Azaleas and Rhododendrons: Planting
Selecting the Site
Rhododendrons grow best when planted in acid, soils with a pH of 4.0 to 6.0. The soil can be made more acid by adding ferrous sulfate or copperas, iron chelate, or finely ground dusting sulfur. Adding liberal amounts of peat moss and decaying oak leaves also tend to make the soil more acid.
A loose soil rich in well-composted organic matter is ideal, and good drainage is a must. If drainage is a problem, a raised bed 8 to 12 inches above ground level is recommended.
During hot periods, flowers will last longer on plants in filtered shade than on those in full sun. Partial shade also helps to reduce cold injuries in winter. Rhododendrons planted under shallow-rooted trees, such as elms and maples, suffer from competition for water and nutrients.
- Dig the planting hole two times wider than the root ball and the same depth. Wider planting holes encourage the roots to grow into the native soil so that the plant will establish itself quicker.
- Place the plant so that the top of the root ball is level with the soil surface, then backfill with native soil removed from the hole. As you replace the soil, break up heavy clods and remove stones and debris.
- Do not fertilize the plants now. Wait until they are established.
- Apply three to five inches of mulch around the plants. This final step is very important to help conserve moisture, moderate soil temperature, and prevent weeds which compete with the plants for nutrients and moisture. Organic mulches including pine straw or bark are excellent mulches. Wood shavings, chips or sawdust can be used but will result in loss of nitrogen. Fall leaves are also a good mulch.