In article , Jan
writes

Thanks, Jane. You say that spiking should be done in autumn? My lawn is in
a sorry state, inherited it 3 years ago and not done a thing with it since.
So, can I spike it this spring?

Wait until the grass is growing strongly or you are likely to do more
damage than good. I don't know where you are in the country, but, here
in Lancaster, we seldom do anything, other than give it a long haircut,
before mid April and often not until the beginning of May.

I'm all gung-ho; armed with moss killer,
weed killer, fertiliser, horticultural grit, new scarifier and new spiker.
I'll be most upset if I can't use my tools until autumn!

The supposed 'correct' technique is:
1 in spring when grass starts to grow strongly, give it a haircut
using a high lawn mover setting. Too low a setting will set
back the early growth
2 do your weed/feed/mosskill stuff, complying with the weather
conditions specified on the packet (and that is hard enough
to do as it is )
3 do the scarifying bit a few weeks after the weed/feed/mosskill
exercise (if your lawn is really bad then you will end up with
something with bald patches at this stage - we just let them
fill in naturally but some people go to the trouble of
applying grass seed - but this, then, gives you a problem with
subsequent mowing as new grass can't be mowed the same as old
grass as it is not tough enough)
4 mow at least once a week through the growing season
5 scarify once every 4-6 weeks depending upon summer weather
conditions (some weed/feed/mosskill treatments
recommend a second application at some stage)
6 in autumn (we usually do it in September but have done it in
early October depending upon the autumn weather conditions)
spike the lawn
7 After spiking, apply top dressing (at which time
you can level off any dents with top dressing) which includes
sharp sand/peat/loam to supply drainage and nutrients to the
soil at the grass roots
8 repeat from 1 next spring!

After repeating the above sequence for a few years you will find your
lawn improving dramatically. Even so, after a wet winter spell like we
have had this year, the moss will come back unless your lawn is *very*
well draining . . . . but if it is very well draining, it is likely to
die back and go brown in a dry summer . . . sigh we just can't win
with lawns in this country (((((((((((

Having said that, I suppose there is no reason not to spike your lawn
this spring. It's just that it is usual to apply the top dressing after
the spiking so that the top dressing can fall into the holes over the
winter whereas if you apply it in the spring you will mow/scarify it all
back up!!!!!!!!!
--
Jane Ransom in Lancaster.
I won't respond to private emails that are on topic for urg
but if you need to email me for any other reason, put ransoms
at jandg dot demon dot co dot uk where you see