Janet Tweedy wrote:

Now I've managed to build nearly all 12 raised beds at the top of my
garden (a scaffolding plank long and 4 foot wide) I would like to cover
at least part of one or two to start early crops.

Can anyone with more experience of growing vegetables this way suggest
the best/most efficient means of warming the soil and/or growing under
plastic/fleece?

Janet
I bought round plastic electric conduit and plastic water pipe. Cut two
lengths of conduit then push into each end of a length of piping. Push
the free ends of the conduit into the ground and you now have an
inverted U shaped frame astride your bed. Cut the pipe and conduit in
lengths to suit your requirements. Repeat this for the other end of the
bed, and in the middle if they are long. This works well, I have been
using mine for several years and covering them with polythene, fleece or
netting as required. To anchor the end I screwed stable bolts (Wood
screw one end threaded bolt the other)into the tops of the planks and
used these to secure wood strips to hold the cover down on the sides and
ends of the beds. I bought mine from screwfix, well worth it if you are
going to make a number