A bee hotel is one of the highest-impact projects you can build for a small garden, balcony, or raised-bed plot. The bees it houses are not the honeybees you picture in a hive. They are solitary species like mason bees and leafcutter bees that nest alone in narrow tunnels, do not swarm, almost never sting, and out-pollinate honeybees per individual by a wide margin. A single female mason bee can do the pollination work of dozens of honeybees because she carries pollen dry on her belly, dropping it generously as she moves from bloom to bloom. Give her a row of clean, correctly sized tunnels and she will fill your fruit trees, squash, and berry canes with fruit.
Part of our Flowers & Perennials guide →
In this guide
The catch is that most bee hotels sold in garden centers and built from online plans are actively harmful. They use the wrong tube diameters, trap moisture, can never be cleaned, and become disease factories that kill more bees than they raise. This guide shows you how to build a hotel that genuinely helps. We will cover the materials, the exact dimensions that matter, the assembly steps, where to mount it, and the maintenance that separates a thriving nest from a mite-infested death trap. If you are already working to attract bees to your garden with the right flowers, a good hotel is the natural next step.
Key Takeaways
- Solitary mason and leafcutter bees need tunnels 4–10 mm wide and roughly 15 cm (6 in) deep, closed at the back.
- Use natural materials only: hollow plant stems, paper liners, or drilled untreated hardwood. Never use plastic, glass, or bamboo that splinters.
- Mount the hotel facing morning sun (south or southeast), 1–1.5 m off the ground, fixed firmly so it does not swing.
- Add a roof overhang to keep rain out, and a back wall so tunnels are dead-ended.
- Clean or replace liners every year. Uncleaned hotels breed parasitic mites and fungal disease that wipe out the next generation.
- Avoid the classic garden-center “bug hotel” with wide tubes, pinecones, and varnished wood — it is decorative, not functional.
Which Bees You Are Building For
Knowing your tenants drives every design choice. The two groups that readily use tunnel-style hotels in temperate North America are mason bees and leafcutter bees, and they are active in different seasons.
Mason bees (Osmia spp.) are early-spring fliers, emerging when fruit trees and early perennials bloom, often March through May depending on your zone. They seal their nest cells with mud, which is why they are called mason bees. They prefer tunnels around 6–8 mm in diameter. Provide a patch of bare, damp clay-rich soil nearby so the females have mud to build with — without it, they cannot complete their cells.
Leafcutter bees (Megachile spp.) are summer bees, active roughly June through August. They cut neat semicircles from leaves — roses, lilac, and redbud are favorites — and use the pieces to wrap each egg cell. They like slightly narrower tunnels, around 5–7 mm. The leaf damage looks alarming but is purely cosmetic and harms no plant.
By offering a range of tunnel sizes from 4 to 10 mm, you accommodate both groups plus a handful of smaller solitary species. Tunnels wider than 10 mm invite wasps and are mostly ignored by the bees you want.
Materials List
- Untreated hardwood or softwood block — at least 15 cm (6 in) deep front to back, any width. Oak, beech, or pine. Never pressure-treated or painted lumber; the chemicals are toxic to larvae.
- Hollow plant stems — cut dried, hollow or pithy stems such as common reed (Phragmites), teasel, sunflower, raspberry cane, or elder. Aim for inner diameters of 4–10 mm.
- Paper nesting tubes or cardboard liners (optional but recommended) — they slide inside drilled holes and make annual cleaning trivial.
- A wooden box or frame to hold the tubes — scrap fence board or untreated ply works.
- A sloped roof piece with a 5 cm (2 in) overhang at the front.
- A solid back panel so every tunnel is closed at the rear.
- Brad nails or exterior wood screws and a little waterproof wood glue.
- Drill bits in 4, 6, 8, and 10 mm; a brad-point bit gives the cleanest holes.
- Secateurs or a fine saw for cutting stems to length, and fine sandpaper.
Step-by-Step: Building the Hotel
Step 1 — Build the box
Construct a simple open-fronted box from untreated wood: think of a deep picture frame with a solid back. The internal depth should be at least 15 cm so tunnels are long enough — female bees lay female (fertilized) eggs at the back and male eggs near the front, and a tunnel that is too shallow produces almost all males, which does nothing for next year’s population. Size the box to whatever scale suits your space; a 20 by 20 cm front opening is plenty for a first build. Keep it modest. Several small hotels spread around the garden are far healthier than one giant block, because concentrated nests attract concentrated parasites.
Step 2 — Add the roof
Fit a sloping roof that overhangs the front opening by at least 5 cm. Rain is the enemy: wet tunnels grow mold and rot the developing larvae. The overhang shades the entrances during the hottest part of the afternoon while still letting morning sun warm them. Angle the roof so water runs off the back, not down over the tube openings.
Step 3 — Prepare the tunnels
You have two good options, and combining them is ideal.
Hollow stems: Cut your dried stems so that each piece has a natural node (the closed joint) at the back end, leaving the tunnel sealed at the rear and open at the front. Trim them to about 15 cm long. Cut cleanly just past a node so the back is dead-ended. Sand or singe the cut front edge smooth — a ragged opening will tear a female’s wings. Discard any stem that splits lengthwise.
Drilled blocks: Take a solid untreated block and drill horizontal holes in a mix of 4, 6, 8, and 10 mm bits. Drill as deep as your bit allows, ideally 12–15 cm, but never all the way through — the back must stay closed. Space holes about 2 cm apart. Drill slowly and clear the bit often so the inside walls are smooth, then blow out the sawdust. Rough interior walls snag bees and harbor mites.
Step 4 — Insert paper liners (strongly recommended)
Slide a paper or cardboard tube into each drilled hole. Liners are the single best upgrade you can make. At the end of the season you simply pull out the old liners with their cocoons, harvest or protect the cocoons, and drop in fresh liners — the equivalent of changing the bedding. Without liners, drilled wood holes accumulate mites and fungal spores you can never fully scrub out.
Step 5 — Pack and finish
Pack the stems or lined block snugly into the box so nothing rattles loose in wind. Mix the diameters across the face. The finished hotel should present a tidy honeycomb of openings, all dead-ended at the back, all sheltered by the roof. Do not varnish, paint, or seal the wood — leave it bare so it breathes and stays non-toxic. A bit of weathering is exactly what the bees want.
Where and How to Site It
Placement makes or breaks occupancy. Solitary bees are cold-blooded and need to warm up before they can fly, so morning sun is non-negotiable.
- Face it toward morning sun — south or southeast in the Northern Hemisphere. The bees need early warmth to become active.
- Mount it 1 to 1.5 m (3–5 ft) off the ground, above the splash zone and out of easy reach of predators.
- Fix it rigidly. A swinging hotel will not be colonized — never hang one from a string or wire. Screw it flat to a fence, wall, post, or shed.
- Shelter from prevailing wind and driving rain. Under an eave or against a warm wall is perfect.
- Keep flowers and a mud source within ~100 m. Mason bees need damp clay-rich soil for their cell walls; leave a small bare patch and keep it slightly moist.
Put the hotel up in late winter or very early spring, before the first mason bees emerge, so it is ready when they start scouting. Pairing the hotel with nearby blooms gives new arrivals a reason to stay; many of the same native plants that draw butterflies to your garden also feed solitary bees.
Cleaning and Yearly Maintenance
Maintenance is the part nearly everyone skips, and it is the part that matters most. A neglected bee hotel becomes a reservoir for pollen mites, parasitic wasps, and chalkbrood fungus. Each year these parasites multiply, and within two or three seasons a once-busy hotel kills more bees than it raises.
The simplest routine: in autumn, after the new generation has sealed itself into cocoons, move the filled tubes or liners into a cool, dry, predator-proof container — an unheated shed or a ventilated box in a cold garage works. This protects them from woodpeckers and weather over winter. In late winter, set the cocoons back out near a clean hotel so emerging bees re-colonize fresh tunnels rather than the old contaminated ones.
If you are using paper liners, replace them every year — never reuse a liner. With drilled blocks and no liners, you should retire the whole block every two years at most, because you cannot disinfect the interior tunnels. Some keepers gently rinse harvested mason-bee cocoons in cool water with a drop of bleach to knock back mites, then air-dry them; this is optional but effective in heavily infested areas. The golden rule is simple: every tunnel a bee uses should be cleaned or replaced before another bee uses it.
Harmful Designs to Avoid
The decorative “insect hotels” sold in big-box stores are mostly the things to avoid in one box. Steer clear of these:
- Plastic or glass tubes. They do not breathe, so condensation collects inside and drowns or molds the larvae. Natural materials only.
- Tunnels that are too wide (over 10 mm) or too short (under 10 cm). Wide tubes attract wasps; short tubes produce only male bees and crash the population.
- Open-ended tubes. Every tunnel must be closed at the back. A through-hole is a wind tunnel no bee will use.
- Splintered bamboo or rough-cut stems. Sharp edges shred wings. Always sand or singe the openings.
- Varnished, painted, or pressure-treated wood. The finishes and preservatives are toxic to developing larvae.
- Giant multi-story “grand hotels.” Massive nests concentrate parasites and disease. Several small, cleanable units beat one huge block every time.
- Pinecone-and-twig filler. It looks charming and houses nothing useful — it is purely ornamental.
Build small, build clean, build with natural materials, and commit to the yearly cleaning. Do that and your hotel will hum with mason bees in spring and leafcutters in summer, and your fruit set will show the difference. For more small-space wildlife projects, browse the Urban Gardening hub.
Frequently Asked Questions
Will the bees in my bee hotel sting me?
Almost never. Mason and leafcutter bees are solitary species with no hive or queen to defend, so they are extremely docile. Males have no stinger at all, and females will only sting if you squeeze one directly. You can stand and watch a busy hotel from inches away in complete safety.
How long until bees move in?
If you site it correctly — morning sun, firmly mounted, flowers nearby — mason bees often investigate within the first spring, though full occupancy can take a season or two as a local population builds. Putting the hotel up before bees emerge in early spring gives you the best chance the first year.
What diameter holes should I drill?
Offer a range from 4 to 10 mm. Most mason bees prefer 6–8 mm and leafcutters 5–7 mm; the smaller and larger sizes serve other solitary species. Keep tunnels around 15 cm deep and always closed at the back. Avoid holes wider than 10 mm, which mostly attract wasps.
Do I really need to clean it every year?
Yes. Cleaning or replacing liners annually is the difference between a healthy hotel and a parasite trap. Pollen mites and chalkbrood fungus accumulate fast; within two or three uncleaned seasons a hotel kills more bees than it raises. Paper liners make this a two-minute job.
Can I just buy a bee hotel instead of building one?
You can, but inspect it first. Most decorative store-bought “bug hotels” use plastic tubes, over-wide holes, and pinecone filler that bees ignore or that breed disease. Look for natural stems or replaceable paper liners, tunnels in the 4–10 mm range, a back wall, and a roof. If it has those, it will work; if not, build your own.