Wednesday, 28 May 2014

The perfect lawn - more complicated than you might think.


This garden in the west of Scotland was built on a piece of moorland in the 1960s and no attempt was made to add drainage infrastructure to the ground before the building project began.

For about 20 years the owners followed the instructions of gardening gurus and treated the lawn with moss killer and weed killer and and so on. However, the ground is extremely wet, and I don't think that the manufacturers ever really intended the chemicals to have a miraculous effect on such ground. The work has been an interesting experiment to show how the population of plants responded to the treatment.

As it happened, the owners treated only part of the lawn, while another part was untreated. Strangely, in the treated region the edges were also missed, so that we can now compare the effects on the two areas. Both areas still have a great diversity of species, but the ranges of species in the two areas are very different. This difference may also be to do with other variables, as the two areas are on different sides of a house, and have different drainage. The treated lawn is surrounded by a six foot tall hedge, while the untreated lawn has a 30 foot tall woodland on one side and a steep drop on the another side.

This photo shows the edge of the treated lawn. The untreated edge has a lot of green grass and daisies, while the treated area is mostly moss and grass.


This is a close up of the untreated edge. Most of the species are broad leaved, and the majority of obvious plants are grass and daisies. 


This is a close-up of the treated area. It contains very sparse grass and a lot of moss (I like moss, so that's not a complaint). 


In the completely untreated area on the other side of the house there are also a lot of broad leaved plants, and a lot of grass. This photo below shows a common marsh orchid that has seeded from nearby.



There are a number of interesting wildflowers. I like this one, but I have not had a chance to identify it yet. 


There are a lot of buttercups. 


There are quite a number of reeds in one very damp area. I like the reeds and the general diversity of species. It gives information about the soil conditions and I like watching the soil conditions change over the years and seeing that change reflected in the population and growth of the plants on the surface. 


Returning to the treated area on the other side of the house, we can see that this area also has a great diversity of species, but here the species are mostly mosses and just a few grass plants here and there. 

It's very hard to say what the connection is between the years of lawn treatment and the presence of the moss. Was the lawn treated because there was a lot of moss (and that moss is still there in spite of the treatment)? Or is the moss there because of the effects of the lawn treatment (removing broad leaved weeds that might have removed some of the water from the soil and reduced the tendency for moss to colonize the area.) I don't really know what the reason is for the large quantity of moss. However the area is notable for its lack of daisies and I assume that that is to do with the long term application of weedkiller. 

 This is a photo of a representative section of the treated lawn.
 It has a lot of interesting mosses and not much grass. 


This is a particularly attractive moss in the treated lawn. 


There are also some lichens. 


Another lichen:



So what is the conclusion here?

To reiterate, this is about making a lawn on undrained moorland, which is a pretty interesting thing to try to do.

It seems to me that the weedkillers were very effective at getting rid of daisies, but I quite like daisies, so on balance I'd be inclined to just keep them and no bother to use weedkiller. That's a personal preference.

From the moss point of view, I suspect that it's all down to the drainage of the site. The treated lawn seems to me to be much less well drained than the untreated part of the lawn, so it's entirely possible that the moss situation seen here is purely related to drainage, and unconnected to the use of moss killer over the years.

I could be wrong about that though, and it may be that the removal of the broad leaved weeds has made the ground even wetter and that the ground has become a bit poisoned by heavy use of chemicals.  I suspect that the health of the grass has been affected by the use of lawn treatment, because the grass actually got more and more sparse with more treatment. Perhaps the nitrogen fixing weeds were lost and that made the ground less attractive to grass and more attractive to moss. Possibly in such we ground it would have been more effective to just apply a nitrogen feed to encourage the grass and help it to out-compete the other species.

What's my main conclusion though?

Well my real conclusion is that if I found that I had a mossy lawn then I would try to become interested in mosses and enjoy it. If I had a lawn full of wild flowers then I'd try to become interested in wild flowers and enjoy that. If I absolutely had to have a perfect lawn, and I lived in a very wet place, then I think I'd grow it in a pot.