Azaleas belong to the Rhododendron genus. They can be distinguished from real rhododendrons by their smaller, dark green leaves and tubular flowers. The shrubs are also smaller and wide branching.
There are many types of rhododendrons. They range from low-growing dwarf azaleas to huge evergreen shrubs that can grow very high. Rhododendrons vary in size from 15 cm to 10 m and everything in between.
Most rhododendrons really require acidic soil (pH levels from 4.5 to 5.6). Otherwise they do not grow any flowers. Fortunately, you can take the necessary precautions when planting your rhododendrons to ensure your plant will be absolutely fine for the first 20 years.
Rhododendrons are acid-loving plants. This means they need acidic soil and they certainly do not respond well to lime. When planting your rhododendrons, you can use a soil improver that makes the soil acidic and airy (DCM Vivimus for heathers, rhododendrons and all acid-loving plants or peat, for example). Peat also provides sufficient organic matter and nutrients to ensure a good start. The first year after planting rhododendrons, you will need to water them during a hot summer because of their shallow roots. From the second year, rhododendrons will have enough roots to get through a dry summer. The shallow roots can also get damaged quite quickly during hoeing.
Later you can apply a layer of peat around the plants every year to maintain the acidity level required for these acid-loving plants. This also prevents the soil from drying out and controls weeds.
Adding lime and sprinkling with hard water are obviously not recommended. You can add special fertiliser for hydrangeas and rhododendrons for good flowering and growth.
Not all rhododendrons prefer shade.
Rhododendrons do not do well near trees with shallow roots, such as birch and pine.