Greenhouse drainage

Redcross

My greenhouse floods with heavy rain. I have been told that I need to remove the two rows of bricks that are positioned against the greenhouse base , dig a trench and fill with gravel.
I'm looking for guidance on how deep the trench should be and should I use 10 mm or 20 mm gravel.
Any advice would be gratefully received.
Thank you

twopenny

Red cross I can't answer your question, I'm still hoping for a greenhouse one day.
But it sounds a reasonable idea and quite simple.

Can you post a photo of the greenhouse in it's setting we could have a stab at it.
We have one person at least who should know. Probably more will drop in.

Or you could ask for your post to be moved to the DIY form where I know they know about gravel and drainage 

Redcross

Thank you, I'll do that

MartinGardener

Hello
Many people think greenhouses are supposed to be water tight, but as you know, they aren't!

Simply put what you need is somewhere for excess water to escape from your greenhouse. This is for when it rains or when you're doing a lot of watering in the warmer months.
Remove a brick from your greenhouse base and replace it with a half brick or drill some holes in your bricks.
Check if there's a slight slope the water is running down and let the water flow out of your greenhouse that way.

Hope that helps.

Dustyevsky

We can't answer a question like this without context. 

I know a garden that floods regularly at one end in winter to a depth of 5cm or so. No amount of trenches would make any difference if there was a greenhouse involved, because there's nowhere for the water to drain; it's a typical developer-made issue covering several gardens. The solution in that case might be to raise the greenhouse floor about 10 cm. However, that still wouldn't be ideal. The best solution would be to put the greenhouse in a more suitable place! 

DD265

Appreciate I'm late to the party, but what you're describing sounds like a french drain.

We put one in at the allotment; because we're on clay soil, we dug down, put a bit of sand in, put a plastic gutter down (it sloped very slightly towards somewhere water could run off) and then filled the gutter with pea gravel. As long as the stones allow water through it doesn't matter.

In the greenhouse itself, I dug about a foot worth of clay out, made raised bed edges out of planks of wood (they're about 4" tall) then filled with better compost. I'm planting a pomegranate soon and I'm going to cut the base out of a trug or decent size pot, rest that on the soil, fill it with soil and then plant the tree, so it's not sat in water all the time. Admittedly I only put the edges in last year, but over winter I never noticed any water pooling whereas previously it'd be under an inch or two in the corners particularly.