When To Plant Rhododendrons In The UK


The best time of year to plant his much-loved flowering shrub is in the spring or early autumn when there should be a good amount of moisture in the soil to help your plant to settle in.

The main surge of sales for rhododendrons is in the spring just before they burst into colour.

Some recommend that you should buy a rhododendron when it is in flower. However, I find that the colours on the labels nowadays are very close to what the actual colour of the flower will be.

And if you buy one in bud you get the enjoyment of watching it spring into action, with the added bonus of a longer flowering period too.

Where To Plant Rhododendrons

Rhododendrons prefer a sheltered position in dappled shade, but avoid planting in deep shade beneath other trees.

They will thrive in moist but well-drained, acid soil with a pH level between 5 & 6 that is rich in organic matter.

If you have chalky soil in your garden you can grow them in a large pot full of ericaceous (lime-free) compost.

Avoid planting in a position where it will receive the early morning sun, and where there are frost pockets in your garden, as this can cause damage to the buds which can lead to the plant failing to flower.

How To Plant Rhododendrons

  • Before planting your rhododendron work plenty of organic matter into the soil, leafmould or composted bark or conifer needles are best. If you have none to hand then purchase a bag of ericaceous compost, which is a mixture of green waste, peat and fertiliser.
  • Do not plant your rhododendron too deeply as they are a surface-rooting and the roots should be just covered. The soil should be compacted down and not stamped on.
  • Apply at least a 3in (8cm) mulch of chipped conifer bark, the mulch should be well-aerated and not packed down. Replenish the mulch each spring when the soil is still moist.
  • When planting rhododendrons in pots it is a good idea to mix in some perlite with the ericaceous compost to aid with drainage.

How To Water Rhododendrons

Rhododendrons thrive in areas of high rainfall, so when possible only water with collected rainwater. When this runs out in the drier months tap water will suffice for a month or two in the summer months.

The reason we don’t want to give our rhododendrons too much tap water is that it contains too much calcium which reduces the acidity around their roots.

How To Feed Rhododendrons

I have always fed my rhododendrons with an ericaceous fertiliser in spring, with the addition of a controlled released fertiliser pellet added to the soil as well.

When To Prune Rhododendrons

Rhododendrons require minimal pruning other than the removal of dead and diseased wood.

If you need to prune your rhododendron to restrict its size, then this is best carried out immediately after flowering in the spring.

The reason being that rhododendrons set next year’s flower buds by mid to late summer, and removal of these buds will lead to a flowerless shrub next spring.

After pruning your rhododendron give it a feed, mulch and keep well-watered to encourage new growth.

If practical deadhead the spent flowers of your rhododendron taking care not to cut past that first leaf where next year’s buds will be forming.

Rhododendrons FAQ

Why Is My Rhododendron Not Flowering?

Rhododendrons set their buds for next spring’s flowering period in the previous summer. Dry conditions in this period can cause the buds to partially form or fail to form completely.

Prevent this by making sure your rhododendron is mulched and watered thoroughly during any dry period in the summer.

Why Is My Rhododendron Dropping Its Leaves?

Each year your rhododendron will shed a proportion of its foliage during the spring and summer, mainly older leaves. This a normal occurrence with all evergreen shrubs and is no cause for concern.

Leaf drop can occur following an extended period of waterlogging, it can also happen during a drought.

The oldest leaves are first to drop, leaves higher up the plant may also show signs of browning on the edges or the tip. of the leaf.

Why Is My Rhododendron Drooping?

During a cold snap, your rhododendron’s leaves may droop, but should usually recover when milder weather returns.

Why Have The Leaves On My Rhododendron Turned Yellow?

Yellow leaves on your rhododendron often represent the plant’s distaste with its care.

There are three main reasons why your rhododendron is unhappy:

  1. Planted where there is poor drainage.
  2. Planted too deeply.
  3. Nutrient deficiency – causing yellow foliage known as chlorosis.

4 Rhododendron Facts

  • Rhododendron derives from Ancient Greek ῥόδον rhódon “rose” and δένδρον déndron “tree”.
  • They are a genus of around 1,000 species of woody plants in the heath family (Ericaceae).
  • Found mainly in Asia and the highlands of the Appalachian mountains in North America.
  • It is the national flower of Nepal, as well as the state flower of Washington and West Virginia.