Walled lawn area drainage question

Hi all

First post and my apologies in advance if I have posted in the wrong section.

The question I have is, I recently bought a house which has no lawn area, instead it surrounded by paving on top of a thick (aprox 110mm) concrete base.
I thought about creating a rectangular walled section into which I would like to plant some grass but obviously drainage is a concern.
I have attached a sketch showing what I intend to do.
Did lot's of research and this seems the correct way of going about it but I am unsure as to where the drainage holes should be with respect to the different layers (see sketch).
If too low, then surely the sand will come out with the water and if too high it may be ineffective.
Would appreciate any input/thoughts/suggestions from the community as to the placement of the drainage holes, their diameter and spacings and any other points which may be relevant.

Thank you in advance.
Dave.

 

I don't think it will work - happy to be proven wrong though.

I would go with Astro turf - good versions look really realistic

Either than or rip up the concrete and return it to being soil etc., but the soil under (when you find it) will be sour from having had no air for years, so you'd wind up needing to get some air into it ... and then put (probably quite a lot of) topsoil on top. Big job.

 

Hello and welcome Dave.

Sorry, I'm inclined to agree with Kristen. I can't see it working. Here's why:

Firstly, there's the proposed soil depth. In your diagram, you seem to be saying that the total depth of the raised area will be 220mm, and only some of that depth will be soil. I think it will become waterlogged when it rains and bone dry in summer. Neither condition is good for grass.

Then there's the positioning of it. It appears to be sandwiched between two high walls, between the house and the wall on the left of your diagram. I'm going to guess, without knowing which direction it faces or whether there is another wall 'in front of' of the diagram, that the area in question is in almost permanent shade, which again unfortunately is not good for grass.

I think if you go with your original plan, the grass will germinate and get away, but will be in such unfavourable conditions (for grass) that moss will quickly take over and you'll be in for disappointment.

Doom-mongering aside, I like the idea. I just think you face a few extra challenges to make it work. Done right, you'll be doing your bit for the environment as much as yourself, as quite apart from turning a concrete area into a garden with the obvious benefits that brings, it will also lock up a lot of rain water that would otherwise contribute to overwhelming the drains during heavy rain (and we've seen plenty of that happen recently).

What do you want the lawn for? Will it see a lot of activity from kids playing, grown-ups having a bbq etc? or is it just ornamental so you're not looking at concrete? Does it have to be a lawn or could it be a flowerbed/shrubbery/pond? Is it a formal design because you like formal, or just because that's what seems to fit?

There are lots of ground covering plants that are far more tolerant of adverse conditions than grass, but perhaps not so great for walking on. Or there is astroturf as Kristen suggests. It really depends on what you're ultimate goal for the area is.

 

I looks to me like it would only be a narrow strip of grass and then as Clue says you would be dealing with a lot of shade. I don't think grass in this location would be a good plan either. I'd be tempted to sack the grass idea and grow some shade loving plants in attractive pots and keep the paving.

 

Pots are a great idea. Its one of the reasons I like 'yard gardens' as I call them. Its nice to have a decent sized garden but they have drawbacks. With a container garden there is one very significant plus point. Plants put on their best display at different times depending on what they are. With containers, you can move them about, put plants that are not particularly at their best in low profile position and bringing the best ones to the fore, then when the best ones start to go over, you just shuffle them again, so you're always showing the plants when they're at their best.

Another plus is that if disaster strikes and bindweed or a disease gets in, it is far easier to isolate and quarantine plants in containers than it is to try to work round them in open ground.

 

Hi and thank you for the responses.

@Kristen
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As regards using astro turf, I am worried about a certain careless smoker in the house and also of course one would have to be very careful as to where the Sunday BBQ would take place
I did think about ripping up the concrete, but a slab 20m long, 2m wide and 100mm thick would be a nightmare to remove.
I suspect that it's not one solid piece, but still the cost of breaking it up and removing the rubble would be prohibitive.

@clueless1
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Yes I was worried about the 220mm depth myself so went past two garden centers and asked what the minimum soil depth for grass is and the answers I got were pretty much:
"Uhmmm, well, errr, it depends on the grass type".
So I will have to investigate further.
As to your very valid point of the area being in constant shade, it turns out that roughly the first half (from the perimeter wall to about 1m in) gets sun from about 8am to around lunchtime and as the afternoon rolls in, the other half gets sun until around 4.30pm after which the house gets in the way (this applies in summer).
I don't know about winter as I had the idea only after recently purchasing the house.
The house is north facing and I am in the southern hemisphere.

I will have to choose a grass type/variety that can cope with these conditions along with some mild frost for a week or so in winter.
Average summer temperatures are 28 - 35 degrees Celsius and in winter, they can drop down to -2 in the night but then during the day the average is around 12 - 16 degrees.
Only had snow twice in 30 years and then it was only a small amount.

@Fern4
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I did consider the pot idea but the concreted area would still be visible and it's really, really ugly and would like some grass for the kids to play on.

What I didn't include in my initial post (simply because I didn't know about it) was using French drains.
I did lots of reading and suspect that it may just work, two sketches attached.

Comments and suggestions would be very welcome.
Dave.

 

So we've established that it will get some sun. Probably enough for most lawn grasses, but now I realise you're not in the UK, your summer time typical daytime temps are what I'd consider a major heatwave. Grass is going to need a lot of water in temperatures over lower to mid 20s C, otherwise it will be yellow within a day.

That problem will be exasperated by the lack of soil depth, as its just not deep enough to retain a lot of moisture in hot weather.

What about something like a pebble garden, with a few low maintenance, low growing evergreens planted in it. There's something like that at my old work and it looks really good. Can't show you that because I don't work there any more, but I found something that shows similar ideas:

http://www.gardenista.com/posts/10-easy-pieces-stepping-stones-and-paths-pavers-gravel-pebbles

Something like that will maximise the available light by using the light pebbles to reflect the available daylight, will be very low maintenance compared to a lawn, cheap and simple to build, and pretty much immune to whatever the weather throws at it. And if you accidentally knock the barbie over (as can happen), you don't end up with a burnt patch that takes weeks to recover

 

Great idea clueless1, I really like it.
Also found a fantastic garden bench design on the same site which I'm now thinking of building a couple of against the perimeter wall.

 

Right, the "boss" has just seen the suggestion by clueless1 and it's official, I have been duly instructed to build something similar.

Thank you for the great suggestion, looks very nice and may just save me loads of work.

 

I love the garden bench design...it's really clever. You will have to show us some before and after photos.

 

Cool. I guess the next step is to work out what plants you like, that will be happy in those conditions. There'll be plenty to choose from. Maybe think about colour schemes, how much effort you want to put into looking after them, whether you bold or subtle etc. Maybe also think about lighting and water features. Now is the perfect time to think about those things, as you haven't built it yet so you could get the infrastructure (cables, pipes etc) in from the outset without disturbing anything.

A good example of water feature I like, that would probably work well for you, is @Bilbo675's 'pond in a bucket' project. I think its brilliant

 

@Fern4

Yes, nice design and have decided to include a water feature next to it.
Attached a sketch of the proposed change to the garden bench.

@clueless1

Yes, good idea to work out everything before hand, nothing worse than having to dig something up because the electrical cable was forgotten about.

For lighting, I'm thinking about the ground mount LED types (would have to cut into the concrete though) and then place pebbles around them.
Will also add some solar lights.

As to the plants, I will leave that to the "boss" as what I know about gardening is less than nothing.

EDIT:

Any suggestions as to ferns/plants/flowers that would cope with the conditions I wrote about previously?

 

Not if you're still going for the raised idea

 

Haa good point clueless1, the wiring can be run in some PVC pipe and then buried under sand, pebbles or what ever.

 

Just make sure you use a Residual Current Detector (RCD) with outdoor electrics. It's just to make sure nobody gets electrocuted in the event that the cable is damaged or exposed to water. Might also be worth checking what regulations apply in your part of the world.