Rhododendrons

Dec 4, 2023 | Gardening Advice

All of the over 4,000 species and hybrids of Rhododendron (ro-do-DEN-dron) grown in America need the right conditions to thrive. A cool, moist climate, with plenty of atmospheric moisture, and acidic soil, with ample moisture, will ensure a robust plant. Due to these necessary conditions there are areas, such as the central U.S., where they will not do well.

PRIME LOCATION: Rhododendron are extremely long-lived; plant them where they are to remain. Place in a location with protection from the summer sun, winter sun, and winter wind. Do not plant where ice and snow can fall on the plants and damage branches. (When the plant is small protective “sandwich boards” work, but become more cumbersome as the plant grows.) These plants will not tolerate compacted soils on their roots, so provide a path. Take care in planting that the surface roots are not damaged. Rhododendron are rated **** in deer restaurant guides.

SUN: Sun or light shade in summer; shade in winter. They should not be exposed to long periods of hot summer sun.

SOIL: Rich, acid (pH 4.5-6.5), well-drained, light soil. Do not apply lime. The feeder roots of the Rhododendron are very close to the surface, so you do not want a soil that will dry out in heat and drought. The soil should have high amounts of organic matter, not only for nourishment, but to retain moisture. If planted near a foundation pay close attention to the pH; water splashing on the cement will tend to make the soil alkaline. FERTILIZING: An acidic fertilizer, like Miracid, should be applied in spring and early summer. Stop fertilizing in mid-July. Water with 1” of water weekly for the best bloom. MULCH: Much appreciated. An organic, non-packing mulch will keep the roots cool as well as keep the soil acidic. Do not apply more than 2” deep. PRUNING & DEADHEADING: After bloom carefully remove the flower heads just above the new leaf shoots. This will direct the plants energy into next year’s bloom. If necessary prune only in the very early spring. Be sure only to cut back to a bud or small shoot. Rhododendron will not produce new buds. Old wood should be removed both for appearance and to allow light into the center of the bush.

DISEASES: The best protection against Rhododendron diseases is to provide proper growing conditions.

WINTER CARE: Do not let them go into winter in dry soil. A burlap screen should be erected around the plant, on four sides, to prevent leaf desiccation. It is also advantageous to spray with an antidesicant in November. A product, such as “Wilt Proof” or “Cloud Cover”, may be applied according to package directions.

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RHODODENDRONS

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