Hey GardenFaerie, you probably already know, but if you can find some ladybirds/ladybugs (dunno what you call them over there) they love spider mites and aphids, I mean love to eat...One ladybug can consume 1000 aphids in 24 hours! I'd encourage any grower to find where and when the ladybugs inhabit your area, and keep it in mind just in case of. Your neighbours' rose garden is a damn fine place to start!
I like the fact you using something natural for your insect problem though...
Can I ask everyone as i don't know, are there any implications for foliar spraying of the potassium on GardenFaerie's plants....the brown colouring and lack of growth....It's just a thought Garden, and I don't know, imagine you've already looked at it...I dunno anything, but just an observation based on what you said...trying unsuccessfully to be helpful!