Or are you asking about Brussels sprouts?

?

purple sprouting is what I meant and seem to recall having it by now previous years!
Lower leaves are falling off, maybe climate change!

Feb/March for purple sprouting though have to confess we never had any success with!

If the plants are now tall its normal for lower leaves to fall. doesn't look as though you have anything t worry about. I've never had them sprout in the autumn - but there are some varieties that will so perhaps you had an earlier sort last time you grew them.