Raised beds in concrete

[KatyN]

Hello. I'm new to this board but wondered if anyone could give some advise?
We have a carport at the back of our garden that is never used for cars. I would like to grow vegetables on there, probably in raised beds. I thought the concrete would be brilliant for the areas between the beds but I'm not sure how deep the beds will have to be for the plants?? There isn't really anywhere else I. The garden for the veg patch and I'm loathe to dig up all the concrete because we'd like to put a shed there too,
Is this a ridiculous idea??
Thanks Katy

A true raised bed rests on the soil beneath, but what you need is a giant container. This link is Australian, but I'm sure they do this kind of thing in the UK.

You need to look at which plants do well in containers: tomatoes, lettuce, rocket, radish, the list goes on.

www.bunnings.com.au/our-range/garden/landscaping/outdoor-structures/garden-beds

We grow all sorts in our raised beds.......filing cabinets!

Get an old filing cabinet, remove the drawers, drill holes in bottom, spray paint, fill with soil ( we used bark chippings for bottom 4 inches to save money) et voila!

We grow loads in ours. I have a root vegetable one, a salad one, a herb garden and a nursery

Sounds like a good idea and you could get lots to grow, but I second that you need to think of it as a set of enormous pots and to factor drainage into them in a way that won't leave muddy staining water running all over the concrete. We have a very high raised bed ( 4 railway sleepers) but that was to suit the look of the area not for depth of soil. Most of it is actually big rocks at the bottom and then smaller gravel on top and then soil- probably only 1.5 of the sleeper depth. We bought top soil from a builders merchant as we needed so much ( hadn't really thought it through at the start to be honest) and horse poo locally and some compost and mixed it all in. Every year I dig in more poo and leave it empty over winter with a weed membrane on it. I'm thinking of putting in some of those watering pipes into it this year before I plant it up as it does take some watering and that's something else to think about. Can you put a water butt in or do you have easy access to a hose? If you want to grow things like peas and beans think about the shape of the container so you can easily incorporate supports eg a rectangular container could have wires set up to run along the back, or a circular one could have a central support. Have you got any walls round the area? If so you could grow tomatoes or strawberries in wall mounted pots? It could be a really lovely busy pretty area. I chuck in nasturtiums every year as they are so cheerful and I like the leaves in salads but they do self seed like a bugger. Had success with spring onions, lettuce, peas, beans , chives and parsley. Carrots were a bit rubbish but I think you need a sandier soil for those. Some plants don't play nice with others and done help each other so it's worth looking up ' companion planting' before you start. If you have lots of containers you could separate things out. Sorry if that's too much info- just re read and realised you are only really asking about the concrete issue!

I use these for cucumbers and tomatoes.

www.abc.net.au/gardening/stories/s3885151.htm

Harrod horticultural do some good, fairly inexpensive raised bed kits. I have one in my front garden, as the bedrock is only about a foot down. One word of warning: you need a LOT of topsoil and compost to fill them. This was OK for me because I was digging out an equivalent area of my back garden, so it was free. It would have cost a hundred quid or more to buy that much soil.

In your shoes, I think I might consider costing out both options. How much is it to put up a shed and buy a bed and fill it, and how much is it to put up the shed, then break up the surplus concrete with a mattock and hire a skip to bin it. My guess is that the latter might be cheaper. The soil underneath the concrete will need lots of improving with compost and horticultural grit, so cost those in, but it means you can grow in the ground.

Toooldtobearsed- I love the filing cabinet idea!