My second year cascade is growing like crazy, at least two feet tall, and growing fast. But I've noticed the edges of the lower leaves are Browning. Is this a nutrient issue, or something worse?
Thanks for the help.
Could be an early infection of some type. I'd take a couple of leaves to my local garden center and ask what they thought.
Usually a nutrient imbalance, possible nitrogen burn or deficiency. Any of the major N,P,K, macronutrients as well as S,C, or Mg can cause this. Very hard to nail down plant issues visually. Good luck though.