Why there are so many dandelions this year - why warm weather has sparked a bumper crop

People in all parts of the country - north, south, east and west - have reported seeing more of the bright yellow flowers and the plants’ shimmering clocks than usual. And your eyes and memory are not deceiving you - there may be a botanical reason for this, says the Royal Horticultural Society’s chief horticulturalist Guy Barter.

While noting that there are “no formal dandelion surveys”, Mr Barter has explained how the climate has contributed to the recent dandelion explosion.

“The colder weather followed by a temperature upswing has led to synchronised flowering as they all bloom at once as temperatures rise significantly,” he said.

Mr Barter pointed out that the RHS says that, if possible, dandelions should be allowed to flower as they are so beneficial to insects. He said: “Dandelions are easily removed from lawns, but the RHS advises that they be spared, if at all possible, at least until after flowering because they are of great value to insects. Ideally winkle them out with a trowel from lawns rather than apply selective herbicides - you can replant them elsewhere if you wish.

“The relatively small areas of high maintenance grass at RHS Wisley are kept dandelion free, but in more extensive lower input areas dandelions are not persecuted, on environmental grounds. Sometimes it is necessary to mow them off when they set seeds to prevent excess spread in the gardens, but usually they are left to their own devices. In unmown swards, of which we have plenty at RHS Wisley, they are kept in check by competition with taller grasses. It is where the grasses are mown that they are more able to multiply.”

And dandelions have another trick up their sleeve, as they can flower in their second year so the wetter weather last year might have helped more seedlings to establish - which are now in bloom. And this in turn could lead to another carpet of yellow in 12 months’ time.

Mr Barter added: “Most dandelion seeds germinate in the first two years after shedding although some will remain dormant and germinate later. Therefore, heavy seed shedding this year might lead to a further flush of dandelions next year. Keep the hoe going and use a coarse mulch to prevent excess in beds and borders and manage lawn so the grass 'squeezes' them to prevent excess numbers.”

The curator of RHS Bridgewater, Marcus Chilton-Jones, added: “Dandelions are beneficial for a wide range of pollinators, including: bees, butterflies, and hover flies – somewhat weirdly, because this is despite the fact that they do not rely on insects to actually be pollinated!’

And Alex Hankey, garden manager, estates and garden services at RHS Wisley said: “Molehills across the garden, and especially in the Orchard at RHS Wisley, are proving to be a perfect patch of disturbed ground for dandelions to seed into and establish amongst the grass.”

The Agriculture and Horticulture Development Board says that dandelions have many micro-species that are difficult to tell apart, and that they are found throughout the British Isles up to 1,220m. They are most frequent in alkaline soils, those with a pH greater than 7.0.

To find out more about dandelions - what they do, how they can help a garden and how to eat them - see the RHS’ information page here.