- Author: Penny Pawl, UC Master Gardener of Napa County
by Penny Pawl , U.C. Master Gardener of Napa County
As I sit down to write this article, my wisteria is in full stunning bloom. No leaves are present yet, but as the blooms fade, the leaves will appear.
This plant and cuttings from it have been in my family for many years. When we first moved to Napa, we lived in a Victorian downtown and this plant was growing up the side of the house. I took cuttings from it and one went to my mother's home in Calistoga where it might still be growing. She moved to Napa and I gave her another which grew very well in her new home. I took a cutting from that plant and planned to make a bonsai of it but eventually put it in the ground against a fence in my garden.
It continues to grow and the only attention I give it is trimming it back in summer and winter. After each pruning in summer, when I take off the seed pods, it reblooms. It has bloomed up to four times in one summer. The rebloom is never as great as the first bloom of the year, but I enjoy seeing the flowers.
I also cut back any of the long stems that come out all over the plant. For all these years it has continued to grow and flower without any fertilizer, water (apart from rain) or other attention. It seems to thrive on neglect.
If you leave the seed pods on the plant, they will ripen and shoot seeds out several feet. Unless you want a forest of wisteria, don't allow these seeds to sprout.
The wisteria is a member of the pea family and is native to China, Japan and parts of North America. The seeds of Chinese wisteria (Wisteria sinensis) were brought to the U.S in the early 1800s and the Japanese variety (Wisteria floribunda) followed in the mid-1800s. Plants grown from seed can take up to 20 years to bloom so nurseries imported plants as soon as they were available.
Wisteria is considered an invasive species in most parts of the U.S., although not listed as such for California. The so-called Kentucky wisteria (Wisteria macrostachya) is not invasive. I once knew a Napa County Master Gardener who lived in a very old house with wisteria planted on one side. Over time, the wisteria spread by roots to the other side of the house. So, my advice is not to plant this vigorous plant by your house.
Asian wisterias bloom on old wood and before the leaves appear, while Kentucky wisteria blooms on new growth when the new leaves have appeared. What's known as American wisteria (Wisteria frutescens) does not have invasive tendencies. The flowers come in shades of purple, pink or fuchsia; however, purple is the most common. Some plants are hybrids and can only be reproduced by grafting. Some of the flower clusters can be two feet in length.
The use of wisteria in bonsai has been common for years. Some of the bonsai are outstanding, with huge trunks. These large specimens are usually collected by “urban collectors,” bonsai hobbyists who adopt plants when homeowners take them out.
One of my neighbors has a wisteria that has been trained into a small tree. All the side growth was removed, and one trunk was allowed to grow from which all the leaves and flowers emerged. This style of wisteria must be groomed constantly to keep the shape.
If your wisteria has not bloomed and you have fertilized it, it may be suffering from too much nitrogen. Like other members of the pea family, wisteria roots have nitrogen-fixing abilities. While related to sweet pea, wisteria is poisonous to humans and animals.
Wisteria's natural tendency is to grow upward. Depending on the variety, the branches spiral either left or right. I didn't know this, but I checked my plant and, yes, all the branches spiral one way.
Wisteria vines will grow up trees, trellises, houses or whatever they can find. They have been known to break the support they were growing on, so if you have a wisteria, keep an eye on it.
By Penny Pawl, U. C. Master Gardener of Napa County
I can feel spring in the air, so it is time to think about which unique, beautiful plants I can add to my garden. As I peruse all the new garden and seed catalogs, I need to remember not to choose any invasive plants.
Many plants in American gardens and natural landscapes have come from another country. Over time, they have really made themselves at home. If you plant them, some of these imports will take over and crowd out native plants.
In Napa Valley, volunteers have had to remove Spanish broom from a local park. Spanish broom has bright yellow flowers and can take over a landscape in a few years.
Many plants become invasive because nothing keeps them in check. The wild mustard in Napa Valley is a good example. It is beautiful but an opportunist, and here it has found perfect growing conditions.
My neighbor planted a beautiful grass with small seedpods. In a short time, the grass was coming up all over their yard. Then it moved to mine. It was easy to pull, but when a seed went up their dog's nose, they pulled the grass out.
A fellow Napa County Master Gardener had a beautiful wisteria. I love this plant and admired hers which was growing on both sides of her 100-year-old house. The vine had grown under one side of the house and come up on the other. No wonder it is on the invasive-plant list.
When my husband and I were new home owners, he planted a weeping willow. He sited it many feet from our well and our home, but its roots advanced quickly toward us. It had to go.
Another neighbor had a beautiful stand of giant bamboo in front of the home. It even bloomed one year and looked wonderful. But then it spread under the house's foundation. Bamboo has a life of it' own and is extremely invasive. In Hawaii, it is everywhere but it is not a native.
One of the most invasive plants is the wild oat (Avena fatua L.). I hand weeded an area of my yard overrun by this plant. It took time but I vanquished it. The following year it did not return, but in two years, there it was again.
I also fell in love with Santa Barbara daisy (Erigeron karvinskianus), also known as fleabane. It comes from Mexico and down the coast of South America. I planted a few small plants that very quickly took over the beds. It had to go. There are natives in the same family that are not such thugs.
The California Invasive Plant Council maintains a list of the most invasive plants in California (http://www.cal-ipc.org/ ). Although nurseries still sell them, these plants threaten natives by competing for water and nutrients. These plants include big periwinkle, English ivy, giant reed, iceplant, onion grass, pampas grass, red sesbania, Russian olive and tree of heaven. Scotch broom and French broom have pretty flowers but they cause changes in the soil and shade out natives. And they produce many seeds that birds move around.
Most of these plants were imported in the 1800s for landscape gardens. The plants decided they liked it here and have moved to many areas where they are not wanted.
If you don't know what to plant, pick a California native. Natives have evolved to thrive in our soil and climate without producing rampant growth. Because they are adapted to California, most do not need much water to survive.
- Author: Marime Burton
You may have seen it and not known what it was. I noticed what looked like a gnarled lump of old wood on the trunk of my Chinese wisteria (Wisteria sinesis) just above the soil level. It was so interesting. It seemed to have come from nowhere and was about the size of my fist. I hadn’t seen it start and I didn’t notice it as it grew. I watched and wondered for a few months ... maybe for too many months if my delay caused its tragic fate to be sealed.
I had heard of crown gall (Agrobacterium tumefaciens) and considered the possibility but my mature wisteria had never looked better than it did last spring and summer. Besides, crown gall is a pathogenic tumor with possible outcomes so dire, so negative; I didn’t want to believe the bad news. This wisteria grows on a little old out building at the back of my yard with my vegetable plot at its feet. I love it.
Two days ago on one of my frequent checks, I stopped in my tracks. Directly above me where a sturdy stem came out from the trunk was another gall. Perhaps I waited too long to decide what to do.
Crown gall is not only a disease often deadly to the host plant, its pathogens essentially poison the surrounding soil. Gardeners are advised not to plant anything in the area for up to two years- not good news for my vegetable garden.
Some sources advise against cutting off the gall because the bacteria can spread. I cut off the stem on the newer one and put it in some water with a little bleach. That recourse was not possible with the one on the trunk so I followed the UCD IPM advice to cut into healthy wood around a gall, then let the tissue dry. I cut the gall out of the trunk and put it in the bleach solution. The shears went into the bleach also. I was determined not to infect anything else!
So here’s a possible silver lining. In order to be poisonous, the bacterium must contain certain tumor inducing properties and genes necessary to transfer it to the plant cell. Many strains of the bacteria are not able to do this.
I’m counting on the possibility that my wisteria has one of them.
- Author: Betsy Lunde
As a lot of my fellow Master Gardeners know, I work for the California Department of Parks and Recreation in Benicia. One of my parks is the Fischer-Hanlon House which is attached to the Benicia Historic Capitol Park. This House has an approximate 1/2 acre garden and contains many old and unusual plants. Some were planted by the Fischer family who lived in the house starting in 1856, others by their descendents. When State Parks was given the house by the surviving members of the Hanlon family (the grand-daughters of Mr. Fischer), the state workers removed over five 1-ton truck loads of plant material (mostly living) in order to clear the garden for public viewing. In doing so, the garden lost its over-grown Victorian look and acquired a somewhat "modern" interpretation of a Victorian garden. Some of the plants and trees have survived to this day and provide gardeners, such as myself, with additional problems relating to their ages.
The first plant is the Wisteria floribunda or Chinese Wisteria. This plant
originally had a span of 20 feet on a wooden pergola which has since buckled under the weight of this huge vine. With a trunk circumfrence of over 4 feet, it stretched an additional 10 feet to strangle a petite double-flowered salmon flowering Nerium oleander as well as shooting out another 15 feet into a Schinus molle (pepperwood tree) and up 40 feet to then comeback down again to hold the tree tight, rather like ribbons wound around a maypole. Currently, with the death of the pepperwood and its needed trimming, this wisteria holds tight to the re-enforced pergola, threatening to bring the old wooden structure down to the ground.
The problem with the wisteria: how to continue restraining this massive vine to
the crumbling scaffolding while figuring out how to raise it and slip another, strudier structure under the vine and then allow it to rehang itself again has been a prickly one. This is a problem five years in the works as NO one wants to identify the person who killed the 150 plus year old vine.
A second problem of the garden is how to keep a Ficus (fig tree) from completely
collapsing to the ground. This fig, dating back at least 60 years is actually the remaining branch of the original fig. Over the years, it has taking the guise of a hortizontal tree -- propped up by 4X4s in numerous places and continuing to have up to 2 crops of delicious figs per year! A little odd this year, but due to the weather it gave 3 successive crops of figs which are continuing to ripen. Needless to say, this tree is a popular stop on the garden tour! The daughter trees that have been developing over the last 3 years have come into their own in terms of providing figs for visitors and will continue the legancy of the Fisher House figs.
Another situation for garden are the huge oleanders (Nerium oleander) which have grown up to over 14 feet. Those would include a pink single-flowering which when in bloom smells like talcum powder which last year split in half (the falling half hit the house and merely slid down the side, gently brushing 1st and 2nd story windows) and deep pinks and whites along the fence -- overgrown, but contributing greatly to the colors and textures of the garden.
Roses abound in the garden, but none such as Rosa 'Belle Portugaise' (Belle of
Portugal). This gorgous rose has elegant, pointed buds which open wide and hang down in a combo of light salmon, pink, a peachy and creamy color. Our bush is over fifty-plus years old with a coating of rather shaggy bark on the older stem parts. This rose hadn't put out a new lateral shoot in 15 years, but tried twice this past year. Unfortunately for the bush, visitors have broken off both. I'm hoping that it will try again. Since it grows on a thin arbor attached to the house, the poor thing sometimes is pruned off the roof and other times pruned off the arbor. It really has no idea of which direction to grow!
Other plants include Opuntia cacti-- huge 14 foot specimens which bloom in
bright yellows during the late summer and early fall; the Arbutus unedo (Strawberry tree) which was touted during the '60s as the perfect parking strip tree. Too bad, the "touters" didn't see this specimen at 5 feet around and 20 feet tall with its dropping fruits which splatter upon falling and creating slippery, slimy spots on brick pathways.
Unfortunately, I have little hope for the continuation of this historic garden.
As most folks are aware, the State plans to close this park OR have a
nonprofit run it. Looking around at the various old plants (and some of the
newer replacements as well), the trained eye can see the misshaping of the
specimens by "gardeners" who have not studied the various plants' growths before
clipping, heading or even topping these plants. I hope that in the future, people will volunteer or be hired who understand plant growth and behavior after I leave. Could one of those people be YOU?
To volunteer at this historic site, please call 707-648-1911 and ask for Sandy