Wildflower Meadows and Beneficial Insects: Gardening for Biodiversity
A wildflower meadow and a handful of simple habits are enough to turn a garden into a refuge for beneficial insects: ladybirds, lacewings and hoverflies devour aphids, while wild bees, bumblebees and butterflies handle pollination. Belgium is home to around 400 species of wild bee, 30 to 40 percent of which are now under threat, chiefly because meadows are disappearing and pesticides remain in use. Three levers really matter for bringing them back: sowing a wildflower meadow with native seed, mowing late and removing the cuttings, and setting up a well positioned insect hotel while banning chemical treatments.
Beneficial Insects: Who They Are and What They Do in the Garden
A beneficial insect does the gardener a favour without needing to be paid for it: it either pollinates flowers or hunts down pests. Pollinators, wild bees, bumblebees, adult hoverflies and butterflies, carry pollen from flower to flower. Belgium hosts around 400 species of wild bee, which do most of the work in a private garden; Wallonia’s public service (SPW) notes that roughly 75 percent of crops depend at least partly on this pollination.
Predators, for their part, keep pests in check without any chemical intervention. The ladybird larva devours several hundred aphids before turning into an adult. The lacewing larva, nicknamed the aphid lion for its curved jaws, eats between 200 and 500 during its development; the adult feeds only on nectar and pollen, becoming a pollinator in its own right. The hoverfly larva, spindle shaped and legless, gulps down between 400 and 900 aphids in two to three weeks. These three allies alone are often enough to contain an infestation without any treatment at all.
Three Habits That Attract Them: A Hotel, a Fallow Patch and Zero Pesticides
The most effective habit, and the cheapest, is to stop using pesticides, including so called natural products like nettle manure sprayed over a wide area, which also kill hoverfly and lacewing larvae. Adalia, a non profit based in Namur that grew out of the 2001 campaign Ladybirds Rather Than Pesticides, runs a network of nurseries certified Gardening Without Pesticides and helps Walloon municipalities move toward zero pesticide use.
Second habit: leave one part of the garden unmown for the whole season, even just a square metre against a hedge. Tall grass shelters caterpillars, hollow stems house larvae, and self seeded flowers like dandelion feed the first foragers of the year. Third habit: put up an insect hotel, facing due south or south east for at least six hours of sun, sheltered from wind and rain, fixed firmly at about chest height, and filled with hollow bamboo or pruned elder stems and logs drilled with holes two to ten millimetres wide: each diameter attracts a different species of solitary bee. The Walloon Region’s Maya Plan, its pollinator protection programme, recommends combining all three habits.
Sowing a Wildflower Meadow: Poor Soil and Native Seed
A wildflower meadow isn’t planted into an existing lawn, it’s sown onto depleted soil. Wildflowers such as cornflower, poppy and knapweed are suited to poor ground and get smothered by grasses the moment fertiliser or compost is added. If the plot is rich, impoverish it by mowing it several times and removing the cuttings, or by working a little sand into the topsoil before sowing. Cultivate only the top two to three centimetres, without digging deep, so as not to bring a buried stock of weed seeds back to the surface.
Two sowing windows work well: late March to early May, or late August to early October, which produces a fuller bloom the following spring and copes better with the dry springs Belgium has seen in recent years. Allow around five grams of seed per square metre. Belgian broadcaster RTBF has reported on the trap set by some cut price seed packets, made up of showy horticultural varieties, cornflowers and cosmos bred for large blooms, that catch an insect’s eye without offering any usable nectar. A Walloon seed producer such as Ecosem offers seed of genuinely native, local stock, which is far more useful to wildlife.
Late Mowing: The Habit That Decides Everything
A wildflower meadow is mown, not cut like a lawn. The basic rule recommended by the Belgian nature organisation Natagora for a private garden is a single mow a year, in autumn, once the late flowering plants have had time to set seed. A meadow richer in perennial grasses can take two cuts, one in June after the early species have flowered and a second in September, which favours floral diversity over time. Always remove the cuttings: leaving them where they fall enriches the soil with nitrogen, to the detriment of the flowers.
Always leave a portion unmown, a quarter to a third of the area, rotating it from one year to the next: this is the refuge where caterpillars, eggs and larvae overwinter. Wallonia has applied this same principle on a large scale since 1995: the Roadside Verges convention, signed by all 262 Walloon municipalities, requires mowing only after 1 August north of the Sambre Meuse divide and after 1 September south of it, across more than 17,000 kilometres of verges. More than 700 plant species, half of Wallonia’s flora, have been recorded there since.
Which Flowers to Add, Season After Season
The wildflower meadow feeds insects mainly in summer, but they need resources from the first mild spell in February right through to the October frosts. Round it out with beds that stagger the flowering. As winter ends, crocus and hazel provide the first pollen for the queen bumblebees and solitary bees that emerge early, sometimes as soon as February in Belgium. Through spring and summer, rely on nectar rich herbs: thyme, oregano, sage, rosemary and lavender draw a steady stream of bees, bumblebees and butterflies, and lemon balm, nicknamed bee balm, rounds out the mix.
Buddleia, the butterfly bush, lives up to its name: its scented flower spikes can gather dozens of butterflies in a single sunny afternoon. Nasturtium attracts both aphids and hoverflies at once, which makes it a useful trap plant near the vegetable patch. Marguerite daisies and coneflower give hoverflies easy access to nectar, while petunia and verbena keep the offer going into late summer. Elder and honeysuckle provide flowers for foragers and berries for birds. Staggering the blooms, from crocus to elder, avoids the gaps that send beneficial insects looking elsewhere.
The care sheets to read next
Every plant mentioned has its full sheet: watering, light, soil, pests and a month-by-month calendar.
Lavender
Lavandula angustifolia
True lavender (Lavandula angustifolia) is a hardy Mediterranean plant that scents the air and draws bees all summer…
Butterfly bush
Buddleja davidii
Buddleia (Buddleja davidii), better known as the butterfly bush, is a nearly indestructible shrub that has taken over…
Coneflower
Echinacea purpurea
Coneflower (Echinacea purpurea) is a tall, sturdy perennial from the prairies of North America, recognisable by its…
Oxeye Daisy
Leucanthemum vulgare
The oxeye daisy (Leucanthemum vulgare) is that white flower with a yellow centre that pops up on its own in our…
Sage
Salvia officinalis
Common sage (Salvia officinalis) is a small aromatic shrub with evergreen grey-green foliage, originating from the dry…
Oregano
Origanum vulgare
Oregano (Origanum vulgare) is a tough, perennial herb built for sun and dry soils. In Belgium, here is the good news:…
Thyme
Thymus vulgaris
Thyme (Thymus vulgaris) is a small Mediterranean subshrub with woody stems and a powerful fragrance. Used to the dry,…
Rosemary
Salvia rosmarinus
Rosemary (Salvia rosmarinus, long known as Rosmarinus officinalis) is an evergreen Mediterranean shrub with needle-like…
Nasturtium
Tropaeolum majus
The nasturtium (Tropaeolum majus) is an annual native to the Andean highlands of Peru and Colombia that has become an…
Petunia
Petunia
Petunia (genus Petunia), also sold under the name Surfinia for its trailing varieties, is the queen of Belgian window…
Elder
Sambucus nigra
Elder (Sambucus nigra) is a large native shrub that grows wild in hedgerows, along footpaths and on waste ground right…
Hazel
Corylus avellana
The hazel (Corylus avellana) is a native shrub of our countryside, found for as long as anyone can remember in the…
Honeysuckle
Lonicera
Honeysuckle (Lonicera) is a familiar plant in our hedgerows and gardens, known for its very fragrant tubular flowers…
Lemon balm
Melissa officinalis
Lemon balm (Melissa officinalis) is a hardy perennial with crinkled foliage that gives off a lemon scent the moment you…
Lemon verbena
Aloysia citriodora
Lemon verbena (Aloysia citriodora) is a shrub whose leaves give off a clean, intense lemon scent, the one in an evening…
Crocus
Crocus
Crocus is the very first splash of colour in a Belgian garden as winter loosens its grip. In the Herve region, it is…
Frequently asked questions
When should you sow a wildflower meadow in Belgium for the best bloom?
Two periods work well: late March to early May, or late August to early October. Autumn sowing is now often preferred, since it produces a fuller bloom by the following spring and copes better with the dry springs Belgium has seen in recent years. Allow around five grams of seed per square metre on soil that has already been impoverished.
How many times a year should a wildflower meadow be mown?
A simple wildflower meadow is mown just once, in autumn, once the late flowering plants have set seed. A meadow richer in perennial grasses can take two mowings, one in June and one in September, which strengthens floral diversity over time. Either way, remove the cut hay and always leave a portion of the area unmown as a refuge.
Which beneficial insects control aphids in the garden?
Three main ones: the ladybird, the lacewing, whose larva is nicknamed the aphid lion, and the hoverfly. A lacewing larva eats between 200 and 500 aphids during its development, a hoverfly larva between 400 and 900. Attracting these allies is enough, in most gardens, to avoid any chemical treatment against aphids.
How do you set up an effective insect hotel for solitary bees?
Face it due south or south east, so it gets at least six hours of sun and stays sheltered from wind and driving rain. Fix it firmly in place, at about chest height, and fill it with hollow bamboo or elder stems, logs drilled with holes two to ten millimetres wide, and hollow bricks: each diameter houses a different species of solitary bee.
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