Germany is home to roughly 600 species of wild bee, and most of them you would never recognise as bees at all. Many are tiny, and instead of yellow and black they wear rust red, metallic green or plain grey. They do not live in a colony; they live alone. Each female is queen and worker in one: she builds the brood cells, gathers the pollen, lays the eggs and dies long before her offspring hatch. These quiet loners often pollinate your garden more reliably than the honeybee, and many of them have become rare.
The best-known piece of advice goes: put up a bug hotel. That is well meant, but it is only a small part of the story. The great majority of wild bees never move into tubes at all; they nest in the ground. If you genuinely want to help wild bees, think in three building blocks: bare soil to nest in, a nesting aid for the tube dwellers, and above all forage, meaning pollen and nectar from the first warm day in February right through to October.
First understand how wild bees live
Before you buy or build anything, it pays to look at the biology. Almost all wild bees are solitary bees. A female hatches in spring, mates, looks for a nest site and lays her entire brood within a few weeks. Into each brood cell she packs a store of pollen and nectar, lays an egg on it and walls the cell up. Once the store for all the cells is laid in, the female's life is usually over. Her offspring develop safely inside the nest, overwinter there and hatch the following year.
Everything else follows from that life cycle. The bees need nest site and food close together, because an exhausted female does not fly for kilometres. Many species are on the wing for only a few weeks a year; if nothing suitable is in flower during that time, a whole generation is lost. And a large share are specialised on particular plant families. The harebell scissor bee collects pollen almost only from bellflowers. No bellflower, no scissor bee.
A bug hotel is a bedroom. Without a kitchen within a few hundred metres it stays empty.
The core idea of this article
Building block 1: Bare soil, the overlooked nest site
Around three quarters of native wild bee species nest in the ground. Mining bees, furrow bees, pantaloon bees, plasterer bees: they all dig tunnels into the earth and lay their brood cells there. What they need for it is astonishingly simple: an open, unvegetated, sunny patch of soil, ideally slightly sloping and sandy. In tidy gardens that has become hard to find, because lawn, bark mulch, weed fabric or paving cover everything.
Vertical surfaces count too: an open, sun-facing loam wall, an unmortared dry-stone wall, a broken edge at the border of a bed. Wherever the soil simply stays bare, resist the urge to plant it up or mulch it. Bare earth is not a failing; it is habitat.
A second, often forgotten nest type is pithy and hollow stems. Many species nest in the dead stems of bramble, mullein, mugwort, teasel or elder. That is why the most important autumn advice is: do not cut perennials down to the ground and do not clear them away. Leave the stems standing over winter, and when you do cut in spring, leave 30 to 60 cm of upright stubs. The brood overwinters inside those stubs, and in summer fresh females move into the newly broken ends.
Building block 2: Build the nesting aid properly
The classic nesting aid reaches only the tube dwellers: mason bees, yellow-faced bees, resin bees and a few scissor bees. That is a minority of species, but a rewarding one. You can watch these bees nesting right outside your window, and their pollination of fruit is enormous. A single mason bee pollinates many times more blossoms per day than a honeybee.
The problem: most shop-bought bug hotels are poorly made. Pine cones, loose bits of bark and glass tubes are pure decoration. Frayed drill holes injure the wings. Holes in end grain crack and go mouldy. Here is how to build a nesting aid that actually gets used:
Use seasoned hardwood
Drill into the side grain of beech, ash or oak, never into the end grain (the face with the growth rings), or the wood will split. Use well-seasoned wood, not fresh.
Drill clean holes of 2 to 9 mm
The most important range is 3 to 6 mm. Drill 8 to 10 cm deep, but not all the way through. Crucially, the back must be closed, so the tube is a dead end.
Deburr every hole
Run fine sandpaper over the openings until no fibres stick out. Frayed edges injure the wings and are avoided.
Bundle hollow and pithy stems
Reed, bamboo (open at just one node) and pithy stems of bramble or mullein round out the offering. Cut them cleanly and do not crush the ends.
Hang it sunny, dry and steady
Facing south-east or south, with rain protection and without swinging. A wobbling hotel does not get occupied. A height of 1 to 2 m is plenty.
Building block 3: Forage, the true bottleneck
A nest site alone is not enough. The real bottleneck is food, and it has to be continuous. Wild bees are on the wing from the first warm days of February through to October, but not all at once; each species has its own window. A wild-bee-friendly garden therefore blooms without a break, with special attention to two critical phases. The first is early spring: when the first females hatch in March, they go hungry if nothing is in flower. Early willows, crocuses, wild fruit blossom and grape hyacinths are worth their weight in gold then. The second, often overlooked, gap is high summer. After the big flush of May and June, many gardens hit a hole from early July (CW 27). That is exactly when you need late forage plants.
- Very early · February to April
Goat willow, crocus, winter aconite, grape hyacinth, lungwort, wild fruit. Vital for the first generation.
- Spring · April to June
Meadow sage, bugle, dead-nettle, comfrey, wild roses, fruit trees. The great, easy time in the bee year.
- High summer · July to August
Viper's bugloss, bellflowers, mallows, knapweed, wild carrot, hedge woundwort, oregano. This is where you close the forage gap.
- Late · September to October
Asters, stonecrop, ivy, Japanese anemone. Ivy is the last great source of pollen before winter.
When choosing, look for single flowers. Many cultivars with double blooms (petals packed densely instead of visible stamens) offer neither pollen nor nectar; for wild bees they are worthless dummies. And favour native wild plants: a specialised female bee only recognises the pollen source it is adapted to. An exotic carpet of blossom is no use to her.
Viper's bugloss is one of the most valuable forage plants there is. It flowers for weeks right in the middle of the summer gap, refills its nectar continuously, and even has its own specialist in the viper's bugloss mason bee. On poor, sunny banks it self-seeds happily.
Goat willow is the single most important spring shrub for wild bees. Its catkins deliver pollen and nectar exactly when mining bees and bumblebee queens emerge from winter and almost nothing else is in flower. Plant a female goat willow, because only the female shrubs bear the nectar-rich catkins.
Bellflowers are the basis of life for several specialised species, above all the harebell scissor bees, which even sleep inside the flowers. Plant them and you open the door to a whole guild of specialists.
What you should leave undone
Helping wild bees means, to a large extent, doing less. The tidy, close-cropped, sprayed garden is a desert to them. A few deliberate omissions often do more than any purchase.
- Mow less often
Leave a meadow corner standing and mow it only once or twice a year, in stages. In the unmown patch, life blooms and nests.
- Do not strip the autumn bare
Standing perennials, fallen leaves and a brushwood pile are winter quarters and nesting material. Cut stems only late in spring and leave stubs standing.
- Skip insecticides
Insecticides hit wild bees directly, and many products harm beneficial insects too. In a home garden you can almost always manage without.
- Avoid peat and mulch deserts
Bark mulch and weed fabric seal exactly the open soil that ground nesters need. Deliberately leave patches bare.
A realistic plan through the year
You do not have to do it all at once. Helping wild bees is a project of many years, and even the first step brings guests. In early spring (February to April, CW 6 to CW 16) you plant early forage plants and a female goat willow. In spring you hang up the nesting aid before the mason bees start flying in March, and lay out your open sand patch. In May and June you sow a perennial wildflower mix of native species. In high summer you plant against the forage gap with viper's bugloss, bellflowers and late perennials. In autumn you do the most important thing by doing nothing: leave stems, leaves and open patches standing. Next spring the first home-grown bees hatch.
The most wild-bee-friendly garden is rarely the tidiest. It is the most patient.
To take away
Häufige Fragen
Why has my bug hotel stayed empty?
There is usually one of three reasons. First, the nesting aid is badly built: frayed drill holes, holes in end grain, bores that are too wide or go right through, glass tubes or cones as pure decoration. Second, it hangs wrongly, meaning in shade, damp, swinging, or only put up once the mason bees' flight time in March and April was already over. Third, and this is the most common reason, there is no food nearby. A nesting aid without flowering forage within a few hundred metres stays empty. Check the flower supply first, then the quality of the holes, then the location.
Do wild bees really mostly nest in the ground?
Yes. Around three quarters of the roughly 600 native wild bee species nest in the ground. They dig tunnels into open, sunny, often sandy soil, in banks, path edges or bare bed borders. Only a minority, such as mason bees and yellow-faced bees, use cavities and tubes, which is what a classic nesting aid offers. That is why an open, unvegetated patch of soil is often worth more for biodiversity than any shop-bought bee hotel.
Which plants are most valuable for wild bees?
The most valuable are single-flowered, native wild plants that bloom in a staggered sequence across the whole year. Excellent in early spring are goat willow, crocus and wild fruit; in spring meadow sage, bugle and comfrey; in high summer viper's bugloss, bellflowers, mallows and hedge woundwort; and in autumn asters and ivy. Avoid double-flowered cultivars, as they supply neither pollen nor nectar. What matters is less the single superstar plant than an unbroken bloom sequence from February to October.
When do I close the summer forage gap?
The critical summer gap usually begins in early July (CW 27), once the big spring and early-summer flush is over, and runs into late summer (around CW 35). In exactly this window you need late forage plants: viper's bugloss, bellflowers, knapweed, wild carrot, mallows, oregano, hedge woundwort and stonecrop. It is best to plant or sow these already in spring, so that they are in full bloom in July, when the bees need them most urgently.
Are wild bees dangerous if they nest in my garden?
No. Wild bees are practically unwilling to sting and are harmless to people, children and pets. Most species cannot even pierce human skin with their sting, and they are not defending a colony that would make them aggressive. You can watch a mining-bee aggregation in the lawn or a busy nesting aid on the house wall without a second thought. Never treat nest sites with poison; the bees are harmless, useful and strictly protected, and they disappear on their own after their short flight time.
Two neighbouring articles go deeper on individual building blocks. How to build a nesting aid that actually gets occupied is covered in Bug hotels: what actually gets used. And how to keep the bloom sequence unbroken is in A bee pasture all year: closing the forage gap.
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