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Thursday, November 9, 2017

Plant of the Month (November) : California wild rose – Rosa californica

California wild rose (Rosa californica) - Mother Nature's Garden of Health

No, wild roses aren’t blooming in November.  Our weather’s been crazy, but roses are still a summer treat.  But the Rosa californica in Mother Nature’s Garden of Health has colorful fruits (hips) right now.  That why we’re featuring it as our Plant of the Month.  The scientific name is easy to pronounce: ROSE-uh  cal-ih-FOR-nih-cuh.

The California wild rose is the common rose of much of California, from Oregon to Baja California, Mexico.  It grows throughout the California Floristic Province (West of the Sierra Nevada Range) except in the high mountains.  There are nine or ten species of rose native to California.  Most grow in the Sierras or in Northern California – areas that get more precipitation than we do.  In the San Gabriel Mountains of Los Angeles County, the Woods’ rose (Rosa woodsii) is still fairly common.  But throughout much of S. California, Rosa californica reigns supreme.

California wild rose (Rosa californica) -
 Gardena Willows Wetland Preserve

The California rose is commonly encountered in moist places below about 6000 ft. (1800 m.) elevation.   It can still be seen along rivers and streams, in canyons and in shady woodlands throughout S. California.  It once was common on Santa Catalina Island, in the Santa Monica Mountains, and in the foothills of the San Gabriel and Liebre Mountain ranges.  It also grew along the local rivers, including the Los Angeles River. You can see nice patches of this rose in the Gardena Willows Wetland Preserve.  There’s even an early voucher specimen from Redondo Beach!

California wild rose (Rosa californica) - growth habit

Like many wild roses, Rosa californica is a clumping woody shrub. It has long (3-9 ft.; 1-3 m.) woody stems that are often many-branched.  It’s a rose, so the stems are prickly – not the big thorns of domesticated roses, but still requiring gloves to handle.  Like most roses, California rose is winter deciduous, losing all its leaves with the colder days of December or January.  And like other roses, this species is best pruned when dormant (more on this below).

California wild rose (Rosa californica) - foliage

The foliage of California wild rose is typical for roses.  The leaves are compound, with 5-7 simple leaflets.  The leaflet edges are serrated.  The color is yellow-green on emergence, becoming medium- to dark green.  If conditions are right, the leaves turn a lovely soft yellow in late fall/early winter.  The fall leaf color can be quite attractive.

California wild rose (Rosa californica) - thicket
 in Gardena Willows Wetland Preserve
Like many wild roses, Rosa californica is a spreader.  It sends up new stems by root suckering and can form dense thickets in favorable locations. Plants that get minimal water spread more slowly than those with regular water. But the nature of this species is to spread when conditions are right.   The gardener should seriously consider location when planting the California wild rose. You may want to place it where the spread is limited, or even grow this rose in a large container.  A thicket of thorny roses may not be part of your vision for the perfect garden!

California wild rose (Rosa californica) - blooming shrub

The California rose blooms during warm weather.  The actual blooming may be off and on from May through October, depending on whether the plant gets water.  A blooming Rosa californica is truly a thing of beauty.  In a good year, a bush can be literally covered in blooms. 

California wild rose (Rosa californica) - flower

The flowers are fairly typical of the wild roses. The flowers are simple – not the many-petal extravaganzas we expect from modern horticultural roses. The flowers are about 1 ½ inches (4 cm.) wide and have five pink petals, usually a medium pink, but sometimes paler or darker. Like all roses, the flowers have numerous stamens and pistils (male and female sexual organs). 

California wild rose (Rosa californica) - inflorescence
Not surprisingly, the flowers are insect pollinated (mostly by bees) and plants are self-fertile. The inflorescence (floral cluster) may have up to 20 flowers; a bouquet in a single inflorescence!  The flowers give off the heavenly scent of wild roses.  There’s really nothing quite like a wild rose on a warm summer’s day.

The fruits of all roses are fleshy, ovoid structures containing many seeds.  The hip (also called a hep) is actually an accessory fruit; it’s not formed from the ovary of the flower, but instead from other tissues.  Apples, pears, strawberries, figs and pineapples are also accessory fruits.

California wild rose (Rosa californica) - fruits (hips)
The hips of Rosa californica are up to ¾ inch (8-20 mm.) across and are a dark red when fully ripe.  The hip begins forming soon after a flower is pollinated.  The immature hips begin small and green, then progress through a firm orange stage (late summer) and finally ripen to a somewhat soft, dark red in fall.  If you live in an area with fall/winter frosts, the best time to pick the fruits is after the first frost (if the birds haven’t eaten them all before then).

California wild rose (Rosa californica) - sunny,
 dry position
Wild roses are less finicky than their horticultural cousins.  They can be grown in most local soils (except slow-draining clays) and tolerate full sun to part shade.  Plants are more shrub-like in sun; more vine-like in fairly shady conditions.  The flower color is often a bit brighter in plants that get afternoon shade.  But plants in places that are too shady won’t flower as much. 

While Rosa californica is more drought tolerant than many roses, it does best with some summer water.  Occasional deep watering – once or twice a month depending on soil drainage – is enough.  If grown in pots, water whenever the potting medium is dry at a depth of about 4 inches.  We sometimes water our pot-grown rose several times a week in hot, dry and windy weather.

Rosa californica is much less susceptible to the fungal diseases and pests that plague garden roses.  Limiting summer water to the recommended levels is also helpful. And California wild rose won’t need much fertilizer unless grown in a container.  Container-grown plants should be given several doses of ½ strength fertilizer (or half a recommended dose of time-released fertilizer) in late winter/early spring.

California wild rose (Rosa californica) - pruned
Pruning of wild roses is best done when plants are dormant.  We like to prune our pot-grown plant as we would a garden variety.  This insures healthy, new growth – and mimics the natural ‘pruning’ of grazing animals in the wilds. It also helps to tame the ‘wild’ appearance somewhat.   Some gardeners prefer to just prune out the oldest canes (and those that have sprouted in unwanted places).   Either approach is acceptable.

So why plant a California wild rose instead of a floribunda?  First, there’s the shear enjoyment of planting a species native to our area. Gardeners living near open spaces can make the environmentally sound decision of planting a native rather than a non-native rose.   All native plants, in addition to being well adapted to our climate, give us a sense of place and a link to the past.  In the case of Rosa californica, they also perfume our gardens with the scent of Old California.

California wild rose (Rosa californica) - excellent
habitat plant
California wild rose is an excellent habitat plant.  It attracts bee pollinators, including some native species.  Many rose cultivars attract few, if any, pollinators.  The plants provide armed cover for ground dwelling creatures like lizards and ground-foraging birds like White-crowned sparrows, Doves and Towhees.  And the fruits are prized food for the fruit eating birds (bluebirds, grosbeaks, robins, mockingbirds, and sparrows).

California wild rose – and other roses – have long been used as perfumes and for potpourri.   The stems are sometimes used as rims in twined basketry. And, of course, the wild roses have long been prized for their edible and medicinal uses.

California wild rose (Rosa californica) - freshly
 picked hips
Ripe rose hips have a sweet taste that’s hard to describe.  They can be eaten raw (in moderation), made into fruit leather or dried and ground to make a flavoring.  Their flavor can be extracted in vodka to make a ‘kitchen extract’ used to flavor cookies, cakes, candy, etc.  And the cooked fruits make delicious syrup, jelly, or fruit soup.  Dried or fresh fruits, as well as the petals and leaves, can also be used to make flavorful and healthy herbal teas.  For more ideas on preserving the fruits of summer see: http://mother-natures-backyard.blogspot.com/2016/08/california-gourmet-preserving-summer.html

California wild rose (Rosa californica) - making jelly
Most parts of the plant have a history of use as medicinals.  Dried petals were formerly ground and used as baby powder to help prevent diaper rash.  An infusion (tea) from the petals was also used to treat pain and fevers in infants and children. Rose hip tea is still taken for fevers, colds and sore throats.  The high vitamin C content of the hips partially accounts for its efficacy.  But rose hip infusions have also been used as a wash for skin sores, so the hips may have additional antibiotic properties.

In summary, California wild rose is a unique, useful and lovely part of our Southern California natural heritage.  It can be used as a barrier hedge or planted on hard-to-maintain canyon slopes.  It can also be planted in contained areas – even in large pots.  We hope you’ll look for - and possible use – this wonderful native rose.

California wild rose (Rosa californica)

For plant information sheets on other native plants see: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html



We welcome your comments (below).  You can also send your questions to: mothernaturesbackyard10@gmail.com


1 comment:

  1. Your articles are always so comprehensive. Thank you again for another great read.