Mine just started opening its flowers, and the buds have been there for at least 6 weeks - I first noticed them around Xmas. We had very cool weather in January, with just a few short warm-ups.
If your greenhouse is getting pretty cool at night still, I'd not worry, just keep them well watered. Once it warms up the flowers will shoot up and open. Pretty little white flowers, sometimes scented too! (I'm not getting any scent yet on mine . . .
) That stem laying on the table at left is broken, but I'm waiting to separate it and hopefully root it when the flower finishes.