By Pat Hitchcock, UC Master Gardener of Napa County
Napa County Master Gardeners recently had the opportunity to hear a wildlife specialist talk about managing vertebrate pests in gardens and landscapes. Participants were asked to list their five most troublesome vertebrate pests. Mine would be gophers, ground squirrels, birds, deer and voles.
To my surprise, the group's top five did not include ground squirrels but did include tree squirrels. Obviously, what is going on in my garden is not symptomatic of Napa Valley in general.
What is the problem with tree squirrels? Tree squirrels not only feed on nuts and fruits but also sometimes forage on ground crops such as strawberries and tomatoes. In addition, their gnawing behavior can damage tree branches when they chew off the bark to get at the cambium layer. They can also gnaw their way into buildings and through phone lines.
Finally, particularly in the fall, they have a habit of digging holes in the ground to bury acorns, nuts and seeds. The digging disturbs lawns and garden beds, and the buried seeds often sprout in spring. I suspect that the lone walnut tree on my property was the result of squirrel activity many years ago.
Squirrels are hard to control in urban and suburban settings because of their mobility and also because some people feed and provide nest boxes for them. I guess people perceive them as cute. But if you are trying to harvest almonds or other nuts from your backyard trees, you are more likely cursing them.
Three common tree squirrels inhabit Napa Valley. One species is a native, the Western Gray, and is considered a game animal. That means you need a permit from the California Department of Fish and Wildlife to kill them. Ditto for the Eastern Gray Squirrel, which was introduced intentionally into Golden Gate Park in San Francisco and has since expanded its territory.
The third species of squirrel commonly found in Napa County is the Eastern Fox Squirrel. This one tends to be the biggest pest but is not considered a game animal so may be hunted without a permit.
You can't deal with a problem until you identify it, so I've been observing the squirrels that live in my neighborhood. Gray squirrels have a white underside; the Eastern Fox Squirrel has a brown belly. It appears that I have some of both types.
If your squirrels are invading buildings, you can exclude them by finding all of their entrances and blocking them. Sheet metal and ¼-inch hardware cloth are useful for this approach. Note that squirrel entrances are usually up high near phone lines and in attics.
It's hard to keep squirrels out of trees due to their superb climbing and jumping skills. Sometimes, if there is enough other food around, they can be kept out of a fruit or nut tree with netting. But they can easily gnaw through netting if they want the fruit.
Trapping can help control squirrels, but if you use a live trap, be aware that it is illegal to relocate wild animals under California law. You are allowed to euthanize the Eastern Fox squirrels in a humane way. Shooting and gassing with carbon dioxide are considered humane, but drowning is not.
Several kinds of kill traps may be used on fox squirrels. Set them on routes that the squirrels travel, then anchor and cover them to prevent predators from taking the squirrel and trap away. For more detail on trapping, consult University of California Pest Notes online at www.ipm.ucanr.edu.
Chemical repellents have not been shown to be effective, and squirrels quickly become accustomed to noisemakers. Some dogs who have full run of a yard will keep squirrels at bay. Natural predators in urban areas have negligible effect on squirrel populations. Depending on local laws about firearms use in your area, it may be permissible to shoot the Eastern Fox Squirrel. But to shoot a Western or Eastern Gray Squirrel you need a permit.
After considering the options, I've concluded that the squirrel activity in my own yard is tolerable. The squirrels get most of the walnuts on my tree before I do, and I have to dig up walnut seedlings from time to time. But considering the rural nature of my property and the many other woody plants that self-sow (cotoneaster, privet, live oaks), these are problems I can live with. I guess I'll continue to buy my walnuts at the farmers market.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
An Iris Primer, by Iris Craig
My mother loved flowers: she named me Iris. Having a flower name has affected my life and perhaps led me to be a Master Gardener.
When I purchased my house 40 years ago, friends arrived with iris rhizomes for my garden. Not sure how to plant them, I asked for advice from my friend, Alice, who inherited an iris garden from her mother. Some of those gifts—often neglected, rarely transplanted—still bloom today. Abandoned houses sometimes have iris blooming long after the owners have left.
Iris is the largest genus in the Iridacadae family. Iris have thrived in the wild for thousands of years and figure in cultures throughout the world. In Greek mythology, Iris is the rainbow goddess who brings messages from humanity to the gods. In Roman mythology, she walks the rainbow to the heavens carrying messages to the gods.
Egyptian and Indian cultures used iris rhizomes for healing and for making perfume. Orris root, made from the rhizomes of bearded iris, was burned to create scents pleasing to the gods. Dried iris rhizomes were an industry in Florence in the 19th Century, and the flower became the emblem of Florence.
Iris represents the renewal of life. Clovis I of France chose the fleur-de-lis for his emblem in the sixth century. The fleur-de-lis continues today as the emblem of New Orleans and the state flower of Tennessee.
There are about 280 species of iris. Moors brought iris to the Alhambra in Spain. When Columbus set sail for America, Holland had already developed many new species. Some American iris came across the Atlantic with early settlers and date back to the 1600s.
Twenty-eight native species are found today in North America. The three main natives are Blue Flag, Louisiana and Pacific Coast iris. This last is native to California and Washington State. All attract pollinators and are a colorful addition to your garden.
The Siberian bearded iris, with more than 200 species and a multitude of colors, is the one often found in Napa Valley gardens/ These non-natives can be divided into two main groups: bulbs and rhizomes.
Rhizomatous iris grow horizontally close to the surface with underground stems that supply food for the plants. The common bearded Siberian and Japanese iris grow from rhizomes that are planted in the summer. Bulbous iris, among the most reliable, are repeat bloomers in our area. These include Dutch iris and the dwarf reticulated iris, both of which are best planted in October with other bulbs.
When iris have been in the ground for a couple of years and have fewer blooms, it is time to divide and replant. Rhizomatous iris do well when divided every three to five years. Here's how:
With clean garden shears, cut back the leaves by one third. Next, lift out the entire clump with a shovel or pitchfork. Using a sharp knife dipped in 10 percent bleach solution after each cut, separate the rhizomes.
My friend Alice called the main, larger rhizome with last season's bloom stem at one end the ‘mother.' The smaller rhizomes attached to her are her children and, thus, the pieces to be broken off and transplanted. The ‘mother' rhizome is discarded. The new healthy (children) transplants are firm, with roots, and a fan of five or more leaves.
Check the new rhizomes for soft-rot, a bacterium (erwinia carotovora). Victimized iris have wilted leaves, and the rhizome emits a foul odor. It occurs when the plants are over-watered. If rot is evident, while digging up the plant, cut off the affected areas with a clean knife, expose the healthy rhizome to the sun, and wash with an anti-bacterial soap. Do not put the leaves and diseased rhizome in your compost.
Next, check for the iris borer (Macronoctua onusta). This moth lays eggs on the leaves of old iris leaves and debris. In midsummer, the caterpillars chew through the leaves, find their way down to the rhizome and begin eating it, causing soft rot and possibly death. The best way to prevent damage by this pest and others is to water lightly and keep the garden free of debris and weeds.
Water and excessive moisture are the source of soft-rot. Iris do well when planted in the heat, during the dry weather of summer. In Napa Valley, plant late July through September to minimize rot. Choose a sunny, well-drained area in the yard. A few varieties found on the edge of ponds can manage moisture; however, most iris cannot.
Plant groups of the same variety 18 to 20 inches apart. Dig a hole five inches deep. Place a mound of dirt in the center. Set the young, healthy rhizomes on the top of the mound with the roots hanging down the sides. Cover the roots but leave the top of the rhizome exposed to the sun. If planted too deep, iris may not bloom and could rot.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
By T. Eric Nightingale, UC Master Gardener of Napa County
I love California native plants. I also love to eat. Until recently I had not considered the possibility of an overlap between these two passions. Eventually it occurred to me that there must be many edible native plants to complement those brought here by European settlers.
Would it be possible to plant a garden of perennial natives that also supplies food? I found the idea appealing, in part because I figured such a garden would produce food easily. Our state's native plants tend to need less care, often less water and can be less prone to attack by insects and disease. I realized that that my fantasy of walking through my self-sustaining Californian Eden, picking fruit to eat as I wander, was probably not achievable, but still I set out to investigate the possibilities.
Indeed, many native plants are edible, but you must proceed with caution. Some are safe to consume just as they are, but many require some form of preparation to make them safe, or even desirable, to eat. Before eating anything unfamiliar or anything you have foraged in the wild, do your research and be sure you are not taking a risk.
That said, I have found many exciting edibles around our state, many that have been right under my nose for a long time. Most fascinating to me were the edible cacti and succulents. The fruit of the prickly pear cactus (Opuntia spp.) is well known. New to me, however, was the chaparral yucca (Hesperoyucca whipplei), the flowers and seeds of which can be eaten either cooked or raw.
The barrel cactus (Echinocactus acanthodes) grows a crown of attractive flowers that leave behind small, edible (but not very tasty) fruits that resemble miniature pineapples. More appealing is purslane (Portulaca oleracea). Often considered a weed, this tender succulent is flavorful and a great addition to salads.
Sedum spp., also called stonecrop, is used as a ground cover in drought-tolerant landscaping. All species are technically edible but can cause gastrointestinal distress if consumed in high quantities. They apparently have a peppery flavor that may justify their addition in a creative meal.
The leaves and flowers of the ice plant (Carpobrotus edulis) are reportedly edible raw. You will recognize the pointed leaves and brightly-colored flowers of this vine-like succulent at almost any stop along the California coast. As this plant is not native, and is in fact extremely invasive, you may be doing a public service by consuming it. Perhaps if we all made a habit of eating ice plant salad, we might help clear the way for native plants to reclaim their lands.
Many native shrubs produce edible berries. My favorites are currants and gooseberries (Ribes). The berries are tasty and can be made into jam, but these shrubs sit at the top of my list for their flowers. The colors and shapes are impressive, guaranteeing aesthetic as well as culinary appeal. The berries of the black hawthorn (Crataegus douglasii) shrub are delicious and useful in pies and preserves. The foliage and flowers, while not particularly striking, are attractive and a fine addition to any landscape.
Berries in the wild are often misidentified, so I recommend sticking with home cultivation. Birds like them, too. While growing currants and gooseberries is an excellent way to support local wildlife, it can be frustrating if you dream of a pantry full of gooseberry jam.
One group of often-overlooked edibles is what I dub “roadside salad.” Most of the members of this little club may be recognizable to many people as weeds. One such roadside trooper is miners lettuce (Claytonia perfoliata). Its disc-shaped leaves are tender and have a delicate flavor. To add some zing to your roadside salad, look for the peppery bittercress (Cardamine spp). This plant has a much more traditional weed-like appearance.
Surprising to me, native cattail (Typha domingensis) is also edible. The young shoots can be eaten raw and are said to taste like corn. The seeds and starchy roots can also be used if cooked.
One definition of a weed is a plant growing in the wrong place. If we appreciated these plants a bit more, we might start to view them not as weeds but as convenient snacks.
Workshop: U. C. Master Gardeners of Napa County will conduct a workshop on “Rose Care” on Saturday, June 2, from 10 a.m. to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Roses will grow without any care. But they will thrive with a little TLC. UC Master Gardener rose experts will answer your questions regarding rose care at this popular forum. By June, the first spring blooms have faded, and many plants are beginning to show evidence of stress. Look for black spot, rust, mildew and possible aphid infestation. Bring samples for identification. Online registration (credit card only); Mail-in/Walk-in registration (check only or drop off cash payment).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
Penny Pawl, U. C. Master Gardener of Napa County
Worms are not native to North America. About 20,000 years ago, our continent experienced an Ice Age, along with Europe and Asia. The phenomenon decimated the worm population, with the only survivors in parts of Turkey and the Mediterranean.
Over time, as Eurasians and Europeans began migrating to new lands, they brought plants for their new homes with them. Worms and other critters hitched a ride. On the East Coast of the U.S., these worms have changed the ecosystem because they eat the fallen leaves that trees also depend on for nutrition. This phenomenon is changing East Coast woodlands.
As the immigrant settlers moved across the country, so did their worms. In the Western U.S., worms have benefited the land and consequently the crops that people grow.
If you dig in damp soil, you will probably run across at least one worm. These earthworms (Lumbricus terrestris) live in the first 12 inches of soil. Their digestive systems turn soil into ever finer soil, and their castings improve the health of the soil. Worms also turn the soil, creating tunnels for water and roots. They won't thrive in compacted soil.
Night crawlers (Eisenia hortensis) also live in the soil. However, when the air is damp, they come to the surface and feed on plants there. They are much bigger than red wigglers. Once I put two night crawlers in a worm compost bin. When I cleaned the bin the following year, there were still just two night crawlers in the bottom of the bin. These worms had no interest in composting. However, some night crawlers from Europe and Africa will apparently do this work.
Red wigglers (Eisenia fetida, also known as fishing worms or manure worms), are the kings of composting. They are the worms you find under a stone, pot or pile of leaves. They only eat decaying matter.
Once I put a layer of maple leaves in one of my bins. I seem to have raked up some maple seeds, too, because a week later I had a crop of baby maples in my compost. The worms ate the leaves but not the seeds, which were still fresh enough to sprout.
Red wigglers eat or chew 90 percent of what you give them and that includes newsprint, plain cardboard, egg shells, daffodil leaves, spent flowers, vegetable leftovers, coffee grounds and animal fur. From these materials they produce compost, a mild fertilizer that you had a hand in.
Spread your worm compost over a garden bed, water it in, and the nutrients return to the soil. A lot of gardeners also put a little worm compost in the planting holes for their vegetables for an extra boost. I feed my potted plants with a handful of worm compost.
African red wigglers (Eudrilus eugeniae) grow much longer than our red wigglers and eat more. The two types can survive side by side because they are not necessarily interested in the same decaying material. The African worms need higher temperatures, but I have corresponded with someone in Michigan who is successful raising them in his garage.
Other critters will move into your bins, too. Sow bugs or pill bugs will be the first to arrive, and their manure is just as good as worm castings. My compost-bin residents have included small toads, earwigs, slugs, snails, an occasional small snake (they like worms), a few lizards, ants and various flies. Most of these creatures coexist but I do get rid of the fruit flies.
This year I am experimenting with putting compost bins in my raised beds, a technique common to African keyhole gardens. I put a compost bin in the middle of each bed so the worms can travel back and forth and hopefully fertilize the bed they are in. Only time will tell whether this experiment is successful, but I will report back.
Workshop: U. C. Master Gardeners of Napa County will host a workshop on “Rose Care” on Saturday, June 2, from 10 a.m. to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Roses will grow without any care. But they will thrive with a little TLC! Master Gardener rose experts will answer your questions regarding rose care at this popular forum. By June, the first spring blooms have faded, and many plants are beginning to show stress. Look for black spot, rust, mildew and aphids. Bring samples of what's plaguing your roses. Online registration (credit card only); Mail-in/Walk-in registration (check only or drop off cash payment)
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
By Cindy Watter, UC Master Gardener of Napa County
About 25 years ago, my next-door neighbor brought home a half-dead tangle of a plant that she called a passionflower (Passiflora). She planted it in a large trough and set to work spraying it lavishly with Miracle-Gro.
It must have been a case of the right plant in the right place because it soon tumbled over the fence and took over my yard. For the last quarter-century birds have scattered the passion fruit seeds, vines the size of boa constrictors have twined up my walnut tree, and the exuberantly beautiful blue passionflowers have provided a backdrop for family portraits.
Most importantly, the plant has provided habitat for the gulf fritillary (Agraulis vanillae), an orange butterfly that was introduced to the Bay Area from the South American tropics around 1908 and has now spread as far north as Sacramento.
There's something so cheering about looking out the window at a cloud of orange butterflies fluttering around the blue passionflowers. It is a delightful way to begin the day.
Butterflies are important pollinators, but most people love them because they are so pretty. The fritillary larvae eat the passionflower leaves, and it's fun to watch the caterpillars creeping on the foliage. (Children find this stage especially fascinating.) The Napa climate is generally hospitable to butterflies, and most plants they like do well here. It is not at all difficult to create a butterfly habitat in your yard.
Butterfly bush (Buddleia) blooms in a variety of colors, including purple, rose, yellow and cream. It likes well-drained soil and full sun, although some varieties thrive in partial shade. It is not unusual to see a buddleia covered with butterflies, enjoying its nectar and pollen while slowly waving their wings. Some Buddleias can easily reach 15 feet. They do spread; seeds travel through a neighborhood and sprout. If you are concerned about that, prune them to a height of 10 inches after they flower but before they set seed.
Many California native plants are irresistible to butterflies, and most natives need little water to thrive. The California wild lilac (Ceanothus) can be a shrub or ground cover, with blooms in an assortment of colors, although blue is the most common. They need almost no water in summer, although some fog-belt varieties appreciate a little moisture then.
The flannel bush (Fremontodendron), which sports butter-yellow flowers, is completely drought tolerant. The foliage can irritate skin (the leaves have a felt-like texture on the underside), so wear gloves when working with it and keep the plant away from paths. It is perfect against a stone wall or on a slope, and pollinators love it.
Another garden showstopper is the Matilija poppy (Romneya coulteri). This perennial can grow nine feet tall and makes me think of fried eggs, sunny side up. The flowers have white crepe paper-like petals, with a fluffy yellow center, and greyish green foliage. I had no luck growing them from seed, and no wonder: they propagate by way of rhizomes. Even then, Sunset's Western Garden Book recommends that you burn pine needles on top of a foil-lined flat of sprigs from the spreading roots before planting them.
It's much easier to buy a plant from a nursery that sells natives. However, all the fuss is worth it. Butterflies love Matilija poppy, it is truly spectacular, and it requires next to no care or water once established.
The California marigold (Tagetes lemonii) is another striking native that attracts butterflies. I first noticed this plant growing out of a crack in a Berkeley sidewalk a couple of years ago, and since then I have seen it everywhere. It is a shrub-like perennial, with golden-orange flowers and dark blue-green pointed leaves that smell like a combination of citrus, lavender and mint. It needs low to moderate water and looks wonderful with red poppies and blue salvia.
Mock orange (Philadelphus lewisii) is a native shrub that is covered with sweet-smelling white blossoms that butterflies can't resist. It is drought tolerant.
Many flowers that lure butterflies can be planted from seed. Try native milkweeds if you want Monarch butterflies in your yard. The showy milkweed (Asclepius speciosa) and Mexican whorled milkweed (Asclepius fascicularis) like the sun and, again, need little water. The purple coneflower (Echinacea) and sunflower (Helianthus) are also good choices, as are native yarrows (Achillea multifolium californicum and Achillea multifolium rosea).
Cosmos and zinnias are also easy to grow from seed and are good choices for attracting pollinators. Their flowers are of differing heights, so there is lots of movement from the butterflies as they consume nectar.
To create a true habitat, grow these plants in masses, not in isolated clumps. Make sure to have water nearby, as butterflies get thirsty. While I can't guarantee a visit from Lewis Carroll's bread-and-butterfly (last seen in Through the Looking Glass), many other varieties will enjoy your efforts, and you will love watching butterflies drift around your garden.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.