Why we can't plant very close to patios, or drive edges

A Client asked me, recently, why they couldn't get any plants to grow at the very edge of their recently re-laid patio: they wanted to "soften the hard edges with planting" (as recommended in gardening books and internet articles) to make it look the way it did before it was re-laid.

This - left - is the sort of effect they were looking to recreate: where the plants grow right up to the edges of the patio.

They had tried putting in plants, right at the very edge of the patio slabs, just as they had done in the past - but they'd all died. 

The problem lies in the way patios are laid, these days: in the old days, patios used to be properly built: having prepared the foundation, builders used to construct a "form" of wood, around the area: they would then lay each slab separately, on blobs of concrete, taking care that they were all level and flush with each other: once it was all set, they would remove the wooden form, fill the gaps with pea shingle, and replace the soil, right up to the edge of the patio.

This meant that planting was possible, right up to the patio.  Edges were softened. Clients were happy.

But that required skill. 

These days, they just spread a layer of concrete, and lay all the slabs at once, mortaring in between the joins. This is much easier and quicker to lay, it makes a very solid patio (right up until the time the joints start to crack, of course!) with no weedy joints. 

But the problem, from our point of view of wanting to add plants around it, is that they have to build a ramp of concrete, flaring out from the "loose" edges of the patio, ie any edges which are not butting up to a wall, house, or garage.

Like this:

Can you see the "ramp" of concrete?  

It projects out, all the way round this small patio, including going under the grass, and extends several inches further underground.  

It makes a good solid patio, and once the soil is replaced, and smoothed back level with the slabs, it looks lovely: but it clearly shows why we can't plant right up to the edge.

By the way, don't even get me started on the lack of a straight edge at the back here: as far as the builders were concerned, this edge was "out of sight" and therefore didn't matter. Ah, I do love people who take pride in their work, don't you? 

To be fair, the front edge did look very nice.

Drives, incidentally, are the same: the edging setts have a big ramp of concrete extending under the lawn, or into the bed.

For the lawn, it really doesn't matter, as grass will grow over stone, brick, concrete....

 

As I mentioned in a post last February, about replacing a poor-quality lawn:

... this - left -  was an area of apparently perfectly healthy lawn, been there for years, but it turned out that the patio to the left, extended all the way underneath it. 

You can see how I've rolled back the turf like a, well, like a roll of turf!

The grass was happily growing, and had been for many years, with barely an inch (3cm) of root-filled soil. 

So we don't need to worry too much about the grass.

But plants are a different story, partly because they need their roots to be in a decent depth of soil, and partly because concrete has a very high pH, between 12-13, which is pretty much as high as the scale will go.

Reminder: "normal" pH is around 7.  An "acid" soil will have a pH of maybe 4-5, and will be suitable for acid loving plants such as rhododendrons, camellias, pieris etc, and will turn your hydrangea flowers blue. An "alkaline" soil will have a pH or maybe 8-9, and quite a few of the edible plants, vegetables etc, are quite happy with a slightly alkaline soil. But 12-13? Pfff! Way, way too alkaline!

The only answer is to choose spreading plants, so that you can plant them a foot or so away from the new patio, and just allow them to spread gradually. Forget this instant gardening! Be patient! *laughs* They will get there, in time, and you will forget that you even had a problem with the area.

And that, dear reader, is why we can't plant close to a patio or drive...

Did you enjoy this article? Did you find it useful? Would you like me to answer your own, personal, gardening question? Become a Patron - just click here - and support me! Or use the Donate button for a one-off donation. If just 10% of my visitors gave me a pound a month, I'd be able to spend a lot more time answering all the questions!!