Throw in the trowel Let wild weeds flourish

When digging up dandelions from your lawn, spare a thought for the insects they serve. Invertebrates suffer in rising temperatures and fragmented habitats, and recent studies found that the UK’s flying insect population has declined by up to 60% in the past 20 years.

Keeping some weeds in the garden will at least help their food sources, says Dr Anton Rosenfeld, research manager at the horticultural charity Garden Organic, adding that many weeds are excellent sources of pollen and nectar.

He leads a citizen science garden experiment, asking people to survey weeds and report what types of insects they attract.

“We need to take a different view of weeds,” says Rosenfeld. “We have become too tidy, and there’s a danger we are reducing biodiversity through use of herbicides, especially when people are expecting a lawn just to be grass. It becomes an ecological desert.”

Nectar is a source of energy and sugar for bees, while pollen provides protein – and dandelions come out at the top for producing pollen, he observes, offering the following advice ...

TOP WEEDS

“Clovers in lawns are really important,” says Rosenfeld. “Lawn fertiliser causes grass to dominate, but when you have slightly less fertiliser on the lawn, that favours the clover.” He adds:“The top nectar producers are common ragwort, creeping thistle, spear thistle, dandelion and flatweed, while the top pollen producers are dandelion, rosebay willowherb, corn marigold and flatweed.”

DANDELION

“This is a superweed for insects, because it has such a long flowering period. It blooms early, when there isn’t much other food available for insects, and keeps on going well into autumn.” They are a valuable source of pollen and nectar from March to October, and attract 90 different species of bee, 62 species of hoverfly and 25 species of butterfly, he adds. Dandelions are the fourth highest nectar producers, and can be encouraged by reducing the amount of mowing you do.

NETTLES

Great for herbivorous insects, these provide valuable habitat for butterflies. The red admiral makes “tents”from the leaves and stems.

CLOVERS

The clover bridges an important gap in late summer, producing pollen and nectar when many other species have finished flowering. “White clovers, which are considered weeds, are good for honeybees and bumblebees. Red clover – which is actually pink – has slightly longer flowers and favours the bumblebees,” says Rosenfeld.