Forum home Fruit & veg

Greenhouse beds

Steve 309Steve 309 Posts: 2,753

I'm responsible for a large greenhouse (30 x 20 x 12 feet or so) with lots of (movable) benches but no soil beds.  The floor is concrete and the dwarf walls are breeze blocks on the inside and brick on the outside (so probably a cavity!)

What I thought of doing was building another dwarf wall parallel to a long side and filling the gap with soil/compost to make a lot more growing space.  The likely size woud be about 20' long by 3' wide and as deep as I have soil for - probably about 2'.  If it works I could replicate it on the other side.

Is this a good idea?  The two pitfalls I can forsee are overloading the concrete base and adequate drainage.  Any ideas?


  • Chris 25Chris 25 Posts: 50

    Hi Steve, you made me green with envy i wished i had a greenhouse your size i would never be out of it.image

    Now regarding you soil beds, you can do no wrong in in building your beds as you said however before the soil goes in excess water needs to escape, i am presuming you may have a concrete floor, sorry if i am wrong, i would only try one side to start with doing both sides will thwart any ideas you may have to grow other plants from cuttings and seeds, so i would think seriously about doing both sides.

    20foot x 3foot bed is a large area for cucumbers tomatoes, and other plants i am wondering are you planning a commercial venture there.image

  • Steve 309Steve 309 Posts: 2,753

    I run the garden for a homeless men's hostel, and the greenhouse was built with some sort of grant several years ago.  I tend to be there about two days a week (although they only pay me for 6 hours!)

    As I said, the floor is indeed concrete - do I need to break it up I wonder to allow drainage under the bed and build a foundation for the dwarf wall? (It'll be builders' rubble and sandy subsoil underneath).  I shall certainly start on just one side and see how it goes; there'll also be room for a bed each side and plenty of bench space at the ends and down the middle.

    It looks like being semi-commercial in due course - someone's taken it into their head to create some sort of enterprise scheme to sell produce, hanging baskets etc.  Not quite what I had in mind originall but if all I have to do is grow stuff....

  • Chris 25Chris 25 Posts: 50

    Hi steve,

    hello my friend, yes you do need to lift concrete up so you have drainage, but don't do it all yourself your retired so why kill yourself when they only pay you six hours work

    don not worry about the sanding soil once the concrete is away the sandy soil will help keep moisture in the new soil  when your not there to tend to it.

    steve if you would like an idea how to set up an automatic watering system let me know i have a cost effective way of doing it

  • WelshonionWelshonion Posts: 3,114

    Stop!  Think carefully before you break up the concrete base.  I have a raised bed lined with pond membrane in my greenhouse and I find it dries out pretty fast.  If you are only there twice a week, who is going to water on the other five days?  I water my tomatoes every day.  They are in bottomless pots on a bed of fine stone/gravel.

    Before you go breaking up the concrete, take as much advice as this forum can offer you.  So far you have only had two views!

  • hogweedhogweed Central ScotlandPosts: 4,025

    I would not break up the concrete base but put about 6 inches of rubble/gravel in the bottom under the topsoil and seep holes in the bottom few courses of bricks. Any surplus water will then seep out into the middle of the greenhouse and evaporate in the warm weather.

    'Optimism is the faith that leads to achievement' - Helen Keller
Sign In or Register to comment.