Any brilliant ideas to solve this

[Lambside]

Hi, after my landlord not dealing with the issue very well the owners of my neighbouring property have replaced the fence between us. It's a very good, solid fence well put up and I love it but.....the property where I live is built on a higher level than next door and whereas the old fence sat atop some crappy concrete that shores up my garden the new one is built on next doors ground level and there is a gap between.
Not only that but the soil level in my garden goes from level to the crappy concrete at one end to about 10inches higher at the other end and it will all make it's way down the gap.
I hope I'm making this clear, if anyone is actually still reading.
I can't decide what if anything I should do about this. I've sent photographs to the letting agent but I know the landlord won't want to spend any money.
I could lower the soil level which would take a lot of hard work digging, disposing of the soil, digging up plants and replanting them etc.
I could try and put in some kind of barrier at back of crappy concrete to hold soil back like slates maybe? It's very uneven though and presumably slates cost money too.
I'm a bit flummoxed. The first heavy rain will have half the garden washing away down the back of next doors fence.

And rotting their fence, too.

How wide is the gap?

It varies from maybe 5-6 inches to quite close in places. That's because of the crappy concrete meandering about.

pic

You could build up the beds next to the fence (on top of the concrete) with sleepers or raised blocks?

What would keep blocks in place?

Gravity! Or you could concrete on. Railway sleepers would do the trick but it is a money.

I've got something similar in my garden. The houses behind are lower and abut my garden, with a narrow gap and then a retaining wall which retains my garden. My border is higher than the top of the wall, but it's well planted and doesn't fall into the gap at all. When I weed it I just make sure to redistribute any soil that is getting too close. It's really not a problem.

So planting might help?
Hmmm what would be good to plant to be there all year and make growth and roots to hold it back? Something low and bushy? Tall and bushy? Tall and flat?

It's not good news for his fence!

No it's not! And I love the fence.

@Lambside

So planting might help? Hmmm what would be good to plant to be there all year and make growth and roots to hold it back? Something low and bushy? Tall and bushy? Tall and flat?

I've got ferns and a supposedly dwarf buddleia in mine.

Is it sunny, or shady?

It gets the sun early morning, then late morning till late afternoon from say march to september. Surrounding houses and low winter sun keep it in shade the rest of the time.

There was a biggish lilac in the pictured corner when I moved in.

I have London pride - it's an evergreen plant about 3 inches high with little flowers in spring. It might be a bit sunny but it's a ground cover plant. You would need quite a few plants but it's tough.
Pulmonaria is another one. Though I don't think it's evergreen. Again ground cover but I'd think they'd stop the rain washing soil away.

I'm thinking hebe maybe in a section of hedge type planting. The other bits where the soil isn't so much higher already have pretty established shrubs.

Just got some London Pride last year after searching for ages! It's still in it's pots as I'm afraid to plant it out. Lots of plants do badly in that spot for some reason hence why it is pretty bare at the moment.

London Pride might well like it there.

Various mossy saxifrages should like it, and spread along.

You could try one of the geranium macrorhizums, they are semi evergreen. Creeping phlox or creeping thyme too.

Ajuga (Bugle) is another possibility.

In places like homebase, Wilco , B and M etc I have seen rolls and strips of plastic which are supposed to stop borders leeching into lawns. I don’t know if it would work in your situation by putting the strips at the back of the border to stop the slippage. The gap would still be there but it might stop your soil disappearing. It wouldn’t look very beautiful , but in summer at least it would be covered by pants.

It's always good to stop slippage by covering with pants!
I've been out and got some shrubs for that corner. Larger than London Pride but that can go toward the front of the border. I got two Hebes and a Viburnum. Plus massive result! I raided the fence builders skip of rubbish and found two decent lengths of gravel board which I am going to try using to keep soil back. I'll fashion some stakes to attach and thump them into the soil behind crappy concrete hoping crappy concrete doesn't crumble

looking at that I would be tempted to stand large planters on the concrete along the fence.
Then get some planks, from say B&Q, paint them with fence paint. Cut to whatever length you need.
Then dig a trench in front of the pots, deep enough for the plank to sit at half depth, and place it in.
Then back fill with the soil.
This should create a buffer to stop the soil eroding away into the neighbours. Then you can use the garden as you wish.

We did something similar with the garden as it slopes downwards. We wanted a gravel section, but it would have gradually spread into the grass. So bought planks from B&Q and did just what I suggested to you. (see pic).

@Lambside

It's always good to stop slippage by covering with pants! I've been out and got some shrubs for that corner. Larger than London Pride but that can go toward the front of the border. I got two Hebes and a Viburnum. Plus massive result! I raided the fence builders skip of rubbish and found two decent lengths of gravel board which I am going to try using to keep soil back. I'll fashion some stakes to attach and thump them into the soil behind crappy concrete hoping crappy concrete doesn't crumble

Hoiks knickers to a safe height to ensure slippage doesn’t frighten any passing horses.

Quick question-should I be worried about hedgehogs getting trapped in the gap?

The concrete looks very non crappy to me .I mean it's not lumpy or disintegrating .

Anyway ,I second planting .The roots will hold the soil in place .I have sweet woodruff in similar areas ,it's low ,evergreen ,spreads by runners .Can be invasive .