On 10 Mar, 17:46, Ted wrote:
* My new allotment is quite water retentive..I am thinking of putting a
few raspberries in and wonder if I dug the trench deep enough then put
in about 6 inches of quarry waste (limestone) it would help the drainage
by routing it off my plot...Will the limestone affect the Raspberries ?
--
Regards
* Ted Wager
* *High Peak UK
* * Using Ubuntu Jaunty Linux

I had just this problem in my plot and solved it by building a (very)
deep raised bed. Edged with 2ft sq concrete slabs on edge and sunken
about 9" into the ground. Filled with good soil, grit and well rotted
fym having broken up the bottom as best I could. Overfill and mound it
up because it will settle.
Rasperries need a well drained, open, slightly acid soil so forget the
limestone. Depending on the nature of the soil you use, you can use
non-limestone pea gravel or horticultural grit for the gritty
component. They've been in just over a year now, made excellent growth
and will give a heavy crop of good quality fruit this year.
Your proposal would simply turn into a water retaining sump I'm
afraid, by all means do something like that on the upslope side of
your fruit bed to catch the water and send it elsewhere (that's a sort
of 'French Drain').