Make Your Garden Bee-Safe

Bee hives on a farm in Washington state help pollinate crops. You can build nests to help attract bees to your garden.

Bees across the country are disappearing due to a mysterious condition know as Colony Collapse Disorder, threatening agriculture and many of your favorite foods.

But you can help keep these important pollinators healthy by attracting them to your garden.

Here are some helpful tips for gardeners:

Include a wide variety of plants

Ideally, they should bloom from early spring into late fall or, if possible, for the entire year. If you choose plants with a variety of shapes and colors, you will be more likely to attract different types of pollinators. Planting in clusters will make them easier to locate.

Plant native species

Local plants are four times more likely to attract pollinators than exotic species. See the list of suggested native plants on the right.

Avoid using pesticides

There are many natural ways to control pests in your garden. If you must use pesticides, read the labels carefully in order to avoid spraying chemicals that are highly toxic to bees, such as most neonicotinoid pesticides. Be sure to spray your plants after dusk, when pollinators are least active. You should also be wary of using multiple pesticides at once. Many active ingredients are more toxic when used in combination with other pesticides.

Here are some of the pesticides most toxic to bees and what they’re commonly used for:

• Clothianidin: Corn, canola
• Dinotefuran: Cabbage, bell peppers, cotton, grapes, melons
• Imidacloprid: Cabbage, pumpkins, cotton, blueberries, citrus, grapes, melons
• Thiamethoxam: Bell peppers, cotton, cantaloupes, cherries, pears, strawberries, watermelons

Create the right environment

Providing shallow pools of water will attract bees and keep them healthy. Another great way to help bees thrive is to provide a variety of nesting habitats. The following instructions will tell you how to build nests for three different types of bees.

Building Nests for Bees

Wood-Nesting and Cavity-Nesting Bees

About 30 percent of native bee species make their nests in old beetle tunnels, in snags (dead standing trees) or in similar locations. If possible, retain snags to encourage nesting. Where you can’t, make some nesting blocks. Here’s how:

Nesting Blocks

• Drill nesting holes 3/32 and 3/8 of an inch in diameter, at approximate 3/4-inch centers, into the side of a block of preservative-free lumber.
• The holes should be smooth inside and closed at one end.
• Holes less than ¼ inches in diameter should be 3 to 4 inches deep. For holes ¼ of an inch or larger, a 5- to 6-inch depth is best.

Adobe Blocks

• In desert areas, adobe blocks can be drilled with holes as outlined above.

Logs and Snags

• Place logs or old stumps in sunny areas; those with beetle tunnels are ideal.
• Plant a few logs or stumps upright, like dead trees, to ensure that some deadwood habitat stays dry.
• On the southeast side of each log, drill a range of holes, as outlined above.

Stem or Tube Bundles

• Use plants with naturally hollow stems like teasel, bamboo and reeds.
• Cut the stems into 6- to 8-inch lengths. Be careful to cut the stems close to a stem node to create a tube with one end closed.
• Tie 15 to 20 stem pieces into a bundle (with the closed ends together). Or make a wooden frame to hold as many stems as you like.
• Paper tubes can be used, as well. Just make sure they stay dry.
• Make sure the stems or tubes are horizontal.

Location of the nesting sites is important. These nests should be placed where they are sheltered from the worst of the weather, with entrances facing toward the east or southeast to get the morning sun. The nests can be any height from the ground, but between three and six feet is convenient. Put them on a building, fence, or stake, or place them in a tree. Fix them firmly so that they do not shake in the wind.

Ground-Nesting Bees

Most native bees -- about 70 percent of species -- nest in the ground and need access to the soil surface to dig their nest. Each female excavates her own nest tunnel and brood cells and stocks the cells with nectar and pollen.

Bare Ground

• Clear the vegetation from small patches of level or sloping ground and gently compact the soil surface.
• The patches can be from a few inches to a few feet across but should be well drained and in an open, sunny place. A south-facing slope can be a good location.
• Different ground conditions -- from vertical banks to flat ground -- will draw different bee species, so create nesting patches in different areas to maximize the nesting opportunities.

Sand Pits and Piles

• In a sunny, well-drained spot, dig a pit about 2 feet deep and fill it with a mixture of pale-colored, fine-grained sand and loam.
• Where soils do not drain well, a pile of the sand/loam mixture can help, or you can make a raised bed.
• If space is limited, you can fill planter boxes with the sand loam mixture.

Bumble Bees

Unlike the nests built for solitary bees, there are no strict size requirements for bumble bee nests. Any hole large enough for a small colony will be OK. After emerging from hibernation, a bumble bee queen will hunt for a dry, warm cavity in which to start her colony. In natural conditions, most bumble bees nest in abandoned mouse holes in the ground or under grass tussocks. Where you can, keep patches of rough grass. Where you can’t, consider building a nest box or two.

Nest Box

• Use a simple wooden box, with internal dimensions of about 7 by 7 by 7 inches, made from preservative-free lumber.
• Drill a few ventilation holes near the top (cover with door screen to deter ants) and some drainage holes in the bottom.
• Make an entrance tunnel from ¾-inch plastic pipe, marked on the outside with a contrasting color.
• Fill the box with soft shoe bedding material, such as upholsterer’s cotton or short lengths of unraveled, soft string.
• The box must be weather tight; the larvae may become cold and mold and fungus will grow in a damp nest.
• Place the box in an undisturbed site, in partial or full shade, where there is no risk of flooding.
• The box should be on or just under the ground. If you bury it, extend the entrance tube so that it gently slopes up to the surface.
• Put your nesting box out when you first notice bumble bees in the spring, or when the first willows or other flowers are blooming.
• Be patient. There is no guarantee that bees will use your box. Only about one in four boxes gets occupied. If it has no inhabitants by late July, put the nesting box into storage until next spring.

Guide adapted from the Xerces Society