I have 4 rhubarb plants, 2 definitely are the same variety, 1 definitely isn’t – it’s Victoria – and the 4th I’m not sure about. This year, the Victoria and one other went straight to flower; the other two are producing good strong stems and haven’t thrown up any flower spikes. They are all together and have been treated exactly the same, with a good manure mulch in autumn and then some more in the early spring. Any idea why this has happened?