July 2025 Plant Availability | | |
It’s summer! Around the nursery, the Northern Mockingbirds are teaching their young their musical repertoire (car alarm, train horn, phone ringtone, dove call), late season annual wildflowers are putting on a show (Clarkias! Gilia!), and in a quiet moment, we’re enjoying watching various caterpillars munching away on their host plants. Check out the Pipevine Swallowtail and Monarch butterfly cats digging in –>
What is a caterpillar?
The larval stage of a butterfly or moth. Most species go through multiple molts in this stage, and between each molt, are called an instar (first, second, third instar, etc. depending on how many molts they go through). Caterpillars are serious eating machines, mostly subsisting on plant material. For example, monarch caterpillars grow to almost 2,000 times their original mass!
Why are caterpillars important?
As we touched on with Keystone species in last month’s newsletter, in each phase of their life cycles, insects are an integral part of the food web! Caterpillars are food for a variety of other animals, such as birds, bats, lizards, mice, spiders, and more! Predation and parasitism of butterflies are high at all stages of development, so only a small portion of the eggs laid will survive to adulthood.
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How can we support caterpillars?
Maybe you’re seeing caterpillars in your garden, or out in nature, and are tempted to bring them home to care for them. Rearing caterpillars is often one of the earliest hands-on insect education moments we have as kids, and for conservation-minded folks, it can seem like a logical next step to help protect pollinators. Unfortunately, rearing and handling caterpillars often does more harm than good, and for monarch butterflies, it is illegal in CA, Canada, and Mexico.
So, as you’re shopping around the nursery, you’ll see our signs discouraging folks from purchasing plants that are already in use by caterpillars, and our staff will carefully check plants before purchase. If you had your heart set on raising caterpillars, don’t be discouraged, there’s still plenty more you can do to support butterflies in your own garden and community spaces:
- Plant larval host plants! Not only do these species provide food for caterpillars, their blooms support numerous additional insects as well. We’ve listed a few examples below
- Plant nectar plants for year round food for adult butterflies.
- Contribute to community science programs like the Monarch Larva Monitoring Project, iNaturalist, Journey North, Western Monarch Milkweed Mapping, and others
- Donate or volunteer with pollinator conservation organizations
- Encourage your community to do the same–habitat connectivity can start with door to door action!
Without further ado, read on for our edition of a caterpillar’s tasting menu of native plants–and plant these to keep them fed them in your garden, too!
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Narrowleaf Milkweed
Asclepias fascicularis
Available in D-16 pots for $7.70 each!
- This hardy perennial herb grows to 3′ tall and 1′ wide.
- Great for a bird garden and a butterfly garden.
- Can tolerate clay soils sopping wet in winter and rock hard during the summer drought.
- Antique pink flower clusters abound in the summer.
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Showy Milkweed
Asclepias speciosa
Available in D-16 and 1-gallon pots for $7.30-15.25 each!
- Showy Milkweed is a perennial, with 3′ tall stems and large gray five” leaves.
- Flowers splay like a Fourth of July firework.
- Plant in mixed borders, grassland gardens, or habitat gardens to attract monarch butterflies, birds, and insects.
- Spreads easily by underground stems. Use with large grasses such as wild rye, deer grass, and needlegrasses.
- Native across North America, found in northern coast ranges and Sierras of CA.
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Woollypod Milkweed
Asclepias eriocarpa
Available in D-16 pots for $7.70 each!
- Woollypod milkweed is a winter dormant perennial that can grow up to 3′ tall.
- This is one of 15 milkweed species native to California. Its cluster of cream with purple tinged flowers appear from May – October.
- It is very drought tolerant so plant it in full sun and will do best with very little summer water.
- Native to inland NorCal and coastal SoCal, Sierra foothills, and adjacent NV and Baja. Found in dry open grasslands, woodland openings, and chaparral.
“J20160707-0135—Asclepias eriocarpa/w Apis mellifera—RPBG” by John Rusk is licensed under CC BY 2.0.
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Yampah
Perideridia kelloggii
Available in D-16 pots for $8.95 each!
- This deciduous herbaceous perennial grows 1-2’ tall when in flower.
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Yampah is a very important larval host plant for the Anise Swallowtail butterfly. Mass together for borders, combine with yarrow, blue-eyed grass, soap plant, and asters for a meadow look.
- The pom-pom like umbels of white flowers appear in Spring through Summer. Will go completely dormant in the winter.
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Cow Parsnip
Heracleum maximum
Available in D-40 containers for $10.20 apiece!
- A tall (4-10’ tall) deciduous perennial.
- Cow parsnip has large leaves and can make a good accent plant for moist or part shaded areas. Although plants may last only a few years, they will reseed! Foliage can cause skin irritation–handle with care, and wear gloves.
- Butterflies (including old World Swallowtail, Black Swallowtail, Anise Swallowtail) and ladybugs love the flowers. Large white flowers with a sweet fragrance in the Spring.
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Red Fescue
Festuca rubra
Available in stub pots for $2.45 each!
- This rhizomatous to clumping perennial grass grows fast to 1 foot tall with flower spikes up to 2 feet tall. Space 12 to 14″ apart.
- Red fescue makes a lovely naturalistic “lumpy lawn” or soft groundcover that can be mowed to 2 inches. Does not need to be cut back but can be in summer if desired.
- It will do best in some shade in the hotter areas of the Bay Area. It is also great for a meadow garden, or does well in dry shade under oaks. Larval host plant to three Skipper species – Sachem, Umber, and Mardon.
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Checker Mallow and ‘Hem’s Hybrid’
Sidalcea malviflora
Available in 4″ pots for $8.30 each!
- An herbaceous perennial that grows 2 – 4 feet tall.
- Without summer water they will go dormant and reappear with fall rains.
- Does well in grassy areas or in borders. Combine with blue-eyed-grass, seaside daisy and native bunchgrasses.
- Large delicate showy pink flowers in the early summer.
- Host to Common Checkered Skipper, West Coast Lady, and Two-Banded Checkered Skipper
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Desert Globemallow
Sphaeralcea ambigua
Available in D-16 and 1-gallon pots for $8.95-16.50 apiece!
- A woolly perennial that grows to 3 feet tall and almost as wide.
- Flowers vary in color from orange to a rose-like salmon-color. The large flowers appear in loose clusters from spring to late fall.
- Low maintenance, can be cut back periodically to maintain shape. Works well in beds and borders as well as in a container.
- Globe mallow is the larval host plant for many butterflies such as the west coast lady, the painted lady, the common checkered skipper, the small checkered skipper, and the great white skipper.
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Venus Thistle
Cirsium occidentale
Available in D-40 pots for $10.20 apiece!
- Venus thistle is a rather large, annual-biennial thistle that can grow to 6′ tall. Unlike many introduced exotic thistles, this native species is not a troublesome weed.
- This native thistle is covered with short, soft, matted, white hairs and has very showy 1-2″ bright red flowers in the summer from May – July. Plant in full sun.
- Hummingbirds and adult swallowtail butterflies are attracted to the flowers, and Venus Thistle is a larval host plant for several moths, Painted Lady and Crescent butterflies.
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Blues & Hairstreaks:
Gray Hairstreak (left), Acmon Blue, Bramble Hairstreak
Larval Host Plants: various Legumes, Buckwheats
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California Buckwheat
Eriogonum fasciculatum
Available in D-16 and D-40 pots for $8.95-11.45 apiece!
- This fast-growing, long-lived evergreen shrub is found throughout the foothills of California, usually on fairly dry slopes. If forms a nice mound 2-3′ tall and wide. Space 3’ apart.
- The cream-colored flowers bloom April – September then turn rusty pink as they dry. A favorite of butterflies and honeybees!
- This is an excellent plant for erosion control and is tolerant of the worst soils. Once established make sure to minimize additional water.
- Larval host to Mormon Metalmark, various Hairstreaks, and Blues.
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Pacific Pea
Lathyrus vestitus
Available in D-40 pots for $10.20 each!
- Pacific Pea is a perennial species of wild pea with evergreen vines of twining tendrils that can reach up to 4-8 ft. long.
- Its appearance can vary quite a lot across subspecies, but generally Pacific Peas display showy pink to violet to white flower clusters that bloom prolifically throughout the first half of the year.
- This species usually occurs in part shade near oaks and makes the perfect trellis vine for a dry/partial shade garden, or can be let loose to climb through shrubs such as toyon, mountain mahogany, and chamise.
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Pipevine Swallowtail – Battus philenor
Larval Host: Dutchman’s Pipevine
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Dutchman’s Pipe
Aristolochia californica
Available in D-16 pots for $7.70 apiece!
- This robust, durable, rhizomatous vine will serve to knit your garden’s shrubs and trees together into loose thickets or attractively cover a trellis or fence with rope-like stems to 12 ft. in length.
- But it’s most noteworthy feature is its odd, bulbous, 1-1/2 inch flowers that appear in winter and spring, dangling from naked stems, and resembling a fanciful Dutchman’s pipe.
- Nice as a small-scale groundcover under oaks or with coffeeberry, spicebush, and pink-flowering currant. In California habitat gardens, this vine provides color, a larval food source of the pipevine swallowtail butterfly, and a nectar source for carrion-feeding insects including fungus gnats.
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Happy Summer from all of us at
The Watershed Nursery Cooperative!
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(510) 234-2222 | sales@thewatershednursery.com
Open Tuesday – Sunday 10am – 4pm
Closed Mondays & Holidays
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