Posted: 27/04/2014 at 21:01
Yellow rattle needs to be sown in autumn. It never fails for me. It's been sowing itself for years now.
Other reliable ones are lesser knapweed, Centaurea nigra.
musk mallow, Malva moschata.
Meadow geranium, G. pratensis
and various vetches and vetchlings, some of which are annual but seed from year to year
Field scabious to a lesser extent, it's there but doesn't increase much