Rick wrote:
Hi,

I laid land drains in my garden this Summer and despite packing the
topsoil down on top of the stone now find the soil has sunk slightly.

Can I just sprinkle topsoil on top of the new grass NOW that has grown
(from seed) and expect it to come through next year?

How badly sunk is it? You can usually add a 1" top dressing of sharp
sand & loam selectively to hide low spots and get away with it. I'm
doing that on my lawn now.

You might get away with a 2" top dressing, but it depends how long the
grass is.

What methods should I use to encourage early growth for next year.

The other way involves turf cutting, filling underneath and much
stamping & cursing. Even if it takes a couple of years to get a perfect
flat lawn I prefer selective top dressing. YMMV

Regards,
Martin Brown