Rhododendron, special flowered shrubs

Flowers gathered in bouquets 20 to 25 cm across, in pinks and reds through white and violet, open at the start of spring above leaves that stay handsome all year. Rhododendron is one of the finest shrubs for shade: give it acid, well-drained heath soil that never floods and it will grow old and majestic.

Rhododendron at a glance

Name	Rhododendron
Family	Ericaceae
Type	shrub
Height	1 ⅓ to 16 feet (0.5 to 5 meters)
Exposure	part sun and shade
Soil	acid, heath soil
Foliage	evergreen
Flowering	spring

Planting, pruning and caring for them are steps that help enhance blooming and avoid diseases.

Planting rhododendron

One of the most important considerations when planting rhododendron is the need to have heath and well drained soil.

If your soil is chalky or limestone soil, it is recommended to dig a much larger hole and fill it in with heath.

Rhododendron tolerates shade, part sun and even sunlit places, as long as it stays cool.

• We recommend planting rhododendron in fall.
  Planting is tolerated in spring or winter, as long as it doesn’t freeze.
  If you wish to plant in summer, provide for regular watering at the beginning.
• Choose a partially shaded or sunlit spot that never gets scorching hot.
• Avoid flood-prone areas at all costs, because this shrub hates sitting water.
• Follow our advice on planting heath plants and shrubs.

• Read also: Growing and caring for potted rhododendron

Propagating rhododendron

Making cuttings is the easiest and fastest technique to propagate rhododendron.

Preparing rhododendron cuttings can be done all summer long.

• Collect 6 to 8 inch (15 to 20 cm) cuttings from non-flowering stems.
• Remove lower pairs of leaves, keeping only the topmost one or two pairs.
• If you so wish, dip the base of the cuttings in powdered rooting agents.
• Place your cuttings in nursery pots filled with cutting soil mix.
• Keep the substrate moist and put the cuttings near light, but not in direct sunlight.

When to plant rhododendron: the four windows compared

Autumn is the season the article recommends, but three other windows will work if you take one precaution. Here is how each compares before you dig.

Whatever the season, avoid flood-prone areas at all costs, because this shrub hates sitting water.

Pruning and caring for rhododendron

It isn’t really necessary to prune rhododendron, so caring for them is easy.

Pruning is only needed if you wish to maintain the figure, reduce the size of the shrub, or balance growth:

• Remove dead wood.
• Remove wilted flowers regularly (deadheading).
• To reduce shrub size, wait for the end of the summer and cut just above a bud so it will split into multiple branches.

It is important for the soil to remain slightly moist at all times, and for that the best solution is to mulch with pine bark mulch.

Problems with growing rhododendron

Rhododendron leaves and buds turn brown

This is often due to poorly-draining soil, which means water is stagnating around the roots.

• Rhododendron must never have stagnant water around its roots, water must flow away quickly.
• It makes sense in this case to mix some sand into the soil. It especially helps to spread a layer of clay marbles or pebbles at the bottom of the hole to help water seep into the ground.

Rhododendron is actually more hardy than they are able to overcome excess water in the ground…

Finally, fertilizing with special heath plant fertilizer at the end of winter strengthens rhododendron, enhances their flowering and helps avoid diseases.

Leaves lose their color and turn yellow

This is generally due to excessively chalky soil, and results in what is called rhododendron chlorosis.

• Adding a layer of heath the soil in the surface is recommended.
• A supplement of heath plant fertilizer should also help cure the chlorosis.

Diseases and parasites attacking rhododendron

Rhododendrons are shrubs that resist diseases well when they are well settled in, roots have developed well, and growing conditions are favorable.

Inversely, if there is either excess water or excess heat, or it hasn’t been planted correctly, it is more vulnerable to various diseases, listed below:

Rhododendron withers, looks sad and stunted

This is one of Rhododendron’s most common diseases, and it is often too late when it shows.

• It is usually due to a fungus that is called Phytophthora cinnamomi. This fungus often is lethal to rhododendrons.
• Treatment must be swift and merciless, removing and destroying the infested portions of the shrub, but survival chances are slim.
• Once all infested portions have been removed, treat with systemic fungicide, which is the only effective option against this fungus.

Blisters form on leaves

• Even though this is not often critical, this fungus-based disease is due to Exobasidium vaccinii, and is more commonly called leaf gall.
• Usually, it is enough to remove the leaves that host these blisters.

Choosing a rhododendron: sixteen widely sold varieties compared

Garden centres carry a fairly settled cast of rhododendrons, from head-high woodland giants to dwarfs that sit happily in a pot of ericaceous compost. Use the table to match flower colour, eventual size and flowering time to the spot you have in mind.

Learn more about Rhododendron

This is probably one of the most beautiful flowering shrubs to decorate your garden.

Rhododendrons boast amazing flowers at the very beginning of spring, and their leaves are gorgeous all year round.

This plant can grow to live very old and can even reach majestic sizes, some shrubs reaching heights of over 16 feet (5 meters).

Rhododendron flowers are grouped in bouquets that can span 8 to 10 inches (20 to 25 cm) across, with hues shifting in ranges of pink to red, including white and violet depending on the species.

Rhododendrons are particularly decorative, and are among those shrubs that are best suited to shaded areas.

• Read also: Growing and caring for potted rhododendrons.

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