June 2023 Plant Availability |
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Greetings,
Happy June! This month the 19th – 25th is National Pollinator Week, which is an annual celebration in support of pollinator health. It’s the perfect time to raise awareness about pollinators in decline and what we can do to protect them. Butterflies and honeybees often get the spotlight in the movement to save the pollinators as the charismatic megafauna of the insect world, but we think our lesser known California native bees are just as fascinating and important! Keep reading if you want to learn about the incredible diversity of California native bees, the threats they are facing, what we can do to support them, and the best native plants we have available right now to support native bees in your own neck of the woods 🙂
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Why are pollinators so important?
Pollinators are ecological keystones that help hold ecosystems together by supporting plant reproduction and diversity. More than 85% of flowering plants require an animal (usually an insect/invertebrate) for pollination (i.e. reproduction)! Without pollinators, the fruit and seeds that many birds and mammals (including humans) rely on would be scarce. There is growing evidence of declining biodiversity and abundance of both wild and managed pollinators, which will likely have devastating impacts on human food security if this trend continues.
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Butterflies and hummingbirds get all the attention, so let’s talk bees!!! |
Most of the evidence regarding the pollinator crisis is focused on honey bees because they are so intensively managed and publicized, but many folks are unaware that honey bees are not actually native to North America– they were brought over from Europe! Plus, although European honey bees are used widely for crop pollination throughout the U.S., our native bees are actually more efficient pollinators of many of our crops!
There are ~3,600 species of bees native to North America, and ~1,600 native to California. Most of our native bees are solitary, gentle, and unlikely to sting. Roughly 70% of bee species nest in the ground, most often in bare/exposed soil (they prefer sandy to loamy soils, but some nest in clay too) where they spend most of their lives underground. Around 30% of bees nest in cavities of stems or dead wood, laying their eggs in beetle holes or creating nesting chambers in hollow/pithy stems. The cavity nesting bees also use a variety of materials to divide their brood cells, such as chewed up plant material, mud, and leaves! Less than 1% of bees are hive/colony nesting like honey bees and most of the 47 species of bumble bees native to North America.
[Some of our favorite types of native bees include Cuckoo Bees (they are social parasites that utilize the same strategy as cuckoo birds, laying their eggs in the nests of other bee species) Green Sweat Bees (they have a spectacular metallic green sheen, and get the common name “Sweat Bees” because they are known to lap up the perspiration from our skin), Leaf Cutter Bees (they cut off chunks of leaves and petals, carry them back to their nests, and line their brood cells with them. Redbuds are among their favorite plants for this), and Bumblebees of course!]
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Key drivers of pollinator decline 🙁 |
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Habitat loss due to urbanization/development, pesticide contamination, and the loss of key plant species that pollinators depend on
- Pesticides
- Insecticides are highly toxic to pollinators (bees are especially sensitive because they have a limited ability to filter out toxic substances. Additionally, most of our native bees are solitary, so they do not have colonies to buffer the impacts of pesticides like European honey bees do).
- Herbicides primarily have indirect effects on pollinators due to the removal of plants, but new research shows direct toxicity to pollinators– impacting their development, navigation, and immune systems.
- Fungicides can have some insecticidal properties and contributes to a loss in wild bee abundance and the reduction of their ability to fight off diseases.
- In urban landscapes, pesticides are primarily used for cosmetic reasons and shockingly have more pesticides per acre than most agricultural fields! They also affect water quality from runoff into streams and rivers.
- Nonnative Species and Disease
- Honeybees and other nonnative bees that get moved around the country and/or shipped lead to higher spread of disease (both from colony to colony and to individual bees when interacting at the same flower)
- They also compete with native bees for floral resources
- Climate Change Effects
- Physiology- Changes in temperature can affect pollinator survival, growth, and reproduction rates, as well as the amount of time they are able to spend foraging for food
- Phenology- Changes in the timing of biological events can lead to mismatches in pollinator and plant responses to climate change
- Range Shifts- Species distributions are changing in response to the changing climate, and these range shifts require habitat for the pollinators to move to as well as corridors of habitat for them to move through
- Species interactions- disruption of the balance of predator/prey interactions and disease prevalence
- Changes in plant quantity, quality (ex: fewer flowers and less nectar are produced during droughts), and diversity
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So what can we do to support pollinators? |
Create high-quality pollinator habitat and work together to increase habitat connectivity!
High-quality pollinator habitat includes food resources (pollen, nectar, and larval host plants), shelter and nesting sites (a variety of some undisturbed areas, small patches of bare soil without landscape fabric or heavy mulching, areas with direct sunlight, some logs/snags/brush piles if possible, and pithy stemmed plant species), and protection from pesticides and pathogens. The greater abundance and diversity of plants, the better! It’s also important to have plants that flower at different times of year (ideally at least 3 species flowering at all times) so that our pollinators have food resources throughout the entire season that they are active (in California this can be all year-long). Native plants are by far the best for this, because they support a wider range of pollinators across the board, and are more likely to support specialists that have closely evolved with particular plant species. Keep in mind that no space is too small for this, and you can make a difference even if you’re limited to a small container garden! The more connected little pockets of habitat are, the greater the positive impact for pollinators will be! Creating “stepping stones” and pollinator pathways along roadways and agricultural fields have shown tremendous promise for supporting pollinators and increasing gene flow between them. In general, more habitat will support larger populations, which are less vulnerable to extinction and can better withstand bad years of extreme events associated with climate change.
Reduce the risk of pesticides!
Managing pests and diseases using preventative strategies and Integrated Pest Management (IPM) principles, supporting beneficial insects/”natural enemies,” and responding to underlying issues rather than defaulting to pesticides as a quick fix can go a long way for reducing pesticide use in urban environments.
***FYI there’s a free CNPS Naturehood Gardening webinar tonight (June 1st) from 5:30-6:30pm on this very topic titled “Get Rid of Garden Pests the Natural Way”***
Advocate for change!
Advocating for pesticide reduction and the creation of pollinator habitats in your local communities and at the state and federal level is invaluable for making lasting changes to protect the pollinators that we depend on! Here are some of the recent accomplishments of the Xerces Society for some inspiration and hope: https://xerces.org/advocacy
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Phew! If you made it through all that, thanks for reading and we hope you learned something to spark your curiosity and inspire you to help support and protect our native bees and other pollinators <3
Below are our featured plants of the month that are among the best species for California native bees 🙂
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Buckwheats
California native buckwheat species are the real M.V.P.’s in native gardens– they attract pollinators by the dozens (especially native bees) with their dense clusters of flowers that act as landing pads for easy access to the bounty of pollen and nectar that they provide. They are also host plants for caterpillars of a variety of butterfly species, as well as a source of food for birds via their seeds.
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- Small perennial shrub
- Grows 6″ – 1′ tall
- Blooms of white to pale pink or yellow cotton ball-like flowers appear in late spring/early summer
- Drought and heat tolerant
- Prefers full or nearly full sun and needs excellent drainage
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- Small evergreen sub-shrub
- Grows quickly to form nice mound about 2′ tall and wide (space 2-3′ apart)
- Blooms from April to September with round clusters of cream-colored flowers that turn rusty pink as they dry.
- Attractive additions to rock gardens and mixed borders as a companion to seaside daisies, sandhill sagebrush, quail bush, etc.
- Tolerant of poor soils and great for erosion control
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- This shrub is the largest of the buckwheats, growing 4′ tall x 5′ wide
- Attractive wooly silver-green oval leaves are the perfect complement to its profuse clusters of small white flowers
- blooms April to fall
- No summer water needed once established
- tolerant of clay, but will thrive best in well-drained soil
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- Fast growing, long-lived evergreen shrub
- Forms nice mound 2-3′ tall and wide (Space 3′ apart)
- Blooms April to September with cream colored flowers that turn rusty pink as they dry like the Coast Buckwheat
- Excellent for erosion control and tolerant of poor soils
- Minimize additional water once established!
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Pithy-stemmed plants for cavity nesting bees |
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- Deciduous shrub
- Grows up to 8′ tall
- long-lasting large pink flowers with rich rose fragrance bloom from spring to summer
- Adapts to heavy clay soil; spreads via suckering roots to form thicket
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- Deciduous shrub to small tree
- Grows 15′ tall
- attractive light green foliage appears very early in spring, and large clusters of fragrant creamy white flowers are abundant from spring to early summer
- Edible fruit (only eat after cooking!!) is both medicinal and delicious!
- Prune to help keep its shape
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Spring-blooming Superstars |
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- A favorite among bees for its abundant nectar
- 2-4′ perennial with 3′ spikes of reddish flowers
- Blooms March through July
- Great for shady gardens
- Drought tolerant, but looks better for longer with a bit of summer moisture
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- A favorite among leaf cutter bees for their large, rounded, flexible leaves
- Deciduous shrub to small multi-trunked tree
- Grows 14′ tall
- Showy magenta flowers bloom February to April
- Pairs well with ceanothus, douglas iris, and coral bells
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- Herbaceous perennial
- Grows 1-2′ tall (space 1′ apart)
- Purple fiddleneck flowers bloom from March to September
- Important nectar source for endangered Mission Blue Butterfly and lots of native bee pollinators including bumblebees
- Tiny hairs on leaves can cause skin dermatitis, so use gloved when gardening with this species!
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Available in D16 pots for $6.60 each!
- Semi-evergreen herbaceous perennial
- Grows 1-3′ tall
- White umbel flower clusters bloom March through June (cut back after blooming)
- Spreads via rhizomes, which makes it a great slop stabilizer
- Grows in a variety of environments throughout California, making it a reliable food source for a number of native bee, hover fly, and butterfly species
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- Evergreen shrub
- Grows 5′ tall x 3′ wide
- One of the showiest CA native species, producing tons of fragrant white blooms from April to July
- adaptable to variety of soils, but does best with well-drained soil
- minimal water needs after established
- cut back periodically to help it stay fresh
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Available in 4″ pots for $7.15 each!
- Perennial herb
- grows 2-3′ tall x 4-5′ wide
- densely clustered purple/blue flowers bloom April to September
- pioneer species used by many native insects for its nectar and pollen
- Great for erosion control as it can grow aggressively
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Sources:
“Beyond the honey bee: Learn more about California native bees” from the UC Davis Arboretum
“Science: Pollinators” from the California Department of Fish and Wildlife
“5 Ways to Increase Nesting Habitat for Native Bees” by Justin Wheeler from the Xerces Society
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Stay Safe, ‘Bee’ Well, and Go Natives!
Happy Planting! From all of us at The Watershed Nursery.
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- Landscape and gardening professionals receive a 10% discount on all plants (except for sale plants) purchased for professional use.
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Resellers: All the plants are available for wholesale purchase. Provide us your resellers license to receive a 20% discount on the listed price (except for sale plants) and no sales tax.
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The Watershed Nursery | 510.234.2222 | sales@thewatershednursery.com |
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