Callistemon sieberi – flowering

This year’s flowers have just started to open on this tree during the week so I thought I should share it with you.

Callistemon sieberi ‘waterswept’

The branches look a bit untidy at the moment. Callistemon flower on the tips of the shoots that grew last year. For many years I kept it well trimmed but, of course, was cutting off all the potential flowers every time I pinched the shoots. With advice from Derek, a master with Aussie plants as bonsai, I learned to allow the shoots to grow and mature so it can produce flowers. After flowering it is pruned quite hard then new shoots are again allowed to grow and mature for the following year’s flowers.

You will note that the flowers on this species are rather less impressive than many we see in gardens but I think the pale pink blush is nice on this bonsai. Flowers are also smaller than many which fits in well for a bonsai sized tree.

4 thoughts on “Callistemon sieberi – flowering

  1. I have a fairly mature Callistemon species – don’t know what type as it was a hand-me-down bonsai rescued from a shopping centre plant tub when they were being thrown out.
    It seems that one years shoot growth doesn’t produce a flower as you describe. I tried for several years to prune in autumn and hope that the growth into spring would produce the goods – but shoots only extended and no flowers appeared. This time I let it go completely for another year – no pruning. The four largest ‘branches’ extended this spring and about a month ago produced a flower. They were red. Now I know that at least.
    Do you have any experience that suggests a critical pruning time, fertilising regime, species peculiarity or something else that would help explain my experience ?

    • As far as I am aware all Callistemon flower on growth from last year so yours should too given the right circumstances. The secret is pruning only in Spring and early Summer then leaving the resulting new shoots untouched until the following spring. The WA native bonsai guru, Derek, told us to prune hard immediately after flowering then leave the subsequent shoots to grow untouched until they flower the following spring. For those of us who are used to pinching often to keep a nice neat outline it can be difficult to leave the lengthening shoots alone but this is the method I have followed and it does work. You can see that my Callistemon is quite untidy at flowering time. I have removed some of the shoots without buds just before it flowered so the flowers are shown a bit better but that is the only pruning it has had since last spring. Other flowering species produce more, better flowers after fertilising with high K (potash) fertiliser and Callistemon also seems to respond. There is no specific flowering bonsai fertiliser but anything that is aimed at flowering or fruiting plants – azalea, rose, tomato, citrus, or just ‘flowers and fruit’ fertilisers are all pretty similar and have the higher levels of K that are required to stimulate flower bud formation. Note that flower buds are actually forming during the autumn before so use your high K ferts during late summer and autumn for best results the following spring.
      Good luck,

  2. Thanks Neil.
    It would seem that my timing could be the main issue – pruning too late. This year – by chance – I did prune quite hard in mid November, so I might be on track for a better outcome next spring. I’ll try to be a bit more conscientious with my fertilising regime as well 🙂

  3. Hi Neil and Mike, great tree Neil. With Callistemon you can cut branches hard after flowering and between then and March the new shoots should / can still be pinched and pruned. The cut off is no later than March and then aftert which DO not pinch or trim any growth. This will allow setting of all flower buds coming into Spring. Leaving long shoots will not give a display with the Most flowers available. Hope you can get some great flowers shows nwext Spring. Thanks and cheers, regards Craig.

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