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Growing Azaleas and Rhododendrons


For years I have tried to grow Azaleas and Rhododendrons with limited success. Often in the winter the leaves will turn brown, roll up and next spring after they bloom, they seem to have fewer leaves. So it becomes a slow, steady decline unto death.

I've been told that I probably need to add fertilizer and lime in the fall. But I was also told by others not to fertilize until after they get done blooming in the spring. What am I doing wrong?

Answer

Azaleas and Rhododendrons require acidic soil conditions with a pH of 4.5-6. I would therefore recommend against the use of lime as this will raise the pH of your soils, making it more alkaline. Depending on the quality of your soil your plants may or may not require any fertilizer. If you regularly add compost, leaf mulch or any other organic amendments to your soil; there is no need for any additional fertilizer. Azaleas and Rhododendrons thrive in loose, loamy soils that are rich in organic matter, and make excellent use of the slow release of nutrients from the natural decomposition process. It is therefore more advisable to periodically amend your soil rather than merely supplying a synthetic fertilizer; or make use of organic fertilizers as these too are slow release. When selecting a suitable fertilizer be sure to look for something labeled for 'acid-loving' plants, as this will ensure you retain a low pH for your plants. Early spring, before or after flowering are good times to fertilize, or alternatively as plants are going dormant in autumn. Avoid fertilizing from mid-summer to early autumn as this will encourage new growth that might not fully harden. Be sure to use any fertilizer sparingly as Azaleas and Rhododendrons have sensitive roots that can suffer root burn easily.

Be aware that Azaleas and Rhododendrons prefer damp summers and have shallow root systems, thereby making them susceptible to droughts. Be sure to provide supplemental water during hot and dry summers. Ensuring your plants are in a suitable location will help lessen any future problems. Select a shady or semi-shady location with a rich, damp and well-drained soil that is somewhat wind sheltered. The curling of the leaves you are describing sounds like it could be winter injury. Winter injury has various causes but many times it is due to either moisture loss or late/excessive fertilization. Be sure plants go into winter well hydrated, so water plants if necessary, and mulch the area around them. If they are in an exposed area provide some protection from drying winds. Avoid late or excessive fertilizer applications.



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