Bonsai Tonight

An educational website about bonsai development

Which pine species can I decandle?

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Decandling is a great technique for refining selected pine species trained as bonsai. At its most basic, decandling refers to the removal of spring growth with the aim of stimulating summer growth (see “Decandling” for details).

Black pine shoot

Decandling a Japanese black pine

As great as this technique is, its full application is limited to a small number of species. The aim behind this post is to provide a reference that indicates how different species respond to the technique.

Over the years I’ve worked with a number of different pines and have learned which respond well to decandling and which don’t. That said, there are far more species that I haven’t worked with or haven’t tried decandling. For these species, I’d love to hear your suggestions for where these trees fit in.

I’ve created four simple categories below but will be updating this post as more information comes in. I’ve also noted which species I’m less familiar with as an encouragement for your contributions.

For more about different approaches to managing spring growth, see “Approaches to managing new shoots on pine bonsai.”

Pine species that respond reliably to decandling

Healthy specimens of the following species can be decandled annually with relatively predictable results.

  • Japanese black pine, Pinus thunbergii
  • Japanese red pine, Pinus densiflora
  • Pitch pine, Pinus rigida (no direct experience)
  • Loblolly pine, Pinus taeda (no direct experience)
  • Slash pine, Pinus elliottii (no direct experience)
  • Long leaf pine, Pinus palustris (no direct experience)
  • Short leaf pine, Pinus echinata (no direct experience)

Pine species that can benefit from decandling techniques

The pines in this category can respond well to decandling, but not in all cases. Tree age, stage of refinement, or the climate in which the tree is grown may affect results.

  • Corkbark Japanese black pine cultivars
  • Dwarf Japanese black pine cultivars
  • Monterey pine, Pinus radiata
  • Scots pine, Pinus sylvestris (no direct experience)
  • Aleppo pine, Pinus halepensis
  • Italian stone pine, Pinus pinea

Pine species that may benefit from limited decandling techniques

Pines in this category don’t reliably produce summer growth after decandling, but the technique may be useful to stimulate back buds.

  • Virginia pine, Pinus virginiana (no direct experience)
  • Austrian black pine, Pinus nigra
  • Pinyon pine, multiple species (no direct experience)
  • Mugo pine, Pinus mugo (see reader comments below for tips relating to mugo pines)

Pine species that do not typically respond well to decandling

Decandling techniques may be applied to the following species in limited situations, but the trees are less likely to respond like the trees in the categories above.

  • Japanese white pine, Pinus parviflora
  • Ponderosa pine, Pinus ponderosa
  • Limber pine, Pinus flexilis
  • Bristlecone pine, Pinus longaeva
  • Foxtail pine, Pinus balfouriana
  • Western white pine, Pinus monticola
  • Shore pine/lodgepole pine, Pinus contorta

The above list is not complete. If you have questions about pines that do not appear on this list, note them in the comments below and I’ll make updates as more information comes in.

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Comments

  1. Well, thank you very much for this once again great post.But, I cannot agree with the harm, decandling a mugo may/can cause. I’ve been doing it for a couple of years, and they all respond very well.
    Regards, Thomas

    • Thanks, Thomas, that’s great to hear! I’ve seen many mugo die back after decandling or, in the best cases, produce buds that opened the next year. I’d love to know more about your approach!

      • Absolutely agree! To induce backbudding on mugo, i cut all candles completely at once just before the needles open up. In Belgium that’s around end of June. New buds are ready in September/October and ready to be selected in winter and grow next spring.

      • Hi Jonas,
        I “inherited” two Mugos a couple of years ago. Unfortunately, they were not properly taken care of, resulting in several elongated shoots with rarely needles, due to several periods of blooming.
        I then shortened the elongated shoots to appropriate buds, creating a more dense tree. I also decandled them every early summer, which produced a very strong back budding.
        They are still fertilised throughout the year, but I now reduced the decandling to a more balancing shortening. I shorten the candles to the length of the shortest ones.
        Both Mugos still produce new buds and back budding. New buds at the shortened candles produce at least two new bud, so I have lots of material and choices for the development of branches (lucky me).
        But, you are absolutely right, new buds appear through summer and only open in the following season. I always thought this is mainly because Mugos are single flush pines…?
        And, I do have to say that I am living in Germany, so maybe weather conditions may play a major role as well.
        All the best wishes, Thomas

      • Thanks Thomas! This is a good reminder that the techniques can vary widely based on when and how much we cut from the tree, let alone what we expect the results to be. There are some good general principles here that’s making me re-think how to present the info. In the meantime, I’ll be curious for more info on how your approach might work in my climate!

  2. Hi Jonas,
    Regarding aleppo pine, my experience is different. They are being decandled regularly with very good results. They can have even 3, 4, 5 flushes of growth a year here and in an experiment, they were decandled twice in the same year successfully. We treat them as black/red pines here in terms of work schedule. There are genetic variables and some respond better then others though.
    I can send you pictures of decandled pines with plenty of new buds on each end from this year if you like.
    Cheers,
    Shay

  3. Hi Jonas
    In Malta the Aleppo pines respond very well to decandeling. Apart from multiple new candles, They will backbud very well after decandling, especially if not yet very mature.
    Italian stone pines the same.
    They both need hot , sunny environments to thrive.

    • Thanks Joe! I think that’s the problem where I live – it may not get hot enough for the trees to respond reliably to the technique. Will keep trying!

      • Well the other side of the coin is that we can’t keep many other pines here. When the environmental conditions haven’t been adapted by the trees it is a long lost struggle.

    • Thank you Steven – this is a helpful video. I’ve seen Scots respond well to decandling, particularly trees in earlier stages of development, but I haven’t seen as many examples of refined trees that are decandled year after year. Will be on the lookout for it!

  5. Hi Jonas
    I have good luck with decandeling loblolly pine as well here in Virginia. They readily back bud. I am trying to bonsai them; although I am not as professional as you are and they are still very eary on in their development stage.
    Jan

  6. Jonas-
    I have an older Scots pine that responds quite well to decandling. I have never done a complete decandling, only the areas where growth is vigorous and I wishto balance out the tree. I agree with another poster that Scots pine back bud very well on older wood. They also respond well to frequent feeding.
    Thanks for the article.
    Terence

    • Hi Terence – that’s great to hear about the Scots, I’ve seen similar results. It seems like it’s a great species for decandling but maybe not with the same approach we use for black pines.

  7. Hi Jonas,

    This is a really interesting subject. Looking at your lists it seems like there is a general (if very imperfect) gradient from warmer lowland environments fostering species which respond positively to decandling, to cooler upland environments hosting species which do not. What are your thoughts on this?

    • Hi Loren – It’s definitely a consistent trend. Trees with longer growing seasons and available summer water seem to respond best to decandling. This categorization isn’t perfect – shore pine, for example, doesn’t respond as well to the technique – but it’s the best way to group the trees that I know of. Maybe over the coming years more people will experiment with a broader variety of pines and provide info that we can use to identify the best approach for given species.

  8. Monterrey Pine experience: For a time, I used a twice de-candling and then fall tinning on a Monterey Pine at the The Bonsai Garden at Lake Merritt, Oakland California, USA. My teacher Dennis Makishima recommended complete de-candleing when the needles emerged in mid Spring (April here) , remove all but four modest shoots per node at the end of Spring (June) , then thin to two appropriately sized -usually the smallest – at the end of the growing season, late summer (September). This worked far better than the usual Japanese Black Pine schedule of one spring de-candleing followed by fall thinning; he vigourus regrowth just overwhelmed that approach and the tree always looked pollarded. Like the Aleppo & Italian Stone Pines in previous posts, the Monterey Pine thrives here in the lower lattitude (like Malta) mild coastal area with long growing season. in it’s former range with irrigation. (The current natural range only where summer fog-drip is reliable). Note this tree spent decades in a container, was/is too big to be a bonsai so had been planted in the land there a few years earlier (1999). It had very thick plated bark with added rooting volume invigoration its trunk is swelling so fast that the bark is beginning to shed. Back then the Curator at BGLM, Kathy Shaner, was in favor of root pruning or even replanting in buried vessel or on a slab to facilitate root pruning. To volunteer, contact me at the email address below.

  9. Jonas. the earlier submission has a lot of typos. Here’s the proof-read version:
    Monterrey Pine experience: In the early 2000’s, I used a twice de-candling and then fall thinning on a Monterey Pine planted in the ground at the The Bonsai Garden at Lake Merritt (BGLM), Oakland California, USA. My teacher Dennis Makishima recommended complete de-candleing when the needles emerged in mid Spring (April here), followed by removing all but four modest second wave candles per node at the end of Spring (June) , followed by thinning to two appropriately sized shoots – usually the smallest – at the end of the growing season, late summer (September). This worked far better than the usual Japanese Black Pine schedule of one spring de-candleing followed by fall thinning; the vigorous regrowth just overwhelmed that approach and the tree always looked pollarded.

    Like the Aleppo & Italian Stone Pines in previous posts, the Monterey Pine thrives here near it’s natural range with irrigation in place of fog harvesting as in the hills above Monterrey. Here it’s in a lower latitude (equivalent to Malta) mild coastal area with long growing season. I’ve even seen Monterrey and Japanese Black Pine push latent buds through old bark in certain conditions in our area..

    Note this tree at BGLM spent decades in a container, was/is too big to be a bonsai so had been planted in the land there a few years earlier (1999). It had very thick plated bark, but with added rooting volume invigoration, its trunk is swelling so fast that the bark is beginning to shed. Back then the Curator at BGLM, Kathy Shaner, was in favor of root pruning or even replanting in a buried vessel or on a slab to facilitate root pruning. With a crew of volunteers and a a chain falls hung from a tripod, this is doable. Anyone interested in volunteering for this up-sized application of bonasi techniques may contact peterthomasbowyer at hotmail.com

    • Thanks, Peter! I worked on Monterey pines in the ground for years and found them a lot of fun to work with. They develop quickly and have great bark. I think some of the techniques you outline could apply to bonsai too!