It does sound like a deficiency. The three elemental deficiencies that can cause purple/bronze foliage are N (only in some plants. All plants won't display purple foliage if N is deficient), P, and Mg.

Your zone or where you live would have been helpful, because temperatures can play heavily into the problem, especially when using organic sources of nutrients.

I would hold off on the fish emulsion, at least temporarily and fertilize with any 3:1:2 ratio soluble fertilizer. MG 24-8-16 or 12-4-8 are examples, along with Foliage-Pro 9-3-6 (very good choice).

Other cultural influences that slow growth w/o slowing photosynthesis will also cause a build-up of anthocyanin (purple pigment) in foliage, so it could be something she's doing (over-watering, e.g.).

Thanks Al. She is in Zone 5 in Maine - so it has been cold up there, as well as almost two months of rain. So I expect the "overwatering" by nature as well as all of the nutrients washing away on a regular basis are both contributing factors. Luckily, Foliage Pro is easily available in Maine (i can't find it here in Virginia and ended up ordering it online). Thanks again!