Horticulture Blog

Horticulture Blog

Santa Cruz Island Ironwood (Lyonothamnus floribundus ssp. aspleniifolius)

Lyonothamnus floribundus ssp. aspleniifolius is a mouthful to say but there is nothing edible about this tree. Lyonothamnus is endemic to the Channel Islands of California, where it grows in the chaparral and oak woodlands of the rocky coastal canyons. (more…)

President’s Notes April 2018

Here are some of the activities in which the SLO Chapter is involved that are often missed.  Is there something here that excites you?  If so, follow your passions – get involved!

Activities in April/May 2018: (more…)

Invasive Species Ailanthus altissima


Ailanthus altissima

Britton and Brown’s 1913 Illustrated flora of the northern states and Canada Public Domain: Wikipedia

Ailanthus altissima is in the Quassia family. It is native to China. It grows in disturbed areas including riparian areas and may tolerate extremely harsh conditions. It forms dense thickets that outcompete native vegetation and reduce wildlife habitat. The female trees produce fruit at several years of age. One tree can produce 325,000 seeds or MORE annually! However, it does not produce a consistent seed bank. Tree-of-heaven also reproduces vegetatively from creeping roots. New shoots can sprout up to 50 ft. away from the parent tree. It is present in many places in San Luis Obispo County, especially riparian areas. It is difficult to control. Tarping seedlings may work. Small trees can be weed wrenched. The whole plant has to go: stump and roots. Ideally a chemical application on a cut stump should consist of 20% Garlon 4 Ultra with 80% crop oil.

Conservation Update

Our chapter wrote to the California Coastal Commission to support an appeal against the illegal approval by SLO County of a subdivision of a large lot situated is an area mapped as ESHA (Environmentally Sensitive Habitat Area) immediately adjacent to the Dept. of Fish and Wildlife’s Morro Dunes Preserve in Los Osos. The Coastal Plan specifically prohibits subdivision in ESHA. The site supports Morro manzanita, and is occupied by Coastal Dune Scrub, a rare plant association.
David Chipping

Hoover Award Honoree Marti Rutherford

Hoover Award Honoree Marti Rutherford

The Hoover Committee selected Marti Rutherford as the 2017 Honoree for the significant contributions she has made to our chapter. She has volunteered in many ways to promote the education and conservation of native flora in our county. Marti is an observant person with a true curiosity about plants and plant communities. Her interest in better knowing native plants inspires her passion for collecting seed and experimenting with propagation. The plants she grows bring her enjoyment, which she happily shares with our chapter and the larger community. (more…)

President’s Notes March 2018

President’s Notes March 2018

While volunteering a few weeks ago in the CNPS co-sponsored San Luis Creek restoration project with the City of San Luis Obispo, several of us were removing weeds and planting natives along both sides of the creek in front of the Old Mission Church. This project is now entering its third year with nearly 200 native plants placed in this scenic landscape.

While working on the creek bank a few weeks ago, I noticed a number of shoots of giant horsetail, Equisetum telmateia, emerging on the (more…)

Gardening Corner

With the lack of rain, everybody is wondering what to do in regards to irrigation. As we remember from Richard W. Halsey, our 2018 banquet speaker, California native plants generally receive rain during the months of November through April. However at this juncture, mid-February 2018, we currently have a deficit of 4 to 6 inches in rainfall. Due to this unusual lack of precipitation I’m recommending, if you can afford it, to water your oaks and other California native plantings.

A Rain Bird sprinkler puts out 120 gallons in 30 minutes, this would be equivalent to about a quarter inch of rain. At this point, you would need to water for 8 hours with a Rain Bird to catch up to normal rainfall for mid-February. Of course that would be very expensive and I’m not recommending you do that. However, any extra water that you can apply to your landscape including gray water would be very beneficial.

Until next month, Happy Gardening. John Nowak, Plant Sale co-Chairperson.

Viola pedunculata (Johnny-jump-up)

Viola pedunculata (Johnny-jump-up)

Wild (California, yellow, or grass) violet, pansy or Johnny –jump-up

This botanical illustration was created by Mardi Niles using a Micron 005 #1 Archival Ink pen and Prismacolor Verithin colored pencils on Bristol Regular paper. It will be the first of several beautiful pieces of native plant art by Mardi you will be seeing on our covers into the near future. 

Viola pedunculata is widespread throughout the coastal portion of our chapter area. It extends inland as far as there is enough moisture. Dr. Hoover reports that it is apparently absent from the desert portions of our county such as the Carrizo Plains. It is always a visible treat (more…)

Heteromeles arbutifolia (Toyon)

Heteromeles arbutifolia (Toyon)

What native plant has more name recognition than Heteromeles arbutifolia, or some times, commonly known as Christmas Berry and California Holly. It is the sole species in the genus Heteromeles. Back in the 1920’s, people in southern California were drawn to the plant because is looked like holly. Some even believe that Hollywood was named after the large concentrations of the species growing on the slopes of the subdivision. (more…)

Read the Label to Protect Our Bees

Garden Products That Might Be Harmful to Bees

BeeAction.org warns that any gardening product than contains one or more of the following compounds should be avoided if you want to protect our bees. These are Acetamiprid, Clothianidin, Dinotefuran, Imidacloprid and Thiamethoxam. (more…)

Invasive Species: Brassica tournefortii (Saharan mustard)

Invasive Species: Brassica tournefortii (Saharan mustard)

Brassica tournefortii is in the Mustard family. It is native to the desert areas of the Mediterranean region of Europe. It has expanded its distribution in the sandy soils of Los Osos, most probably spread during the sewer project, and can rapidly overtake other plants and form a monoculture. (more…)

Climate Change and CNPS

With record global temperatures, giant storms, extended tree-killing droughts, and all the other assorted disasters we are experiencing, our fears that we humans are messing up the planet are becoming true. For CNPS, we see a lot of potential threats to the flora, as if the dead oaks and Sierra Nevada pines weren’t evidence enough. (more…)

President’s Notes February 2018

I received a telephone call last month, from a US Mail carrier who works in Ventura and Santa Barbara Counties, asking for information and ideas on ways to do something meaningful in the aftermath of the Thomas Fire.  At the time, I was moved – and still am as I reflect on our conversation – by the honest, soul-searching attitude that motivated her to reach out to CNPS in the first place.  I wrote back to her about a week later with a few links to information addressing the phenomenon of fire in California landscapes.  Now a month has passed along with the tragedies in Montecito.  I wrote back to her recently with these words (below), in an attempt to shed a bit of light on the causes and consequences of living in our natural surroundings. (more…)

CNPS-SLO Banquet 2018

CNPS-SLO Banquet 2018

California Native Plant Society – San Luis Obispo Chapter

Annual Potluck Banquet

Saturday, January 20, 2018

5:30-9:30 pm


Gardening Tips for Planting California Natives

With winter on the way, now is the time for us to think about planting California native plants. When we plant in the winter, or rainy season as I like to call it, we take advantage of the moist soil conditions to help establish our plants. Plants planted in the rainy season do most of their growing underground with root development. When spring comes, they respond to this establishing period by sending out new shoot growth. By summer, they are ready for the long dry months ahead and will survive on monthly waterings. (more…)

President’s Notes December 2017


As CNPS enthusiasts, we often are out in the natural surroundings, enjoying the landscapes, breathing fresh air, and getting some exercise. Who hasn’t been out on a trail or a path lately to experience a native plant community or stroll through an oak woodland? For those of us with adventure in our blood, a trip down a trail is our passport to what we study and admire out in nature. The SLO chapter has monthly field trips to destinations around the Central Coast and beyond, where we regularly get out and observe the details of plant life. And, we find this sort of activity quite fulfilling! (more…)

Invasive Species: Dittrichia graveolens (Stinkwort)

Invasive Species: Dittrichia graveolens (Stinkwort)

Dittrichia graveolens is in the Asteraceae family. It is native to the Mediterranean region of Europe. Stinkwort is erect, growing to 2.5 feet. It typically has a conical shape but can have a round appearance. It’s sometimes confused with Russian thistle (tumbleweed). It flowers from September to December and produces tiny seeds. Stinkwort’s foliage has sticky hairs covered in resin that truly stinks and sticks to and stains skin. (more…)

Sudden Oak Death Not Found in SLO’s 2017 SOD BLITZ

Sudden Oak Death Not Found in SLO’s 2017 SOD BLITZ

Kim Corella from Cal Fire has been heading up the search for Phytophora ramorum, the cause of Sudden Oak Death (SOD). She shared the 2017 SOD BLITZ results for SLO County, noting enormous participation with 289 trees sampled! Kim wanted to thank everyone who participated in this year SOD BLITZ. She notes that we were very concerned about gathering more samples in 2017 to determine the extent to which SOD was in SLO County, and is happy to report that 2017 SOD BLITZ was all negative, Apparently the 2016 SOD BLITZ survey showed false positives. The 2017 SOD BLITZ samples were tested by two completely different DNA tests and also by trying to culture out the pathogen on specialized agar. (more…)

Announcing the CNPS 2018 Conservation Conference

Announcing the CNPS 2018 Conservation Conference


WHO: Over 1,000 attendees from California and beyond.

WHAT: Two days of pre-conference workshops and field trips and three days of scientific sessions, keynote speakers, social and arts events, and more.

WHERE: Los Angeles Airport Marriott, 5855 West Century Boulevard, Los Angeles, CA, 90045www.marriott.com/LAXAP

WHEN: Thursday, February 1, through Saturday, February 3, 2018 (pre-conference workshops & field trips January 30-31)

WHY: Whether your career centers around natural resources or you just love native plants, the CNPS Conservation Conference will have something for you. From professional skills training and scientific sessions to field trips and special events, you will have many opportunities to connect with like-minded others, while learning about current research and trends, and contributing to future plans for California’s native plants and natural habitats.

Stay tuned for details! Everything you need to know about this conference is posted at http://conference.cnps.org.  Register now!