Advice needed: building raised beds over concrete

Hi permies!

I am planning a major project this autumn - to build large raised beds for growing vegies.

However, there are some challenges:
- I live in a garden apartment, and the yard is mostly paved over, therefore my new raised beds must be built over concrete
- I live in Israel, a full-blown Mediterranean climate. Scorching sun and no rain 7 months a year. We have drip irrigation but water retention will be a huge issue in a raised bed over concrete. I understand that hugelcultur is not a good option in such a dry situation
- Given that sun exposure changes so drastically in a garden apartment at different times of year, the beds should be somewhat movable, Like two strong people could move them a few meters across a tiled surface
- Even though the beds will be disconnected from the earth, I would still love to approximate a living soil ecosystem as much as possible, with soil life that is helping me out

Since we will be investing much time and money in building these raised beds, we'd love to not have to learn everything the hard way!!!

So dear permies, I am looking for the following tidbits from you:
1. If you have undertaken a project like this before, can you please share your experiences and tips for success
2. can you recommend building materials and plans for creating raised beds of this type?
3. Any other helpful or supportive comments are welcome!

Thanks!

The beds I built can't be moved, but they are built over concrete.  It's worked great for me every year, and it's like a jungle in my backyard right now.  I live in the southwest desert, and there really hasn't been any measurable amount of rain for months.  I don't know if we've even had an inch of rain this year!  I use drip emitters and water with city water 3 times a day right now (it's been 100F the last week, and will get about five to ten degrees hotter for the next three months with little to no precipitation.  
My beds are filled with earthworms, I spotted baby preying mantis today on some leaves, and there are ladybugs around but not a lot.  I also heavily mulch my compost with fine wood shaving from my woodchipper.  There is also a network of fungus below the surface.

Here's a thread I did about it a few years ago. https://permies.com/t/40/134151/filling-raised-beds

Here's another thread I did showing the progressive steps to turn a backyard concrete driveway into an urban food forest.  It's the same as the first thread, but it really shows before and after better.   https://permies.com/t/135737/Urban-concrete-driveway-evolution-Lot

Good luck with your project!

thanks Joshua.
I read through all your threads and learned a lot. I really appreciated all the detailed photos you took!
If you have plans of how you built those boxes that would be so helpful. We would like to try build something similar!
Thanks again!

If you are going to have to move your garden, might this be the ideal circumstances for container gardening!  I can only guess how heavy a full-blown garden bed would be and how difficult to move, but a series of buckets or other containers makes that a much easier process.

Just a thought,

Eric

One of my garden 'beds' is actually a large cedar bin on locking wheels with a treillis backing. It serves to close off the end of my driveway and hide the garbage cans behind.

Inside the bin, I have three deep self-watering containers which fit perfectly. It's heavy, but it can be rolled fairly easily, or I can take the containers out one at a time if needed for maintenance.

It's probably not a very economical solution if you need a lot of bins, but it's a very esthetical one.

I've also been part of a rooftop community garden that had large self-watering containers made out of plastic pails and Rubbermaid containers. It was able to withstand very harsh sun and wind conditions (they built a pergola to create some shade over part of the garden). It can scale up well and makes for a very flexible setup, but it's not as nice looking, obviously.

And in real life (with kale and beans)

I really like Joshua's raised beds as they look nice and halve a good depth to them.

I also like Eric's idea of using containers.

Why not have some of each?

Are you going to make the raised beds small enough so that they will not be too heavy to drag around?  I wonder if wheels could go on the beds to help move them.

Our raised beds are just four boards put together with screws.  Ours is about 5 feet by 5 feet because we used ten-foot boards cut in half.

It might be more expensive though to me 2 feet by 4 feet might be easier to move.

I hope you will share your project in a step by step instructions so others can learn from your project.

I have some ~4 ft by 6 ft raised beds that are made out of salvaged shipping pallets that are 30" high. I put a lot of punky wood in the bottom and that goes a long way to holding moisture, but we don't have the sort of weather Bloomah is describing.

I also took some plastic shipping barrels and cut them in half in the round direction. The modern barrels are wimpier, and they don't stay round at the top, so I get broken bicycle wheel rims, cut them to fit and bolt them to the top edge. (Both the wheels and the barrels tend to differ in size - sometimes I go inside, sometimes outside and I use #8 stainless hardware with fender washers against the plastic.) I drill drainage holes about 1 1/2 inches above the bottom in 3-4 spots, so they can't end up flooded. I try to get black ones so the roots are kept darker. I've got several that are over 15 years old and still fine, but I suspect my sun isn't as intense. However, with a sturdy dolly and a strong person, they can be moved. They end up about 18" high and are approximately 3 square feet of planting area.

My biggest complaint about most raised beds is that they don't contain enough soil to help them hold water. Coconut coir is a big help if you're in a region that produces coconuts, as it helps to hold water. I've heard the same about biochar if you can access it.

Joshua Bertram, how many inches tall are your metal/wood raised beds?