For most, the safest fertiliser would be one of the brand names on
sale at your garden centre or supplier. It stands to reason that the big
brands have much experience in providing as fail-safe as possible, a
product for turning your grass green without too many hiccups unless
you ignore their instructions!
Most established and cared-for lawns will only need a dedicated feed
rather than a combined feed, weed and moss-kill variation. If you do
not have weeds, or moss, there is nothing to be gained by trying to kill
them! On the contrary, it can be argued quite forcibly that you are just
throwing chemical at the environment.
If you have a weed problem
that cannot be sorted by spot treatment, then a combined fertiliser
weed-kill is the route to go. You may have no option, for many garden
centres seem to major on stocking the 3 in 1 version!
If your lawn has been invaded by moss often visible after the first
cut or so, then you can uses a combined feed and moss application. The
moss application is a short term measure you need to do something
about the root cause of moss in lawns.
If you only want feed and want a dig at the garden centre then
use cheaper and environmental-friendly chicken pellets!
There are chemicals other than dedicated lawn fertilisers that can
be used. Here we talk about reliability and tried and tested methods!