How do I improve the soil in a well planted garden?

[Kitsmummy]

The soil is fairly rubbish, I should have done this before planting but I didnt and I'm regretting it now! I can't really dig stuff in because Of all the plants/roots being in the way, so is there something I can just leave on top of the soil and, if so, what? Thanks

Compost
Sharp sand if it's clay

Cardboard soaked and compost on top helps too

The worms will get it all down eventually :) layer compost on top as a mulch each year and it'll work its way into the soil

Mulch! Just dump loads of cheap compost on top of the soil, and let the worms do the work for you.

It looks really, really lovely by the way - so green and leafy. Are you in the UK?

Thanks so much, plain old compost it is then. And yes to the UK...I'm in rural Somerset...all those mountainous trees you can see in the background are actually the edge of a quarry!

You can just put manure on top as well (well rotted) and the worms will drag it in over the winter.

Wow, you must get some amazing birds in your garden with all those beautiful trees. It looks incredible, and I did wonder for a second whether you were somewhere far flung and hilly!!