About a year ago we were given a small aluminium greenhouse by new neighbours who preferred it to go for safety reasons, having young children and because of future house extension plans.
However the biggest part of the experiment was to plant our potted Dahlia imperialis var. album in the ground, with a view of removing panes of glass when it grew too tall.
It grew rapidly in the spring, and the glass needed removing by the third week in May. It had been joined by the commoner pink form, bought at the Plant Heritage spring plant fair at Hyde Hall. I told the seller of our greenhouse idea, and he warned me it was likely to fail as the plant responds to day length and short of covering it with blackout material it would flower at the same time as without the greenhouse.
I suspected that he was correct but we went ahead with the experiment anyway.
The original white flowered plant grew four stems, whilst the new one grew one. All grew large producing dense canopies of leaves, to the detriment of all the other inhabitants of the greenhouse.
The remaining large stem produced a number of long side branches with many flower buds at the ends