"sarah" wrote in message
. ..
: I've got summer broccoli, miniature kohlrabi[1] and miniature Savoys,
: all of which are showing mottled yellow patches on some leaves on some
: plants. The patches bear no apparent relationship to water droplets or
: anything else, and the affected plants have an indefinable air of being
: under the weather. Could this be a virus, or is it some deficiency I
: could do something about? Watering with dilute seaweed extract didn't
: significantly cheer them up.

Are you sure they don't have cabbage root fly or club root disease? If they
are like that and all 'floppy' I would say it's either one of those