Catnip concern, maybe a nutrient problem?

[ValC2016]

I'm a novice(but highly addicted) gardner, finally decided to register for an account here to hopefully gain a better understanding of my first and strongest plant. It's a small catnip bush that is doing great, only better the more I prune. I posted this to ask about a strange characteristic I've noticed since roughly a month ago, when the leaves of my plant started developing yellowish marks on it. The pictures show it just fine. They are slightly translucent, even slightly sparkling, and seem to be spreading slowly, at least on the leaves that are affected. This ranges from brand new young leaves, to the oldest and biggest, skipping plenty in between. It's definitely not thirsty, and still thriving with many new shoots every day. I obtained a fish emulsion fertilizer and have used it twice over a couple weeks, it seemed to make it happier, but the strange marks continue, even on some of the new leaves. Plenty of sun, I don't leave it out all night (Oregon nights in zone 6), it sometimes has bugs on it, but nothing remarkable or severe at all. Is there a key nutrient I'm missing that would cause this? Is it nutrient related at all? I'm pruning it daily, to some degree, and it seems to only do better the more I keep it up, yet still the pattern continues. Please give any feedback you have, any and all is appreciated!

In my history, I've been a black thumb as long as I could remember. I finally understand the needs of plants better and I'm very proud to posses a plant that makes these efforts worth it. I'd love to save it if needed, and cater to its needs more, if not. 

This shows the leaves, bear in mind I battled the bugs with some DE, so not all the white areas on the leaves are indicative of the condition I specified. Some of them look troublesome but they are intentional. Also, purple stems? Is this normal? If not how can I adjust?

 

[rz3300]

Well I really cannot say, but I am a little disappointed in myself for not realizing that I could grow my own catnip. It does make me worry a bit about what my little friend might do should I not be around, though. To be honest I never really thought about, and so I am sorry that I cannot help you with the purple stems or anything, but thank you for introducing this to me. Might just have to add it to the list...thanks again for sharing.

 

[kgord]

i have seen catnip seeds I think, but I have never really tried to grow them. My cat does like a bit of the "nip" from time to time. I should try to grow some, maybe indoor on a window sill because the growing season here is about over now. I should look for the seeds someplace. However, I have terrible luck with seeds as a rule.