Caring for rhododendrons: three mistakes to avoid
Created: 05/30/2022, 16:00
By: Ines Alms
With good care, the rhododendron can grow to several meters.
If you water, fertilize and prune it properly, it will bloom like a champion.
Munich – The rhododendron is actually a lush flowering plant if it gets a partially shaded spot and good care.
If only the word "if" wasn't there.
Most problems with rhododendrons are not due to pathogens or pests, but to incorrect care such as a lack of nutrients, the wrong irrigation water or a cut at the wrong time.
Caring for rhododendrons: Mistake #1 – water with tap water
A well cared for rhododendron in full bloom (symbol image) © Manngold/Imago
Does your rhododendron have yellow leaves with dark green veins?
This could be because you have been watering with tap water that is too hard.
This increases the pH of the soil and the plant can no longer absorb the nutrients well.
It is better if you collect rainwater.
Also make sure not to water the rhododendron too little: it needs water every day, but does not like waterlogging.
Mistake No. 2: Fertilize incorrectly
Rhododendrons need the right fertilizer for a rich bloom, at least once a year.
The best time to do this is before flowering, between late March and May.
If it has rained a lot in the spring and the nutrients have been washed out of the soil, then another fertilization is recommended in late June to mid-July.
If rhododendron does not get enough nutrients, this can cause jaundice, for example.
Since rhododendrons do not like lime, it is of course important that the fertilizer does not contain lime either.
To be on the safe side, use a special - preferably organic - rhododendron fertilizer.
You can also recycle coffee grounds as an organic fertiliser, ideal for calcareous water and basic soil.
You should also avoid these mistakes:
Do not mulch rhododendrons: A layer of mulch several centimeters thick made of autumn leaves or pine or spruce bark keeps weeds away and enriches the soil with humus.
Compost as fertilizer: You should avoid this because compost contains lime.
Do not remove diseased buds: Brown-black buds indicate an infestation with rhododendron planthoppers.
You should collect such buds, otherwise the infestation will spread.
Lack of water in winter: Although most rhododendron varieties are hardy, they can die in winter due to lack of water.
If the ground is frost-free, you should therefore occasionally water the plant during longer periods of drought, even in winter.
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Mistake #3: Pruning rhododendrons at the wrong time
If the rhododendron does not grow at all or only slightly and loses its leaves in the lower part, this is a possible sign that it is not well rooted.
Then you shouldn't cut it either.
Also note that if you prune the rhododendron at the wrong time, you risk a fine.
A cut is actually not necessary.
However, if the plant thrives luxuriantly, you can tackle the wild growth from July to September.
In the spring, a cut only makes sense when the flowers have withered.
But beware, since all parts of the plant are poisonous, you should wear gloves when cutting.