete, A. drill holes in the concrete? B. bury on the bottom a kind of french drain system, with pea gravel and/or black perforated tubing with a large diameter, so that the bottom few inches acts as a french drain.

Don't know your long term goal, but....it usually PAYS to do it right the first time rather than forever try to improvise...and too, add on the 'cost' of your joy and pleasure at the garden!! I know I will FOREVER ruminate on wishing I had done it the way I REALLY wanted it the first time...but that is just me.

I do think the french drain system would work. it might drain a little TOO well and require a bit more water.

but i promise, measure out the cubic footage of soil needed and you may be staggered at the cost!!!! easily $40 a cubic yard plus delivery fee and manpower fee to move the soil from the big dump in your driveway to the bed....$$$

good luck!!! something will work out though and you WILL have some pretty roses!!!

I am a DIYer for many garden and home tasks. I had a tree in the front yard that shaded out the place I wanted for roses. I bought one of those tree trimmer saws for about $30 and trimmed the branches.
Maybe for very little $ you can get more sun and not have to deal with the slab.

I ran out of sunny spots and did just what kitty suggested. I potted up the roses and put them on the patio. It is more work to winterize them but it's actually easier to care for them through out the season and I can move them around as needed to get optimal sun.

The broken up concrete is called "urbanite" nowadays and is quite trendy.

it usually PAYS to do it right the first time rather than forever try to improvise...and too, add on the 'cost' of your joy and pleasure at the garden!! I know I will FOREVER ruminate on wishing I had done it the way I REALLY wanted it the first time...but that is just me.

It's me, too--in my experience it always pays to do it right the first time.--but for various reasons not everyone takes the long term view.

Is the concrete area useful for anything, or is it just a random concrete area? Have you thought that it might be cheaper to just trim some trees to get more sun in other areas?

My head is swimming with all the suggestions....

Thanks again for all your input. After reading all messages, I think I will probably have a chunk of the 'patio' removed. I have a 15 by 35 deck that I use
for 'hangin out'...So the large cement slab is just there.

I will send photos of my first babies. And will also send photos of the new bed. (Will probably be about 4 or 5 months from now.

You are all great!

On the remaining part of the slab, get a few (?) large decor pots and put mini's and minifloras in them. This way you can walk down the middle of the slab with rose's on both sides.

You could hire a Kango hammer and break it up yourself - lots of noise and dust but also quite good fun - as long as there are lots of beers afterwards.
You don't actually need to remove all the concrete, just break it so you get some movement of water (drainage).
If you go that route, you may need to adjust for the increased alkalinity of the soil.