New turf turning brown/black

Hi
I'm new to this forum and to gardening altogether so really hoping you can give me some help and advice and apologies in advance if I'm not giving enough or the right information.
At the start of June, we had a hedge taken away and a fence put in around the perimeter of our garden. Unfortunately, the digger that was used destroyed our grass and so we had no choice but to lift what was left and replace with new turf.
Being complete gardening novices, we followed the instructions from the turf company and various online resources religiously. We spent days preparing the soil with a rotavator, rolled it, put down top soil and laid the turf as soon as it arrived. We spent a bit more on the turf than we had to - we bought "elite" turf - and we watered it every day throughout the summer using a sprinkler, even putting down containers to make sure we were hitting the minimum amount of moisture each day. We used a grass fertiliser once after about a month.
Three months on and the turf looks great if we don't cut it. If we leave it to grow to about 4 or 5 inches, it looks really well - a lovely dark green colour and what looks like really healthy grass. Unfortunately, our garden then also looks like a field!
When we mow it, it looks terrible. It's mainly brown or black but doesn't seem to be dry - in fact, it's almost boggy in places. It is also a nightmare to mow. It clogs up the mower and it takes three times as long to mow as our old lawn. We aren't even able to get it very short because it seems to be in such bad condition. As I said, if we leave it to grown for a few weeks, it will look great again (but far too long).
I've attached some photographs (please ignore the leaves in the last photo - didn't have time to clear them this morning - they're not normally there!). If anyone can give us any advice on what we should/should not do I'd be really grateful.
If you need any other information, please let me know.
Thanks!

 

Welcome to Gardeners Corner

Not a lawn bloke myself, but someone will be along soon

 

Thanks so much for the advice. My husband has decided it's definitely the lawn mower and is using it as an excuse to say we need a new one!
The fertiliser was Evergreen stuff that attached to the hose and sprayed. I used about half which was right for the amount of grass we have but the black does sound like it may have been caused by that. I take it it will just revive in it's own time if that's the case?
We certainly didn't have any problems with the grass being too wet before so can't understand why we're having so many problems now but your explanation would certainly make sense.
Really appreciate you taking the time to reply.
Thanks!

 

Welcome to GC Claire. It looks like water logging to me and I would never put fertiliser down on a first year lawn, it needs to establish roots first and the fertiliser is to strong while it is still so young. New grass will find enough nutrients in the soil to see it through it's first year.

What type of soil was underneath the topsoil you laid, clay, sandy etc.? If your soil was clay it's usually advisable to dig in some grit or sand and then lay sand before turfing. If the soil is sandy then it's best to dig in compost or topsoil and finishing with a layer of topsoil.