Rhododendron & Extravagance. These two words come into mind when you see wonderful fountains of pink and white, peach and yellow, rose and lavender, crimson and maroon Rhododendron blooms.
The name Rhododendron comes from the greek words “rodon” which means “rose” and “dendron” which means “tree”, so it is a Rose Tree.
There are more than 31,000 varieties of Rhododendron plants which are often known as the King of Shrubs .
What do you need to know about Rhododendron? Here are some Q & A that will help you in growing these wonderful plants.
1. When is the best time to plant Rhododendron?
* You can plant them in spring or fall.
2. How fast does rhododendron grow?
* Rhododendron usually grows slow and can be kept in a small bushy habit for some time.
3. What can you grow under rhododendron?
* A large number of ground covers will work – vinca, lamium, aegopodium, pachysandra, hardy cyclamen, or sweet woodruff.
4. Can I move mature rhododendron?
* Slice around it and drag to better spot. Tight, fibrous shallow roots make rhododendron easy to move.
5. How much water does Rhododendron need?
* Rhododendron needs plenty of water, especially in hot dry weather and when it is in full growth.
When you plant, dig in plenty of organic matter such as leaf mould or compost. This will help retain moisture in the soil.
Using pine needles (acidic pH) as mulch works to help keep the soil moist, and maintain/add acidity to the soil. Roots are shallow, so mulching will help to keep the weeds down, without disturbing the root system.
Newly planted rhododendron should be watered in well, and will require more attention in their first season than well-established ones. Rhododendron that is suffering stress due to drought will show it by wilting.
6. When is the best time to prune rhododendron?
* The best time to prune rhododendron is right after the flowers fade. Then, the new growth that occurs after pruning will have time to set flower buds that will bloom the following spring.
Plants that are getting too big or have become leggy can literally be cut to 6 inches above the ground and will quickly bounce back with thick branching.
7. When is it better to move rhododendron?
* Sometimes it’s a better idea to move rhododendron rather than cut it back. Rhododendron that is too tall for the space usually grows back so quickly that, by the time it is ready to flower again, it is bigger than before you pruned it.
If you want to move a rhododendron to a better situation, it’s best to do it before it starts growing actively .
8. My rhododendron did not produce any blooms this year- it is healthy otherwise. Why?
* Too much shade. This is very common in North America where, in order to regulate sun and soil temperature, plants are placed in deep shade.
This allows healthy, if straggly growth, but can inhibit flowering. The more light you can give a plant, the more likely it is to flower.
9. My rhododendron has black spot, rust. Is there a plant medicine I can put in the soil so it will get absorbed by the entire plant rather than spraying every other leaf.
* I am sorry to hear about your sick Rhododendron. You should take a take a leaf sample into a Master Gardener clinic for (free) diagnosis.
10. Is rainwater better compared to tap water?
* Rain water is better. Tap water is often treated to make it alkaline, if it’s not alkaline naturally. If you can’t get enough rainwater and your tap water is alkaline, add a couple of cc of vinegar to each watering-can, but no more.
11. How to mulch rhododendron plants?
* Rhododendrons provide a natural mulch with their fallen leaves. Do not remove this as it adds required nutrients to the soil.
If you live in warm or dry climate supplementary mulch such as pea-straw will help to retain soil moisture. Mulch after the ground has warmed – to suppress weeds and to retain moisture.
Never mulch over dry soils but wait until a rain shower or the hose has thoroughly dampened the ground. Some mulch materials can deplete nitrogen as it decomposes; the signal is leaves that begin to yellow.
Never use mushroom compost as this is alkaline and rhododendrons are acid-soil loving plants.
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Yours truly, Polly – Organic Gardener