In my worklife, answering various gardening questions, one thing I can be certain of is that every summer there will be several queries from astonished people with a dahlia plant that has suddenly produced a flower of a different colour, or, more often, with some ‘petals’ of a different colour. These questions are as certain as those about thorn apples (datura), Canadian fleabane and teasels.

Well this year it has happened to me.

I grow about 20 plants for cut flowers and they are not especially fine. I chose them because they have small flowers, facing upwards, ideal for bunches and they are really rather boring. I bought them last year and overwintered the tubers and lost a few but divided what survived – quicker than cuttings – and have five cvs including one I didn’t order but was given as a freebie. It is ‘X factor’, short with huge flowers and not what I need at all. I cut what it produces but even when priced at 3euro a bunch of huge red, white-striped blooms I end up composting them.

But one plant with pink flowers has produced a cherry-red flower and an adjacent one has some red ‘petals’. Now these ‘sports’ are not that uncommon and, in theory can be saved and propagated and are one way that new cvs are produced (look at all the variations now available of ‘Cafe au Lait’) but it might be a challenge to root these aerial stems which are hollow.

What is curious is that this flower had problems from the start. A few weeks ago I noticed that it was starting to be colonised by blackfly. Now this year has nor been too bad for aphids, maybe because earlier in the summer I wasted lots of time ‘saving’ every ladybird I found when weeding and making sure it did not get buried in the compost. But as the dark mass of aphids started to expand I noticed a few gaps and found a lacewing larvae (oh how I wish I had taken a photo) and within a few days all the blackfly were gone. Only one stem was affected. Lacewings are those amazingly graceful little green-bodied flying insects with golden eyes and their larvae are voracious aphid eaters.

So is it a coincidence that this bud, which must have had some sap sucked from it during development, has produced a flower in a different colour? The illogical, unscientific side of my brain will blame the colour change on the aphids but it cannot be. And the fact that the neighbouring flower has hints of the same colour change suggests that it is truly a mutation.

I disbud all the dahlias so I have longer stems and (slightly) larger flowers, ideal for picking, but maybe I will leave this stem and see if subsequent flowers show the same colouring. And then I will decide if I want to try to ‘fix’ it.

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