Innovative Irrigation

This vertical garden caught my eye at Persimmon Place, which is a new shopping center that opened in 2015. It is located close to the Dublin/Pleasanton BART station, and across the street from the Hacienda Crossings center.

Vertical garden at Persimmon Place in Dublin, CA

Several store fronts, including HomeGoods, sport substantial trellises on which containers are mounted. A drip irrigation system waters the plants, using Dublin’s gray water system. This is a really innovative idea, and quite attractive.

Containers are mounted on the trellis

I wonder how well the container plants will do in the hot, inland climate, and how much maintenance the drip irrigation system will require (speaking as one who periodically replaces emitters in my own drip system). The containers provide an attractive green cover, while vines start growing from below. I’ll check on progress periodically, and let you know how sustainable this hanging garden idea is.

Gray water is delivered to containers via drip irrigation

Birds and Bees – Pollinators

Without the ability to move about freely, plants are presented with a courtship challenge. Luckily, they are equipped with some clever strategies to ensure pollination. These strategies involve relying on creatures that have locomotion – enter the birds and the bees (and a host of flies, butterflies, beetles as well).

Plants employ various tactics to attract their pollinators. Some use brilliant blossoms with visual cues such as colors, patterns, or ultraviolet wave lengths. Others use fragrances ranging from intoxicatingly sweet to those that resemble dung or rotting flesh.

Pollination of a Dandelion by a bee, carrying pollen on its body. Photo by: Guérin Nicolas

Pollinators respond to these enticements, and are rewarded with nectar. As pollinators crawl around the plant feeding on nectar, or probe for nectar, they drop off pollen collected from a previous plant, and pick up new pollen, ensuring cross pollination. Some pollinators are general – they visit many plant species. Other are very specific, such as some humming birds or butterflies that visit only a certain type of plant.

Rufous Hummingbird (''Selasphorus rufus''). Photo by: Dean E. Biggins (Fish and Wildlife Service)

Even the elements are involved in pollination. Plants, such as the oak, are pollinated via pollen born on the wind; other plants via pollen riding on liquid. This symbiotic relationship between plant and pollinator is key to the success of both.

Learn More:

• Botany for Gardeners, by Brian Capon (Timber Press 2005). See Part V Reproduction, Chapter 9, “From Flowers to Fruits”.
• Pollination and Fertilization, derived from Pollination and Fertilization, by Robert Bear and David Rintoul, for Open Stax, Rice University (Creative Commons).

What's Blooming in February?

For a few months this year, we’re taking a look at what is blooming, month-by-month here in the San Francisco Bay Area. These are not necessarily native plants, but plants or trees that are at home in our Mediterranean climate. They enliven the landscape with their early blooms.

Because of El Niño, we are having a wet and warm winter. After a long stretch of rain, followed by several weeks of warm, balmy weather, many trees and plants are starting to bloom. Some specimens may be blossoming a little ahead of their usual schedules, and some may be putting on an extravagant show to ensure reproduction after a four-year drought.

Prunus spp. in Oakland, CA

Rosmarinus officinalis in Dublin, CA

Along Highway 13, the Acacia are in full golden bloom; and along Interstate 580, through San Leandro, the naturalized Prunus are starting to bloom. I think I even spotted a Ceanothus with an early wash of blue flowers emerging. In Dublin, the Prunus are surprisingly late, but the Rosmarinus that is used for street planting is awash in indigo blooms. Closer to home in Oakland, the Helleborus is still producing flowers; the Camellias are going strong; and the Muscari are starting to amass. What a show!

Helleborus spp. in Oakland, CA (can you name those flower parts?)