In article ,
Andy Parker wrote:
I have a project to plant up a "border" 70 metres long and about a metre
wide in an area of a public park that our Society lease. It faces East or
ENE and is backed by a 3 foot retaining wall and railings above that.
Soil is due to be tipped there shortly but it looks more like clay to me.
Ideally the border will be at least partially evergreen, under 3 metres
tall, low maintenance and look OK next July when we have a big anniversary
event.

Bluntly, you will need to sow annuals - nothing else will establish by
next July. For the slightly longer term, consider Aubretia for ground
cover (to be overgrown as shrubs mature). I don't have experience of
clay in Cumbria, and the plants that grow well we me (sand in Cambridge)
will not do with you.


Regards,
Nick Maclaren.