In article , Phil L
writes
Interesting link Alan...can nettles be composted like this at any time? -
what about the heavy seed heads which appear from time to time? - will the
seeds rot too? -

All parts of nettle plants will compost at any time, but for making
infusion it is better to use tender tops without seed-heads as they bio-
degrade more quickly and do not produce a fibrous mush at the bottom of
the vessel.

I have inherited an unused greenhouse which has been taken
over by nettles and has been like this for about 5 years, I've a feeling the
soil will be rich in nutrients and I'm planning on getting all the tops out
in a few weeks, then digging the roots out.

Yes, do that. You will find that the nettle roots will have already
performed part of the soil cultivation for you - one of the lesser known
benefits available from these versatile plants. Be sure to compost the
discarded nettle material, or you could cut it all up and dig it in
where it is to rot down, any self-sets appearing later would be easy
enough to remove when they are small and are unlikely to re-grow.

Another question: will the roots compost in this way or am I better burning
them?

Yes, roots will compost, but they will take a little more time to do
that than leaves and soft stems. If you have a lot of them and a
shredder, it would be worth running them through that first before
composting.

I'm planning on tomatoes, chillis and courgettes, planted directly into the
soil...

Those will all benefit from the residual nutrients left from years of
nettle growth in the soil. Depending on your region and on your plant
management, you may find it better to grow the courgettes outside in a
sheltered position. In a greenhouse, they can tend to be all foliage and
very few fruits - but it varies.

In future seasons, remember for the purposes of plant rotation that
tomatoes and chillies [and potatoes] are in the Solanum family and are
susceptible to blight if using soil previously occupied by that family.
We alternate them with melons, green beans, salad greens, cucumbers etc.
--
Alan & Joan Gould - North Lincs.