Help! Waterlogged raised bed killing plants

jenniferavril

We live in a new build and have had significant problems with waterlogging in the sloped garden. After extensive, very good and well executed drainage which is connected to the waste water pipes (including a silt trap), flagging the worst areas and building raised beds around the edges, it seems there is still a serious problem at the bottom of the beds/slope. The natural earth beneath is compacted clay but the beds were filled with high quality soil, but are now drenched. We get a lot of water from our uphill neighbours, especially since they flagged most of their garden and put plastic grass on the rest.

At the weekend I dug up the mature evergreen fern I'd planted at the end of summer to try and drink up some of the moisture, but it had died. When I pulled it out, it was clear why (see pics). It came out complete in one pull with a suction noise because it was soaking wet. What on earth can I do about this, given there's nothing more we can do to improve drainage and the conditions are clearly far too wet for plants as it's now just standing water? The hole is maybe only half a foot deep, if that. Seems we've wasted a lot of money on these beds. 

Busy-Lizzie

Are there any drainage holes in the bottom of the beds?

You could plant plants suitable for bog gardens!

jenniferavril

Yes the beds are just straight on top of the original earth with no liner at the bottom. I looked into bog garden plants, but everything I read said even they don't tolerate standing water! Pulling my hair out! 

floralies

I was going to ask the same question. Bog garden plants would seem the way to go if you can't improve the drainage anymore.

jenniferavril

I'll look into bog garden plants again then. The small plant next to the hole is a sarcococca hook, which is doing ok now but I suspect will also die when it matures. The heucheras were all planted for the conditions too. All were recommended by the very knowledgeable bloke at the garden centre after I described the state of the earth and low sunlight in that area. I suspect the higher up the slope the beds go, the less waterlogging there is. 

jenniferavril

Full length of the bed, gives an ok idea of the slope but I'd say it's a bit steeper than that in reality. Flagged area with bins directly next to the bottom. It's clear from the wet wood how much water is there.

B3

Have you got drainage gaps at the bin end of the bed? If you have, at least some of the water would drain out. I would be a bit concerned enough the fence rotting too.

bédé

I think there is no easy solution.  Taking out all the soil and adding drain holes is my only advice..

jenniferavril

Yes the whole of the bed is built straight on the original earth. I am also concerned about the fence rotting, but I've noticed seemingly the whole town is covered in algae this year. I'll be treating all the fences and beds this spring. Our very good landscaper suggested a sump pit in that area if we continued to have problems, which is yet more money and more work. 

Dovefromabove

As well as drainage holes, some hardcore and gravel in the base of the bed, before adding the compost/soil, would aid drainage. 

jenniferavril

To try and give an idea of drainage (don't know how to rotate first photo) - there is some under that bed but it starts about halfway down, all the pipes are connected together and into the main drain. Water still collects in that corner at the bottom behind the gate despite there being further drainage downhill of it. Is there a way to add a pipe at the bottom, given I've nowhere to connect it to? This was done June 2021.