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Caltrans Native Plantings on I-280

Here in the San Francisco Bay Area, in the past couple of years CalTrans 
has landscaped some portions of Interstate 280 with native plants.  The 
landscaping starts around the highway 85 interchange in Cupertino, where 
the freeway runs below grade through crumbly, alluvial soils of gravel 
and sand.  On the south facing hillsides in this area, purple sage 
(Salvia leucophylla) is planted at the bottom, with Matilija poppies 
(Romneya) planted further up, with toyon (Heteromeles arbutifolia) and 
redbud (Cercis occidentalis) at the top of the slope.  A good amount of 
bare soil has been left between the each plant--maybe about two yards.  
On the north facing hillsides, larger forms of ceanothus are planted as 
well.

Further north along the freeway, the plantings are in the middle strip.  
This strip is more of a slope: at the top is a concrete barrier, then 
there's a small north-facing slope of anywhere from three to twenty 
yards.  Small ceanothus cultivars are planted in the narrower sections, 
mixed in with shrubby redbud, small 3 foot mounding manzanitas 
(Arctostaphylos) and the occasional toyon.  The ceanothus and redbud have 
been spectacular over the past month.  Where the median widens, larger 
ceanothus varieties are planted, as well as Quercus agrifolia, California 
buckeye (Aesculus californica), and still more toyon.  

It's simple and effective... and eye-popping this time of year, with the 
intense blues of the Ceanothus offsetting the pinks of the redbud.  The 
plantings seem to be doing well, despite the dust and smog, and they're 
interesting to look at throughout the year with their berries and flowers.

A few weeks ago, I read that Caltrans had found that a variety of 
rambling rose was a very good match for freeway plantings where there's 
lots of ground to cover.  I recall it being described as a French rose 
(I'm not into roses by any means), but you can see a whole mess of these 
new roses on US 101 in Menlo Park around the railroad underpass.

Dan
San Jose, CA
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