Posted: 13/07/2015 at 19:56
Hi kat - I can sympathise enormously. Is the 'slimy' area constantly wet? I can only guess, but it sounds like that part hasn't been improved well enough and is acting like a 'sump' for all the water. You may have to dig that part out to a good depth and replace with decent soil/compost and grit to aid drainage. The stones coming to the surface may have come from the soil that's been put in to replace your sticky clay. If they're small it won't really cause a problem. Trying to get a good lawn from the type of area you describe will always be difficult - the water table in your area could be the issue.
In general, for lawns which have poor drainage, and therefore poor quality grass, you need to spike regularly and brush grit or sand down the holes. In the worst cases, you can use a tool with hollow tines which remove a long plug of soil and that's replaced by coarse grit.