As you meander along the east side of the Santa Cruz Riverwalk, you have likely noticed the sea of blue, pink and white landscaping flags covering the riverbank between the Soquel Avenue and Laurel Street bridges. You may have wondered, “What are these flags for?” or perhaps, “Do the different flag colors mean anything?” Well, this month we are happy to answer BOTH of those questions and more.

What are the flags for?

Every flag you see marks a native plant! From November through March of every year, CWC hosts a variety of private and public River Health Days where volunteers like you help plant new native species that support a healthy river ecosystem. This winter, we’ve worked with 420 volunteers of all ages to plant over 1,900 individual plants representing 20 unique species. These plants provide a variety of ecosystem benefits like shade, erosion control, water filtration and pollinator habitat.

Every plant that goes into the ground receives it’s own individual flag. At this stage of their life, these plants are termed “seedlings.” They are quite small, ranging from the size of your fist to the size of a 1-gallon milk jug. As winter transitions into spring, you can watch these plants grow, reaching taller toward the sky and expanding outwards along the ground. However, sometimes native plants don’t grow as fast or as tall as surrounding vegetation, making them easy to miss. Brightly hued flags help us locate each individual native plant to be sure it receives the care and attention it needs to grow and thrive. During the dry season, CWC staff and volunteers regularly visit the site to remove competing weeds and provide native plants with water.

But wait, there’s more! CWC also studies native plant survival. In the late fall, CWC staff and interns visit each flag to see whether the corresponding plant has survived. If a plant dies or gets eaten (many rodents view our plants as tasty snacks!), the flag lets us know that there once was a native plant in that location. Each flag is labeled with the plant name, an identification number and the planting month and year for easy identification.

Survival monitoring helps us identify which native species really thrive along the lower San Lorenzo River. We use the information to refine and update the plant species we purchase each year, prioritizing the native species that survive the best, grow the fastest and successfully reproduce on their own. These characteristics accelerate the recovery of habitat benefits for wildlife and the scenic quality of our Santa Cruz Riverwalk park system.

For example, last year we found that Pacific Aster, California Beeplant, Dudley’s Sedge and Purple Needlegrass all had a survival rate of 50% or better, making them good bets for planting in future years. Similarly, looking at multiple years of survivorship data shows us that Pacific Blackberry, Coyote Brush, Black Sage and Hooker’s Evening Primrose are species that can persist over multiple years, making them strong investments.

Do the different flag colors mean anything?

Yes! Blue flags represent native plants that were planted during this current winter: November 2019 to March 2020. Pink and white flags represent native plants that were established in the two previous winters, 2017-2018 and 2018-2019.

Will the flags be removed eventually?

Yes! We remove flags when and if a native plant dies. We mark the plant as “perished” in our survival record and we remove the flag so it does not become litter. We also remove flags once a native plant has been firmly established for two or three growing seasons. At that stage, we consider the plant to be a permanent member of the riverbank community. We also remove and replace flags that are looking tattered. Repeat exposure to sun, wind and rain can cause flags to rip and stakes to rust, so we keep a regular eye out and swap out flags when necessary.

We will leave you with one other fun flag fact: If you look carefully at the back of some flags, you may find someone’s name or a cute hand-drawn picture. Many volunteers and students opt to personalize their plant flags to commemorate their hard work. Take a peek next time you are walking, rolling, or riding by and see if you can find one of these limited edition flags!

Thank you to Central Coast Wilds for providing all of the wonderful native plants we utilize in our habitat improvement site. Thank you, also, to the Santa Cruz Parks and Recreation Department and Santa Cruz Public Works Department for supporting this work!

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