"H Ryder" wrote
My soil is compacted clay, with hardly any worms. Have decided to try
double
digging the borders. Is this a good idea? What should I dig in - I've got
some sharp sand and compost. Will this do - I can't really afford grit .
Would appreciate any advice

Also what is the best technique for actually breaking up the great, hard
lumps. Hitting them with a spade just seems to make them harder! TIA,
Hayley

We garden on Thames silt/clay and I understand your problem exactly. I once
earthed up my spuds by building a dry stone wall with the lumps! ( I can
:-) now but I didn't at the time)
Yes, try to dig it if only to get some air into the soil and incorporate
your compost/sand. The worms will come idc once there is some air and food
in the soil. I use a fork to break up the lumps but it is best to wait until
the soil is easier to till. It needs to be damp but not wet, dry and it's
impossible, it's a case of catching it at the right time.
Gypsum (from builders merchants) spread on the soil after you have dug your
best will break up clay for a number of years, enough time for you to get
lots of organic material (and sand) incorporated. Lime also works to make
the soil friable but only for a short while, a season at best.
You need to try to keep off the soil once dug so as not to compact it again.
raised beds are a good idea, or at least beds so you can garden on from the
paths.

--
Regards
Bob
In Runnymede, 17 miles West of London