Clematis leaf edges yellowing
I have two clematis I planted last fall. They are very close to each other and have received basically the same care, light, etc.
On one of them, the edges of some of the leaves started to yellow (see picture). The other one seems fine but there are some hints that it might be yellowing.
I think this looks like potassium deficiency, but I'm open to other suggestions.
I haven't fertilized it frequently. At planting, last fall, in the spring and again recently when I noticed the yellowing.
I use this little plastic scoop to measure out the fertilizer. I thought it was a 2 oz scoop but it turns out it's a 1oz scoop. (DOH!) so it didn't get as much fertilizer as I thought.
Is it ok to fertilize this time of year? There are no blooms right now but I think that's normal? Should be coming soon though from what I remember of last year.
I usually use Espoma Garden-Tone (3-4-4), but I also have a Tomato-Tone (3-4-6) which is higher in K which might help if it is potassium deficiency.
If you have any recommendations it would really help me if you also could let me know how many days it might take to see a difference.