Arno KingHow to prune vireya rhododendron

I was strolling around the gardens at Stringybark Cottage on Queensland’s Sunshine Coast) with owner Cheryl Boyd when I was engulfed by a powerful perfume with which I was unfamiliar. Cheryl pointed to a group of Vireya Rhododendron (‘tropical rhododendrons’) growing under some gum trees in the garden.

Vireya Rhododendron

Vireya Rhododendron

Vireya Rhododendrons grow under Eucalypts in bony soil at Stringybark Cottage

Vireya Rhododendrons grow under Eucalypts in bony soil at Stringybark Cottage

This is one of her ‘tricky spots’ – bony soil – heavy competition from tree roots – dry – you know the story. However the rhododendrons were thriving. The large dense bushes with deep blacky-green leaves were topped with flowers in various colours. Cheryl pointed out that this was one of the best flowerings in years – possibly caused by the continuous dry weather we have been having.

Some of the rhododendrons were past their prime and Cheryl proceeded to bend and snap the branches as we were talking. I was fascinated by this procedure and Cheryl informed me that she had learnt it from rhododendron grower Graham Snell who had a Vireya rhododendron nursery on the road between Maleny and Mapleton in Queensland and found that this technique made a great difference to the plants’ growth.

Cheryl snaps straggly branches following flowering

Cheryl snaps straggly branches following flowering. You can see the snapped, hanging branch in the cetre of the photo

If you simply prune the branches, they will generally only form one leader or abort completely. However if you bend and snap the branches, some sap still flows to or from the main plant and the dormant buds are more likely to become stimulated, grow and produce multiple branches. The bent branches can be pruned off once new growth shoots away.

Cheryl tries to snap above the last node with leaves on it. Sometimes she will snap into older leafless branches but this can be unpredictable and she would only try this in spring or early summer.

Branches are snapped and left in a vertical position

Branches are snapped and left in a vertical position

Cheryl’s plants certainly seem to have benefitted from this pruning procedure and are dense, full and vigorous.

I have since discussed this procedure with a number of horticulturists who have, surprisingly, dismissed this procedure. This has prompted me to investigate every Vireya rhododendron plant I have come across since – and they are not a common plant in gardens in South East Queensland.

Other plants I have inspected are generally not vigorous or shapely. In most cases the ravages of pruning are clearly visible and these plants have remained spindly and have poor form. When I look down into bushes I see stubs of branches that have aborted and stubs with a single lanky branch.

Cheryl’s technique certainly seems to work and should be more widely used with these and other ‘difficult plants. I suspect other plants worth trialling it on include some Medinilla, some of the subtropical Illicium, and shrubs in general that make sparse ungainly growth and do not appear to respond to pruning.

Vireya Rododendron

Vireya Rododendron

Cheryl generally grows her Vireya rhododendron in short (approximately 300mm high) hollowed-out logs filled with organic matter. Their roots can grow down into the soil below, but the plants are guaranteed free drainage and the plants’ crown is elevated. Most Vireya rhododendron grow as epiphytes (plants which grow on trees, high in the forest canopy) and Cheryl tried to emulate this in her garden.

Vireya Rododendron closeup

Vireya Rododendron

Cheryl uses Nutri-store Gold (Nutri-tech Solutions) to fertilise her garden and this biological fertiliser contains most of the essential minerals for plant growth and encourages biological activity in the soil. Given their background, these plants probably have strong mycorrhizal fungi associations that may be harmed by many of the conventional fertilisers.

Cheryl waters the garden during dry periods – which has been regularly during recent months.

You will see a feature on Cheryl’s Garden, Stringybark Cottage, in January’s ‘Gardens Illustrated’ (a UK publication). It will shortly be available in newsagents.

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Arno King

About Arno King

Landscape architect, horticulturist, journalist and keen gardener, Arno is a regular contributor to Subtropical Gardening Magazine. Based in Brisbane, Arno grows a wide diversity of unusual plant species and has particular interests in growing edible plants in creative settings and biological and organic gardening. Brisbane, Queensland

14 thoughts on “How to prune vireya rhododendron

  1. Sue English on said:

    I wonder if this would work for azaleas? They’re related aren’t they? Not sure what to do with some that have got really tall and straggly with a lot of leafless wood in the middle. Not game to cut them back hard though that’s what I’m tempted to do.

    • Arno King on said:

      Hello Sue

      I am sure this would work with azaleas – which are also in the same genus – Rhododendron.

      Azaleas are a varied lot, and while some are vigorous, other cultivars are not. I have seen many examples of azaleas that have been heavily pruned and have not responded well to it. I would be inclined to approach the pruning slowly and in stages.

      Arno

  2. Vireya on said:

    Fascinating! I will give this a try. I have quite a few vireyas, many of which are quite spindly. The bushiest one might just be that way because branches have been broken by my dogs walking past. Perhaps they have been doing me a favour all this time.

    • Arno King on said:

      Hello Vireya

      Yes, your dogs may just be on to something here. Follow their lead and let me know how it goes.

      Arno

  3. Yes I agree, that’s fascinating. I’ve never heard of such a thing but I’m going to try it on mine. Thanks Arno.

    • Arno King on said:

      Hello Helen

      I had not come across this technique myself, and I have never seen it mentioned in print. Hence I thought I should share it with readers.

      I learnt this weekend that Rhododendron grower Graham Snell – the guy who taught Cheryl this process – died a few years ago. If we don’t share these techniques around, they can readily be lost.

      Arno

  4. Kate Wall on said:

    Thanks Arno for an excellent article!!! I look forward to trying this out and also didn’t realise that the vireyas were epiphytes – that makes a difference for those of us with heavy soils.
    Sue – do cut the azaleas back, I have done recently and they have all reshot from the base and look better than ever, even though we have had such a dry summer.

    • Arno King on said:

      Hello Kate

      It makes all the difference knowing how plants grow in the wild. I love to travel and a highlight is to come across plants I grow in my garden or know from cultivation growing happily on their own. It gives you great in sites and often helps explain some of their idiosyncrasies.

      If you have heavy soil, your Vireyas will enjoy growing on mounds of amended soil or in raised beds.

      Good luck with these plants.

      Arno

  5. REALLY INTERESTING Arno … and I wonder if this might be an adaptation of other epiphytic, lithophytic and forest floor plants like medinilla (as you suggest) to branches that fall on them after a storm. Damage would most likely not make clean breaks over all points of contact by, say a falling branch. Rather, just severely bent only, allowing the process you describe and a much “improved” habit with more flowers.

    Definitely trying in combo with Cheryl’s “in log” growing condition … Thanks huge for the feature, has renewed my interest in these lovely flowering & scented (some) plants. I’d all but given up on as “too hard basket” trying to make adequate drainage and overcome their spindly habits .. LOVE YOUR WORK !!!

    • Arno King on said:

      Hello Peter

      My limited exposure to Vireya Rhododendrons in the wild has been of plants that they do tend to be a little straggly and open in growth. In garden situations this may not be quite the ‘look’ we are after.

      I consider that the procedure noted above is somehow triggering the production of auxins, or similar plant stimulants which would not be produced from a cut stump. This would be a great research project for a uni student. As discussed, I think there are many plants which could be treated in a similar way and these include many native species from heath and schlerophyl forests.

      I have just been in Auckland, New Zealand and many Vireyas are in full flower over there right now. While they are more widely grown in that country, they are also regarded as being a ‘little tricky’. This generally means that we need to learn a little bit more about their cultural needs.

      Arno

  6. Paul Urquhart on said:

    The Gardens Illustrated article is on page 77 of the January issue. I get it online. Saves paper and it’s always there on my iPad.

    • Arno King on said:

      Thanks Paul

      I am still buying the paper copies, but I am also running out of room in the house for all those books and magazines. I enjoy the feel of the paper copy, but I may need to change my ways.

      Arno

  7. Jeanne on said:

    Thanks so much! Am 79 and moved subtropics 16 yrs ago. Now I know what to do with my straggly vireyas in pots. Plant them under gum tree and bend them over! Love my semi tropical garden.

    • Arno King on said:

      Hello Jeanne

      I’m glad my article has inspired you with your plants.

      Remember to also give them a good feed. I have noted Cheryl’s feeding regime above.

      Arno

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