Yellow Leaves on Double Knock Out Roses in Extreme Heat

Problem

Forty red Double Knock Out roses planted at a church show yellowing on plants in full sun after 4–5 months. Some may have dried out temporarily. The gardener asks whether to fertilize or wait.

Explanation and Advice

Yellow leaves indicate heat stress, not disease. Newly transplanted roses often suffer root shock in summer heat. They will not die even if they drop all leaves—roses can regrow foliage three times without harm. Do not fertilize in high heat; chemicals burn roots. Keep soil consistently moist (not wet) and wait for cooler weather. New, healthy growth will resume naturally.