Welcome to The Bee Gardener, the blog of the UC Davis Häagen-Dazs Honey Bee Haven. The Haven is a half-acre demonstration garden on the UC Davis campus devoted solely to bee pollinator outreach, research, and education. The garden is located just to the east of the Harry H. Laidlaw, Jr. Honey Bee Research Facility and was planted five years ago thanks to a generous gift from Häagen-Dazs™. Free and open to the public every day from dawn to dusk, the garden has inspired and delighted visitors since its grand opening in September 2009.
The garden is unique among public bee gardens in our association with a land grant university and our location within an entomology department; my graduate training was in both horticulture and entomology. It has been my privilege to serve as the garden manager for the past year, and I look forward to continuing to build the Haven and its programs.
Christine Casey, Manager, Häagen-Dazs Honey Bee Haven
Good horticultural practices are important to the success of any garden. In bee gardens, though, we need to do things a bit differently, as some common practices may not be best for the bees. When most of us think of bees and pollination the managed European honey bee, Apis mellifera, comes to mind. But beyond the honey bee are over 1500 species of bees native to California, many of which provide essential pollination services in both wild and agricultural settings. About 70% of these wild bees live in underground nests. This includes the social bumble bees and solitary bees like the long-horned bees (Melissodes spp.), digger bees (Anthophora spp.) and sunflower bees (Svastra obliqua) that are common in urban gardens.
Three important practices that should be adjusted to accommodate ground-nesting bee habitat are mulching, tillage, and sanitation.
Mulch has many benefits in the garden. It retains soil moisture, can protect against soil temperature extremes, and provides valuable habitat for arthropod predators such as ground beetles (family Carabidae). Ground-nesting bees need bare soil to create their nests, however, so bee gardeners should leave some ground uncovered. Visitors to the Honey Bee Haven will notice that the garden has many areas of sparsely-laid mulch to accomplish this. Turf-covered areas are not used for nesting.
Ground-nesting bees have soil preferences that vary by species. This is an area in which very little research has been done, but we do know that undisturbed soil is essential. Tilling the garden destroys underground bee nests and disrupts abandoned rodent burrows that are important bumble bee nesting sites.
Finally, while sanitation is an essential tactic in garden pest management, it’s important to not be too neat. Small clumps of grass or weeds or debris left under shrubs can protect the bumble bee queen as she overwinters in her nest below. Garden visitors will see that we leave some weed growth on the garden edges to provide this type of habitat.
My last post discussed ways to provide habitat for ground-nesting bees, which comprise about 70 percent of California's native bee fauna. And the other 30 percent? They are referred to as cavity-nesting, since they lay their eggs above ground in twigs, abandoned beetle galleries, and other tree cavities. Carpenter bees (Xylocopa spp.) and mason bees (Osmia spp.) are two of the common cavity-nesting bees occurring in urban gardens. As with the ground-nesters, these bees also provide important pollination services. While lifecycles vary by bee species, the general pattern is that eggs are laid in spring and summer with adult bees emerging the next year.
In wild areas where dead or dying trees are not removed, natural habitat for these bees exists. In urban gardens, however, we need to provide the cavities. The good news is that these bees are often flexible in their choice of nesting locations; studies have found that diversity of cavity-nesting bees can be high in urban areas due to the availability of alternate nest sites like wood fences or gaps in masonry walls.
Nesting material can be provided with a bee block, which is simply a piece of wood with correctly-sized holes drilled in it. Don't use pressure treated lumber, which may be toxic to bees. Holes should be between 3/16 inch and 5/16 inch in diameter (bees will use the hole that matches their body size), and four to six inches deep. The back of the block should be solid. Above-ground nests should face east to southeast and be protected from the afternoon sun. They should also be securely attached so they do not move in the wind.
To prevent disease, blocks should only be used for one year unless they are lined with paper straws that fit the diameter of the hole. Straws are removed yearly, thereby cleaning the cavity. Be sure to purchase straws specifically for bees, as regular paper straws do not work (an internet search for “Mason bee inserts” will turn up many sources). Straws can also be removed for inspection to see if they are being used.
Another option is bamboo, either plant stakes or purchased nest inserts. These are preferable to cutting your own, since purchased inserts are cut at the node to ensure they are closed at the back. At the Haven you'll see these in PVC tubes in one of our bee condos.
Finally, perennials with hollow stems can be pruned to leave six to eight inches of hollow old growth when spent flowers are removed. An example is sedum ‘Autumn Joy', which also provides a great late-season nectar source. Other garden options include leaving tree stumps and cut branches. Haven visitors will notice that we used the prunings from our orchard trees to line many of our secondary garden paths. I will post updates throughout the summer on the use of the garden's varied above-ground nests.
Most of the Haven receives full sun throughout the day, so garden visitors often ask, “What can I plant in the shade for bees?” Thanks to a generous donation from the California State chapter of the Daughters of the American Revolution we'll soon be able to answer. These funds will be used to install two new displays at the Haven: a dry shade garden under one of our valley oaks and a moist shade garden under our Mexican elderberry. Look for these when you visit this spring.
Here's what will be planted in the dry shade garden, listed in order of bloom time. Because the dry shade garden will be planted under a valley oak, I'll be using California native plants that need minimal summer water.
- Baby blue eyes (Nemophila menziesii): early spring-blooming annual that grows to 6 inches tall. Plant from seed the previous fall; will germinate and grow on normal winter rainfall. Stops blooming after a few days of hot weather.
- Chinese houses (Collinsia heterophylla): early spring-blooming annual that reaches up to 15 inches in height. Plant from seed the previous fall; will germinate and grow on normal winter rainfall.
You'll also see both of these in the Grower's Grove area of the garden as part of a wildflower mix used for mason bee (Osmia spp.) forage in almonds.
- Evergreen current (Ribes viburnifolium): Forms a dense groundcover up to 3 feet tall; cannot tolerate full sun. Dainty burgundy flowers in mid-winter. Red stems and fragrant foliage add to this plant's interest. Good low-water substitute for ivy.
- Golden current (Ribes aureum var. gracillimum): Sprawling shrub that can reach 10 feet tall and wide, but my experience is that is stays under 6 feet in the Central Valley. Small yellow flowers in mid-winter will develop into yellow-orange fruit. Good low-water substitute for forsythia.
- Ceanothus ‘Centennial' (Ceanothus foliosus x C. thyrsiflorus var. griseus): Every California bee garden needs ceanothus! Other shade-tolerant ceanothus in the Haven (in order of bloom) are ‘Valley Violet'; ‘Ray Hartman'; and ‘Skylark'.
- Creeping barberry (Berberis aquifolium var. repens): Forms a dense groundcover up to 2 feet tall and will grow in heavy shade. Leaves are pink to burgundy in winter but green up during the growing season. Yellow spring flowers are followed by blue berries.
- Coral bells (Heuchera spp.): I've planted both the cultivar ‘Rosada' (pink flowers) and the species Heuchera maxima (white flower). Both have stalks of small flowers reaching up to 12 inches borne in early spring. Plant these in masses for full effect. Foliage will burn in full sun.
- Valley oak (Quercus lobata): Grows quickly as a young tree to a height of nearly 100 feet when mature. Prefers alluvial soil (what we have at the Haven) where its deep roots can reach groundwater; excessive summer irrigation can cause root disease. Oaks are important habitat plants in California. Like most wind-pollinated plants, it is valuable to bees because it produces large amount of pollen.
- Coyote mint (Monardella villosa): About 12 inches tall, coyote mint does well at the front of a border where its purple flowers appear from spring to fall. Cut back in winter to keep it from becoming leggy.
- Snowberry (Symphoricarpos albus laevigatus): This woodland shrub grows about 4 feet tall and wide; its pink summer flowers are followed by white berries. Will grow in dense shade.
- California goldenrod (Solidago californica): Another bee garden workhorse that bears yellow flowers on 2 to 4 foot stalks from summer through frost; flowers best in full sun but will work in shade gardens. May spread too aggressively with regular irrigation.
- California fuchsia (Epilobium spp.): The Haven features the cultivar ‘Catalina', which grows about 3 feet tall. These valuable bee and hummingbird plants provide flowers from mid-summer through frost.
- California fescue (Festuca californica): This cool-season grass is at its peak in late spring, drying to tan by the end of the summer. Flowers rise another 1 to 2 feet above the 2-foot foliage.
- Deer grass (Muhlenbergia rigens): More typically used in full-sun settings, deer grass will grow in shade but remains smaller and doesn't assume the dramatic “pin cushion” shape.
Both grasses provide overwintering habitat for beneficial insects; bumble bees may nest under them. I've seen honey bees gathering pollen along the full length of deer grass flowers!
Chaparral currant 'Howard McMinn manzanita Wallflower
On President's Day we celebrate the achievements of our presidents, most notably George Washington and Abraham Lincoln. While their political and social accomplishments are well-known, many of our presidents have had connections to bees as well.
The Monticello web site tells us that Thomas Jefferson kept bees and owned the book Collateral bee-boxes: or, a new easy, and advantageous method of managing bees ; in which part of the honey is taken away, in an easy and pleasant maner, without destroying, or much disturbing the bees; early swarms, if desired, are encouraged, and late ones prevented (author Stephen White, 1759).
According to Abraham Lincoln in the Kitchen: A Culinary View of Lincoln's Life and Times by Rae Katherine Eighmey, our 16th president enjoyed cooking and his favorite food was apples. And we all know the folklore about George Washington and the cherry tree. Both these fruits rely on bees for pollination.
More recent are the current White House beehives.
While Washington, D.C. is currently snowed under, here in central California our weather is conducive to year-round honey bee activity. On any sunny day with temperatures over 55 degrees Haven visitors will see bees in the garden. Here are the red, white, and blue colors you'll see them foraging on this time of year:
Red (actually deep pink; bees do not see red):
Chaparral currant (Ribes malvaceum)
King Edward VII flowering currant (Ribes sanguineum ‘King Edward VII')
Compact Oregon grape (Berberis aquifolium ‘Compacta'); winter foliage is red but currently blooming with yellow flowers
Manzanita ‘White Lanterns' (Arctostaphylos spp. ‘White Lanterns')
Manzanita ‘Howard McMinn' (Arctostaphylos spp. ‘Howard McMinn')
Manzanita ‘Sentinel' (Arctostaphylos spp. ‘Sentinel')
Manzanita ‘Sunset' (Arctostaphylos spp. ‘Sunset')
Buckbrush (Ceanothus cuneatus)
Blue (actually shades of purple):
Bush germander (Teucrium fruticans)
Rosemary ‘Mozart' (Rosmarinus officinalis ‘Mozart'); this rosemary cultivar has outstanding deep purple flowers
Wallflower (Erysimum spp.)
Ceanothus ‘Valley Violet' (Ceanothus maritimus ‘Valley Violet')
Ceanothus ‘Ray Hartman' (Ceanothus arboreus x Ceanothus thyrsiflorus var. griseus)
Ceanothus ‘Julia Phelps'