Rick Stevens wrote:
Hi
I planted a Melanthus major in the early part of the year when it was about
2 feet high. Its gone absolutely crackers this year and now stands approx 7
feet high with 4 very large flowers.
I have 2 questions really:
1. Does this plant need pruning/cutting back? If so, when should I do it
and how far do I cut it back?

In early spring cut back the stem from 2 or 3 buds from the base.

2.After a particularly hard frost last night, It is looking decidedly sorry
for itself, all the leaves are limp as are some of the flowers, Will the
frost have damaged it, or is it just sulking?

You need a dry mulch in winter, braken, straw ... It's perhaps got
cold, but it's not all lost. Make sure you keep the base snug.