Key features
Final size2 x 2 metres in 20 years
FoliageLarge leaves year-round (evergreen)
FlowersPink flowers
PositionPart shade
SoilRequires moist yet well-draining acidic soil
Description
‘Cosmopolitan’ is a lovely, easy to grow evergreen shrub and one of the first Rhododendron to bloom in the spring. The insides of its pink, trumpet-like flowers—which sit in trusses—are embellished with a rich, bespeckled red. Alongside its flowers it grows deep, glossy green leaves for year-round interest. Requiring little maintenance, ‘Cosmopolitan’ is dense and bushy and, unlike other Rhododendrons, is prone to reflowering in the autumn.
This evergreen Rhododendron will grow to approx. 2 x 2 metres in 20 years and is suited to containers, small spaces or borders with neutral to acidic soil.
Planting Steps
1Preparation
- Pot-grown plants can be planted at any time of year, whereas bare roots need to be planted between November and March.
- Clear weeds and grass within a metre of the planting hole.
- Dig a hole as deep as the root mass and twice as wide.
- To help your plant establish more effectively, sprinkle Rootgrow in the hole.
2Planting
- Gently loosen the roots and place into the planting hole.
- Ensure the top of the plant’s compost is flush with the level of the surrounding soil and the graft union or collar of the tree is above ground level.
- Mix 50% of the original soil with 50% compost.
- Fill in the hole, firming the soil gently.
3Last Steps
- Water generously around the base of the plant.
- If you are planting either a single stem tree or mature standard tree, we recommend adding a staking kit and rabbit guard.
Aftercare Advice
Rhododendron and Azalea are generally low maintenance however they will require a good watering regime for a couple of years whilst they establish. Water well and regularly through spring and summer, increasing in hot or dry weather. If planting in autumn, you may only need to water a little. Rainwater is preferred but tap water can also be used. It is advisable to keep the area free of competing weeds and grass during this period.
Rhododendron and Azalea are acid-loving plants so when grown in acidic soil are unlikely to need additional feeding. However, if the acidity of your soil is low, iron, manganese and magnesium treatments can be added to prevent browning and yellowing of the leaves. Potted Rhododendron and Azalea may also benefit from a slow-release granular fertiliser which provides an on-going support of nutrients.
Most Rhododendron and Azalea belong to RHS ‘Pruning Group 8,’ meaning they require minimal pruning. After they finish flowering, you should remove any deadheads and address any diseased or damaged branches, but otherwise, they should be left unpruned.
For more detailed advice and video guides, please visit our Help & Advice section.
