Beneficial insects such as hoverflies are important for a biodiverse garden. They help with pollination and pest control, and can be very beautiful to admire. If I had to single out one group of flowers to lure in beneficial insect life, it would be hardy annuals. These easily grown flowers are nectar-rich because they need to be pollinated in order to set seed to survive. Calendula (pot marigold), blue cornflower (Centaurea cyanus), annual scabious and larkspur seeds can be scattered straight into well-raked soil from mid-April until July and within six weeks these flowers will be pulling in every bee.
Attracting hoverflies to control aphids
One of the most useful insects for the gardener is the hoverfly. Hoverflies float over the garden in warm weather, drinking nectar and ingesting pollen. They lay single eggs, shaped like oval rugby balls, close to colonies of aphids.
The transparent hoverfly larvae, which could easily be mistaken for bird droppings at a casual glance, consume large numbers of aphids before pupating.
Hoverflies have strict preferences, however. Firstly they like tiny flowers because they have small mouths. Members of the cow parsley family (also known as umbellifers) are perfect for them. These include astrantias and eryngiums. The acid-yellow flowers of the biennial Smyrnium perfoliatum, the perennial cow parsley (Chaerophyllum hirsutum 'Roseum' and the dainty Anthriscus sylvestris 'Raven's Wing' are perfect. But they are also attracted to orange and bright-yellow flowers.
My three favourite plants for hoverflies
Orlaya grandiflora has finely cut glaucous foliage and produces umbels of tiny pure-white flowers surrounded by showier white petals. (Thompson & Morgan)
Ammi visnaga forms flat, dense heads of green-white flowers set against ferny, green foliage. (Thompson & Morgan)
Bupleurum griffithii 'Decor' This lime-green annual has a boss of tiny flowers surrounded by a ruff of everlasting, zigzagged bracts. (Chiltern Seeds)
Calendula officinalis 'Indian Prince': a dark-centred orange pot marigold. Hardy ( Mr Fothergill’s)
Tagetes patula 'Bo Jangle': the only tall African Marigold variety to produce a mixture of doubles, semi-doubles and singles in shades of mahogany and orange. Half hardy (Suttons)
Tagetes patula 'Scarlet Sophie': This semi-double French marigold isn’t as petal-packed as many so hoverflies can still reach the middle. Half hardy (Thompson & Morgan)
Add a perennial backbone
The dark sedum 'Purple Emperor' and cone flowers (Echinacea purpurea) can also be woven along the border to provide a permanent backbone. Agastaches and achilleas are also highly popular and all four will provide stiff winter seed-heads.
Practical tips for sowing a hoverfly strip
- Loosely dig over a sunny strip.
- Plant your perennials and sprinkle the seeds of Calendula 'Indian Prince' into the ground - ideally between mid-March and mid-April.
- Sow seeds of all all three umbellifers in late March under glass and prick out one seedling and place into a three-inch round pot. Plant them outside from early to mid-May.
- Sow Tagetes patula 'Bo Jangle' and 'Scarlet Sophie' in early April (under glass) and prick out into seed trays. Plant out from mid-May onwards - to avoid frost damage.
NB - You can easily collect and keep seeds from all calendulas, Bupleurum griffithii 'Decor' and Orlaya grandiflora.
Read Val Bourne's tips for a natural, organic garden, or read more of our garden wildlife guides
Val Bourne is the author of The Living Jigsaw: How to Cultivate a Healthy Garden Ecology