While entomologists might hope that we select plants for our gardens based only on their value as bee resources, gardeners want attractive plantings. To bridge that gap, here are some suggested plant pairings for the bee garden that not only look good together but also provide complementary bee resources (i.e. one provides pollen and the other nectar) and have similar light and water needs.
Winter and early spring is when our native wildflowers shine. These re-seed easily, so a confined area like a parkway strip is a good place for them; sow seeds in late fall and let winter rains do the rest. If spread to other areas of the garden is a concern, pull these plants while they're still flowering before seeds are set. A great pair for full sun are California poppy (Eschscholzia californica) and phacelia (several species); orange and purple are complimentary colors and always look good together. A pair that can take some shade is Chinese houses (Collinsia heterophylla) and five spot (Nemophila maculata). Their purple and white flowers are an attractive combination; Chinese houses provides nectar and the five spot is a pollen source.
Honeywort (Cerinthe major 'Purpurascens') is an annual that provides both pollen and nectar. Be warned....it re-seeds with vigor! The Haven's plant is well-used by honey bees, and this year it was favored by a California bumble bee (Bombus californicus) queen. It's paired here with foothill penstemon (Penstemon heterophyllus), which covers the honeywort's sparse lower growth and provides nectar. Another spring combination are the California natives seaside daisy (Erigeron 'Bountiful') and California sunflower (Encelia californica). Yellow and purple are a pleasing combination and are colors that are attractive to bees. Both plants provide pollen and nectar.
Yellows and purple continue into the summer. Yarrow 'Moonshine' is a classic Mediterranean garden plant that provides pollen; it's paired here with 'Purple Ginny' sage, but it works well with any of the autumn or little-leaved sages (which are nectar sources). Another summer combination is catmint (Nepeta x faassenii), which provides nectar, and the seaside daisy (Erigeron 'Bountiful'), which provides both pollen and nectar. Both will re-bloom with regular deadheading.
For fall bloom, another yellow and purple combination is bluebeard (Caryopteris x clandonensis) and goldenrod (several species/cultivars). Both are pollen and nectar sources that grow in part shade; goldenrod will spread over time so keep that in mind when selecting a planting location.
A frequent question from Haven visitors at this time of year is what we do to prepare the garden for winter. Most of our winter pruning is done in January and February, so we do little at this time of year. Leaving spent flowers and dried stems ensures plenty of seeds for the birds and overwintering habitat for beneficial insects. Garden volunteers often see scores of ladybird beetles emerge from the base of plants when they are pruning in the January.
The other winter task at this time of year is consolidating the bee hive. We reduce the hive from three boxes to two, and place frames with the most brood (immature bees) at the center of the lower box so they are protected from the colder outer areas.
The hive will be left unopened for the winter, although I'll continue to monitor activity at the entrance over the next few months.
From a human perspective, we don't often think of February as an important time for flowering plants, but for bees it's another matter. Honey bees are out foraging when it's sunny and over 55 degrees, while native bumble bees that become active early in the year are in need of pollen and nectar resources to grow their colonies. The solitary bee Osmia lignaria -- an important alternate pollinator in early fruit and nut crops -- is also active.
A group of native plants that provide resources for all these bees with their February flowers are the currants. The first to bloom is chaparral currant, Ribes malvaceum; we grow the cultivar 'Dancing Tassels' at the Haven. This plant starts to flower in January and will continue its showy display through February. In addition to bees, look for lots of hummingbirds on this plant.
Following close behind is fuchsia-flowered gooseberry, Ribes speciosum. Primarily a hummingbird plant, the photo shows how accessible the pollen is for small bees. We don't grow this at the Haven, as it has large thorns that could be a visitor hazard. It can be espaliered up a fence, where the thorns can serve as a living security system. Another consideration when siting this plant is that it copes with our summer heat by losing its leaves in July.
Next to bloom, and the most commonly planted, is the evergreen currant, Ribes viburnifolium. This plant's stems tend to arch over and root where they contact the ground, creating a dense groundcover. I've often seen this plant placed in full sun, which it can't tolerate, leading to leaf scorch and poor growth. A better location is under native oaks or any other dry, shaded spot. Although the flowers are not showy, they are still valuable for bees.
The last plant in this group to bloom is golden currant, Ribes aureum, which will start to flower around the middle of the month. Its bright yellow flowers make it a good, low-water substitute for non-native forsythia. It can tolerate a range of watering regimes; at the Haven we grow it in both a wet area next to a bee waterer and in a dry area under a valley oak. It tends to stay smaller and lose its leaves earlier (around late August) in the dry area but still flowers well.
How is the California drought affecting bees? Many Haven visitors have asked that question. Drought affects bees in several ways; the good news is that we can provide some relief in our bee gardens. Some considerations:
Honey bees need water to cool the hive and to dilute the honey they feed to developing bees. This is why it's essential to include a water source in your bee garden. See this previous Bee Gardener post for more information.
The honey bee-parasitic varroa mite, Varroa destructor, has had a devastating effect on honey bee health. The good news is that multi-year droughts can reduce the mite's reproductive rate (Environ. Entomol. (2003) 32(6): 1305-1312).
Drought-stressed plants produce fewer, shorter-lasting flowers. Lack of adequate, high-quality forage has been identified in a USDA study as a major factor in bee health decline.
Less obvious than the absence of flowers is the quality of the food they provide. In a study of squash plants subjected to simulated drought, it was determined that the daily pattern of nectar secretion was unaffected by drought. The volume and concentration of nectar declined with the length of the simulated drought, however, indicating a negative effect of drought on the floral resource that bees depend on (Apidologie (2012) 43:1–16).
Many of our native bees are feeding specialists that will only use one species or genus of plant. What happens if that plant suffers during drought? Many animals native to areas with regular dry periods have evolved diapause as a survival mechanism. A study of in bees in the southwestern US desert found that they were able to reliably use environmental cues to enter diapause when their plant resources were affected by drought (Proc. R. Soc. B (2013) 280: 20122703).
Effective use of limited water in the bee garden
Many communities are under mandatory water restrictions, and groundwater levels are at record lows throughout California. How do we balance this with the needs of these vital insect pollinators?
- Save the rest of this year's water for the plants that have yet to bloom. Fall and winter are critical times for honey bee foraging to ensure ample honey stores for the winter. In the Haven we are reducing irrigation to the plants that are finished blooming for the year so we can focus water use on the sunflowers, asters, sedums, and other plants that will bloom until frost.
- Provide an efficient water source. The Haven's self-watering container made from a soaker hose runs on a timer. This provides water for our bees while re-using the water for irrigating the plant in the container.
- Plant drought-tolerant bee plants for next year. We have suggestions on the garden's web site.
Some of the best all-around plants for bees and beneficial insects in the California garden are the buckwheats, Eriogonum spp. Native to California, a selection of just a few species will provide bloom for most of the spring and summer in even the hottest and driest of gardens. These durable plants grow in full sun to part shade and require well-drained soils; plant them on berms to achieve better drainage in heavy soils.
This large genus includes over 125 species, one of the largest genera of California natives. About a dozen of these are sold for landscape use, including both coastal and interior species. The Haven's buckwheat plants host smaller bees along with a diversity of insect natural enemies and butterflies.
Buckwheats in the Haven
California buckwheat, Eriogonum fasciculatum. This plant's slender leaves look similar to rosemary. Roughly four feet tall and wide, this plant has varying growth habits from upright to arching. The latter will root where stems touch the ground. It is covered in small white flowers tinged with pink from June to fall; they turn a rusty red at the end of the season for additional color. Prune back about halfway each fall to keep a dense shape. Native to chaparral regions in the southern half of the state.
Saint Catherine's lace, Eriogonum giganteum. This UC Davis Arboretum All-Star shrub reaches six to eight feet tall and wide; add another foot in each direction for the showy flower stalks. This plant works as a specimen or grouped as a hedge. As with California buckwheat, it flowers from June to fall and then the flowers turn a rusty red. Prune each fall to keep a compact shape and prevent the plant from becoming woody; it will not re-sprout from woody stems. Native to chaparral regions in the southern half of the state.
‘Ella Nelson's Yellow' naked buckwheat, Eriogonum nudum ‘Ella Nelson's Yellow'. Haven visitors have seen this plant's bright yellow flowers for the past three months. The common name comes from its growth habit: the plant dies back to the ground in winter and flower stalks often emerge before the foliage. Cut back spent flowers to encourage additional blooms and prevent numerous seedlings if these are not desired. Native from the coast to the Sierra.
Red buckwheat, Eriogonum grande var. rubescens. Delightful raspberry colored flowers cover this plant in June. It grows to a three-foot wide mound and tends to be relative short-lived in gardens. Native to the Channel Islands, in the Davis area it does best with afternoon shade and water every two to three weeks.