We've just had the hottest April on record here in the UK - though weather conditions now seem to have settled back to normal for the time of year. As might be expected the pace of Spring growth has been accelerated, so much so that for many plants it's already early summer. I photographed these bearded iris recently - sorry, I don't know the exact cultivar - in full flower at least a month ahead of schedule for South West England.
Bearded iris cultivar
At the same time the last of the narcissus was still giving it's all. Narcissus poeticus is one of the loveliest of the late flowering narcissus and worth a place in any garden. Invariably it flowers in April, no matter how warm or cool the spring has been.
Many spring blooming temperate plants flower in response to two stimuli - day length and temperature. Increasing day length triggers the start of the flowering process - but warmth is needed to accelerate it. A cool spring will always be one with an elongated flowering succession, while the warmth we've had recently will always force growth and flowering, sometimes well out of season. Commercial growers have long known this, using greenhouses to accelerate growth, cool houses to retard it and lighting to manipulate growth initiation. This is one of the compressed years - hasn't it been glorious.