Rhododendron/Azaleas

Did you know that the word RHODODENDRON comes from Greek (rodon) meaning rose and (dendron) meaning tree. Now you can understand why so many rhododendrons can be the size of trees.

Rhododendrons and Azaleas are a genus of evergreen and deciduous shrubs; they are part of the ericaceae family. Ranging in size from large-leaved to dwarf species, some are fully hardy to frost tender.  They are shallow rooted plants which like acidic soil, and most importantly moist soil.

Rhododendrons became very popular in the UK in the early 18th century. Unfortunately rhododendron ponticum, which originated from the Black sea region has become very invasive and is a problem to the ecosystem of our native flora.  Here in the garden we are gradually taking ponticum out.

Take a closer look at the leaves of rhododendrons and you will notice some have Indumentum and Tomentum.

Indumentum (Latin garment) is a velvety layer of fine woolly hairs on the underside of some leaves, which plays a role in protecting the plant from moisture loss and also provides a physical barrier to pests. Usually a brown cinnamon shade,

Tomentum is a coating of fine hairs but on the upper part of the leaves. More prominent on emerging leaves, it provides protection from harsh weather and pests, but can be mistaken for mildew by some gardeners.

Rhododendron leaf shape

They can be rounded, oval or pointed and tend to be quite thick so take longer to break down. Leaves play an important role in protecting the plant; typically you can see very curled up leaves on cold icy days then once the heat builds they will uncurl.

In the garden you will find large leaf varieties of Rex,Sinogrande, Indumentum, varieties of

yakushimanum, bureavii, and Sir Charles Lemon.

Azalea leaves tend to be thinner.

Flowers can be large and showy on some varieties while others tend to be smaller, also some have an amazing scent. Flowering time is usually April to June but recently we have seen them beginning to bloom as early as February.

Types of diseases to look out for:

Phytophthora

Honey fungus

Bud blast

Powdery mildew

Leaf spots

Silver leaf.

Types of pest:

Scale insects

Aphids

Vine weevils

Pamela Bruce - Gardener