2014 East Bay Open Garden Day: Potomac Waterworks

The third and final garden we visited during the Garden Conservancy’s East Bay Open Day was Potomac Waterworks in Oakland. Located on a small 6,700 sq.ft. lot in a quiet residential area, it was completely differently from the other two gardens we’d seen earlier in the day. While the other two fell in the “estates” category, Potomac Waterworks was decidedly more modest (the origins of the house go back to a 1920s cottage). However, the small square footage doesn’t take anything away from the impact of this garden. It is living proof that “size isn’t everything.”


Since the property slopes away from the street level, we had a great view of the front garden from up above. It became immediately apparent that the homeowners had opted for a subdued color and plant palette. With the exception of a few flowering plants in the backyard, the colors green and purple reigned supreme, resulting in a lush and tranquil landscape that seemed to invite meditation and hushed conversation. This is a very much a garden for adults, not for children.

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Layers of purple and chartreuse accent the path to the backyard. I loved the soft and billowy effect provided by smoke bush (Cotinus coggygria ‘Royal Purple’), Japanese maple (Acer palmatum, various cultivars) and Japanese forest grass (Hakonechloa macra ‘Albostriata’ and ‘Aurea’). 






As was the case in the first garden we’d seen that day, Potomac Waterworks was dotted with pieces of outdoor art. However, they were more abstract than representational.



As serene and inviting as the front garden was, the real magic was waiting in the backyard. This stunning mayten tree (Maytenus boaria ‘Green Showers’), a South American native that is seen far too infrequently in our corner of the world, set the mood.


“Water” is the name of the game here. Potomac Waterworks is not only the moniker of this garden, it is also the name of homeowner Paul Cowley’s company. Cowley has been designing and building water features and pond systems for 35+ years, and this garden is a splendid showcase of design techniques and materials. Lest you think a garden like this flies in the face of the drought here in California, water is very judiciously used and recirculated. In addition, a 1,500 gallon storage tank (cleverly hidden; I wasn’t able to spot it) holds rainwater collected from the gutters of the house.


This garden has it all: from a water wall, bog and stream to a koi pond. Water-loving plants such as dwarf gunnera (Gunnera magellanica) grow in lush abundance along the side of the stream.

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I was thrilled by the jungle-esque verdure of the backyard, but I’m not sure I’d be able to reliably navigate between the gaps in the stepping stones after a couple of margaritas. (Yes, that is water between the steps.)


Elsewhere in the backyard it was easier to find your footing. This combination of grasses, flagstone and blue pebbles was sheer perfection in its simplicity and restraint.


Looking back at the house, you can see how shockingly green this garden is. Not a common sight these days in water-starved California.


Arguably the most beautiful spot in the backyard is the koi pond. It is not large, but true sanctuaries never are.



It may be hard to believe, but there are more than 18 Japanese maples on the property!


A rare splash of color from Arctotis ‘Pink Sugar’ and Geranium ‘Tiny Monster’:


A garden folly with a tin roof and a mirror front lends a decidedly Japanese flair to the far corner of the backyard.


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More art is tucked away in the very back. The corrugated sheet metal fence panels are something I’ve always wanted to try in my own backyard.


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I’ll leave you with a design idea I want to try: smooth blue pebbles in varying sizes placed on top of four concrete blocks surrounded by lush grasses.


I’ve already acknowledged the contributions of Paul Cowley to this garden. His wife, Robin Cowley, is a textile artist whose vision is very much evident in the garden’s plant palette.

This was the only garden where we received a detailed write-up about the garden as well as a plant list. I really appreciated all the information, and I wish all gardens that are part of the Open Days program did that.




  1. I would have enjoyed this but I was otherwise engaged for the weekend. No Marin for me this weekend either, hopefully you will fill us in !

  2. All the gardens you have featured are inspirational Gerhard, this one more so due to its more 'realistic' size. Superb water garden and nice to see a spot of koi there :)

  3. Really nice garden. Thank you for the tour.

  4. I love how this garden "flows." They've certainly learned a lot of design lessons from water.


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