DaveDay34 wrote in message
...

Snip

You do better than that in winter (but the sun is weak) and worse in
summer. You also potentially lose some protection from wind too.

Maximum altitude of the sun is at transit due south (approx 1pm BST)
Summer 90 - latitude + 23.5 ~60 degrees
Equinoxes 90 - latitude ~37.5
Winter 90 - latitude - 23.5 ~14

(Assuming a latitude of middle England say 53.5 degrees)

So the gain in illuminated ground at midday as a proportion of hedge
lopped off is roughly 58% in midsummer, 130% at the equinoxes and 400%
mid winter (although the sun then is so feeble as to be useless). The
overall influence is about half to two thirds of these values in
practice since the sun isn't permanently due south or at its maximum
altitude.

NB You can always lop the N side with a chamfer to allow more light in
but without chopping as much off the overall height.

Regards,
--
Martin Brown





Sorry, but this is becoming too much like a maths lesson and not enough
like an
exercise in improving the light levels on your allotment for my liking. I
know
I run the risk of upsetting you (and several other people) but why don't
you
stop messing about and just go and cut the bloody hedge down to a more
reasonable height?

Sometimes less (talk) is more (action).

Dave.


Dave, I have lol! Well about a quarter of it. The reason I asked the
question in the first place was because I could tell it would not be an easy
job (and I was right). I guess I could have gone into "action" immediately
and see for myself, but finding out first was very helpful in getting myself
towards the "action" bit. The hedge incidentally is 13 foot high and I've
managed to get rid of 5 foot with a hedge trimmer and secateurs, the rest is
too compacted (it's privet) and I think I'd need a chain saw to slice it off
or something, so it will have to stay at its new 8 foot height.