Featured Article
Join Our Mailing List
"How to" articles to help gardeners.


IntroThumb Greetings!
As summer turns to fall and you are out surveying your garden, learn how to spot your next  year's flowers on your rhododendrons. This article will also teach you how you can encourage more blooms on these King of Shrubs with food or light.
Flower Bud Identification
Mid-spring blooming rhododendrons make their flower buds in July to September, but will not open until the following year.  Many customers ask "Why didn't my rhododendron bloom?  They had flower buds!"  If you know what the difference between a flower bud and a leaf bud, you will not be surprised come spring as you will be able to recognize which plants have made flower buds the year before they bloom.  On most rhododendrons, flower buds are larger, and round like a marble.  Leaf buds are small and pointed.  There are exceptions, for example, on the Big Leafed rhododendrons, the leaf buds are large, causing confusion. And, on the tiny leaved lepidote rhododendrons like the species Augustinii, the flower buds are small and pointed.   Read on for some examples. 
Big Leaf Rhododendron's Leaf Buds
Fewer people grow these giants of the rhododendron family, and they are not to be confused with the more commonly grown hybrids.
These species plants have big leaf buds, fooling those hopeful gardeners into thinking they will see flowers next year.  Sorry...the real flower buds are usually bigger than golf balls that open to large trusses of light yellow, pink or white flowers.  Most of the Big Leaf Rhododendrons take at least 10 years to first flower, and many times much longer. An old timer rhody enthusiast once told me that if you put a bucket full of alfalfa pellets at the bottom of the hole, your Big Leaf Rhododendron will bloom in 5 years.  I haven't tried it yet. 
Small Leaf Rhody Flower Bud

Small Leaved Rhododendrons have small flower buds 


To confuse you even more, the small leaved rhododendrons, many dwarfs, have little pointed flower buds, but they are larger and more plump than the leaf buds.  On these types of rhododendrons, it is common to have mostly flower buds developing, however, in deep shade there will be fewer flower buds created.

Factors affecting Flower Bud Development in Rhododendrons - Light
We all want more flowers on our rhododendrons, so it is useful to know what to do to enhance flower bud development.  Light is the primary factor that will stimulate flower bud development.  You can dump a lot of fertilizer on a rhododendron that resides in a very shady spot, and not influence flower bud production at all. It is not necessary that your plants get direct sun, but they do need good light from the sky.  A  rhododendron planted on the edge of a forested area will flower nicely as long as above the plant you can see open sky.  If the plant is planted back under the tree branches where it is dark, it will not bloom much if at all.  Pruning tree limbs up so more light from the sky is available may cause your plant to start blooming more, then feeding and adequate watering will be useful.  Another thing to keep in mind is that your mid-spring blooming rhododendrons will need the adequate light in July through September, when they make their buds. If they are in shade at other times, that is not so crucial. And one last thing, adequate water is also important for flower bud development, especially if your rhododendrons are planted near greedy roots from large trees. 

Other Blooming Behaviors 


1. Very few flowers for 2-3 years after planting: Some rhododendrons that have been growing in a container for most of their life will find the freedom of a rich soil mix, plenty of water and good drainage

soooo good that they just want to grow some foliage for awhile. Also, flowering is the way plants makes seed to procreate, so if the plant is not feeling very threatened for survival thus needing to make offspring, then it may tend to produce more leaves.


2. Rhododendrons that bloom every other year: There are some varieties that bloom so heavily in the spring, they take a year off for a breather. This seems to be varietal dependent. In the "off" years, they have spotty blooming.  This doesn't seem to have anything to do with light or food.


3.Wetter than normal winters make for more flowers: We have noticed that our rhododendrons make more flowers after a wetter than normal winter.  This may be due to the overall plant health being enhanced, adding vigor. This is unlike fruit production where a wetter than normal spring keeps the bees away, resulting in a drop in fruit production.


4. Old established rhododendrons flower like crazy with no attention what so ever: You  may have noticed, if you live in an area with old established rhododendrons, that they flower every year, and usually heavily with no extra food or water given to them.  This is partially due to the genetics of these old hybrids, but mostly it is because they have established a dense, strong root system and can flower without much care. However, some of these older plants will become trees with fewer leaves and flowers over time, while other always look perfect.  The gangly ones will need occasional pruning, food and water.  In the photo below, taken in Queen's Park, New Zealand, you can see the old rhododendron on the left blooming heavily, while the other is 'spot' blooming.  This could be either a genetic difference, or a food issue. QueensPark2


Factors affecting Flower Bud Development in Rhododendrons - Food
We recommend that you feed your rhododendrons twice a year.  The first feeding in early spring gives the plants some energy for the upcoming bloom. We usually suggest Valentine's Day as an easy date to remember.  We have been told that this early feeding will promote larger flowers with more vibrant colors.  Whether this is true or not is not confirmed.  The other feeding we recommend is right after blooming.  This feeding is the most important for flowering as it is the one that will stimulate flower bud production. So if your plants are in good light, this feeding will give you more blooms...guaranteed!  We suggest using Father's Day as an easy date to remember.

Before and after in Flower Bud Development 


This first photo was taken in late May of this year of a new growth emerging just after the bloom. At this time, there is no indication of this bud being a leaf or flower bud. The same bud is shown in the second photo as a definite flower bud. This plant received just what it needed. This photo was  taken in mid August.  This flower bud will continue to become rounder and fatter as the season turns from summer to fall.  By late October the bud will be complete and will sit dormant waiting for the warmer spring days that will cause it to open and reveal the beautiful flowers within.


I hope this discussion was of some help to all of you rhododendron enthusiasts out there, and that you will pour a glass of your favorite wine and take a tour of your rhododendron collection this October to see which plants have flower buds for the upcoming spring.


Best Regards,


Don S. Wallace

Singing Tree Gardens & Nursery


You must print and bring this coupon to the nursery for redemption, and only one per customer.Coupon2