09/28/2026
Purple tomato leaves in cool weather usually mean the plant can't reach the phosphorus that's already in the soil. Cold slows the roots, so the nutrient is there but locked out.
That's the case feeding at the roots solves. MARPHYL Phosphate, watered in at 1:20 every 2 weeks, puts phosphorus where the roots are already working, so a cold-slowed plant isn't left waiting on the weather.
Watch the test: if the new growth comes through green while only the old leaves stay purple, the roots are catching up.
Sources:
- University of Maryland Extension - https://extension.umd.edu/resource/key-common-problems-tomatoes