A few members of my gardening club have installed nesting blocks for native bees in their gardens. This sounds like something that would help me with more sustainable
gardening practices. Can you offer advice?
— Noel Judson, Chicago
Thank you for this question, Noel. Installing a nesting block is a great way to help attract native bees to pollinate your garden. This is something you can buy or make yourself. Rot-resistant cedar and redwood are excellent materials for nesting blocks, but recycling-minded gardeners can reuse whatever wood they have. Be sure the wood has not been treated with chemicals. Untreated wood is readily available at big-box stores and lumberyards. Ask them to cut blocks to length with an angle at one end for the roof. Bees are not fussy and simply want shelter from the elements and a suitable place to nest. Start with a block of wood that is 4 inches wide, 6 inches deep and about 1 foot tall. You can also glue together several foot-long pieces of 4- by 6-inch boards with predrilled holes.
Drill different-sized holes in each block to encourage different-sized bees to nest. Bee diversity is good for plants. Alternate rows of holes that are 5/16 of an inch in diameter with rows that are 3/8 of an inch in diameter for the best results. Alternatively, you can make more than one nesting block with different-sized holes in each to attract different kinds of bees. All of the holes should be about 5 inches long or deep in the block. Install on an overhanging roof to help protect the nest. The Garden’s website has additional information on making homemade bee nests.
Install bee nesting blocks near flowers or trees in a sunny location that is protected from wind. The block should be placed between 3 and 15 feet off the ground. Place the nesting block near eye level (or at different eye levels if you are installing more than one) to make it easier to monitor bee activity. After a few years, redrill the holes and soak the nesting block for 30 minutes in a solution of water and bleach. Rehang the bee nesting block after it has dried.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.
