[mrs bouquet]

Operator error I think.   I used my scarifying machine on the grass.  Then raked it with a spring rake. So much rubbish came away.   Then I cut sticks to make 1 square yard, and weighed out preparation, then sprinkled it on by hand.    The next day it rained.   It looks terrible,   in some places the actual grass has gone black, and elsewhere there are large patches of just dry grass, and a few bare patches.Over-kill, I am guessing - but what do I do next, leave it, rake it again, mow it, feed it - I just don't know because this has never happened before.   Advice please.    Mrs Bouquet

[Gardener and Rabbit]

It does look a mess after scarifying, that's quite normal. The blackening of the grass will be from iron sulphate as a mosskiller in the Weed, Feed and Mosskiller.  I'd leave it a couple of weeks now, and see how it regrows. At this time of year it should grow back strongly and recover well. I wouldn't apply anymore fertilizer, since you've already fed it. 

Any bare patches and thin patches will need re-seeding. If the scarifier has left grooves in the soil, try to work the grass seed into those.  G&R