By Pat Lea
Q: I see other folks’ rhododendrons blooming well. but mine never seem to bloom. What can I do?
A: As with most gardening problems, there is rarely a single answer.
First you should take an inventory of the living conditions of your rhododendrons.
Are the plants healthy in general? If your plants appear to be in reasonable health, they should be able to bloom.
Do they have good green unbitten foliage, strong stems and undamaged trunks? Cracked, broken or ice-damaged trunks or stems could mean no energy for blooming.
Any signs of insects chewing, such as leaves with holes or ragged-looking edges or sawdust near stems? Treat your insect problems, and plant vigor will increase.
Also, make sure that deer are not chewing the buds off.
Next look at overall sunlight and even moisture. Rhodos prefer semi-shade or cool, morning-only sunlight. Limited afternoon sun may not be harmful, but long, hot, western afternoon exposures can bake the plant and dry it out, limiting the ability to bloom.
Rhodos require even soil moisture. They suffer when planted in the root zones of certain thirsty trees such as maples and dogwoods that also create deep shade. They will require extra moisture supplied by you in areas that face drying winter or summer winds and thirsty tree roots. If a rhododendron is under stress, it can drop its buds or not produce them.
If your plants are in a situation that should be good but they are still not blooming, then a fertilization with a blooming-type fertilizer is on order. Make sure any fertilizer is gently diluted so as not to burn the root system. You can apply a ferrous sulfate, like Greenol Liquid Iron, a liquid that will green up foliage if lack of iron is the problem.
E-mail Pat Lea at lea.pat@gmail.com.