Category Archives: Weather

Marking the Passage of Time

Summer is slowly showing itself on the island and the change of seasons can be seen in the blooming gardens.

A section of the main road, as visitors walk from the dock to the cell house is affectionately called the ‘fern wall’, even though in summer there is no evidence of ferns anywhere. The granite blocks that form this retaining wall was built in the early military days and was softened by moss and ferns that came to the island likely as spores in the imported soil.

The fern wall in 1924. San Francisco library photo

As the winter rains cease, the native fern, Polypodium californicum turns a golden  brown and then go dormant. The fern wall undergoes a dramatic change from lush green to vivid pinks as the Jupiter’s beard, Centranthus ruber, bursts into the season. At the base of the wall is a collection of Pelargonium that are survivors from the prison days – ‘Brilliant’, ‘Mrs. Langtry’ and P. quercifolium that add to the hue of pinks.

Fern wall in the spring. Photo by Shelagh Fritz

Fern wall in the summer. Photo by Shelagh Fritz

To be accurate with historic photos of this wall, last year, we planted plugs of Persian carpet, Drosanthemum floribundum in the cracks of the granite blocks that will eventually cascade down the wall. With living walls being the current trend in gardening, this wall on Alcatraz was way ahead of its time.

The wall in the 1940s. Photo by Joseph Simpson

When the fog rolls in, the intent of the original gardeners to create cheerfulness on a barren island must have been no easy undertaking. I also cannot help but wonder if the inmate gardeners marked the passage of time with the changing blossoms.

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Tool shed has a new look

On the west side of the island, tucked under the New Zealand Christmas tree, Metrosideros excelsa, is the historic tool shed, originally built by inmates in the 1950s. The tool shed has a million dollar view towards the Golden Gate Bridge and the Pacific Ocean beyond. Without a doubt, this view was a constant reminder of a world beyond the reach of the inmates that worked in these gardens.

View of the Golden Gate Bridge and the Marin Headlands. Photo by Shelagh Fritz

The toolshed in 2009. Photo by Robin Abad

The tool shed, like the gardens, was abandoned in 1963, and could not escape the weathering effects of Pacific storms and the relentless summer winds and salt air. The tool shed was repaired by the National Park Service in the late 1970s and again by garden volunteers in the spring of 2010 with help from the National Park Service maintenance team. The tool shed was in a bad state of repair with the roof falling in and most of the wood structure rotting away. The cement block base walls were still in fair condition and only needed minor patches. Just like the inmates had used scrap lumber on the island in the original construction, we scouted re-use stores to find a door, suitable windows, and flashing for the roof. This past month, garden volunteers applied primer and a fresh coat of ‘Presidio White’ paint to finish up the restoration.

Garden volunteers applying the final coat of paint. Photo by Shelagh Fritz

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March Showers bring Summer Relief

Water is a precious resource around the world and especially in California where we receive our year’s supply between November and April. This past week was especially rainy and residents of the Bay Area are probably ready for a few sunny days.

This year year to date, downtown San Francisco has received 18.11 inches of rain, just above our normal for the entire year! With another month of winter rains to come, our reservoirs will be full to capacity for the dry summer months.

The rainwater catchment system on Alcatraz is nearing capacity with its current levels at 80% full. This is the second year the catchment has been in use and supplies enough water to meet the irrigation needs of the gardens for one year. Even though we choose drought tolerant plants, everything appreciates a drink to perk themselves up.

I ventured out to the west side of the island during one of the downpours this past week to see the system at work: water catchment. Seeing the rain water flowing easily from the downspout into our basins was very satisfying, knowing that each drop will be used by the thirsty plants to get through the summer months.

Even though the rain can be cold and unpleasant, the dramatic skies provide countless photo opportunities – so grab your camera and get outside.

Alcatraz Island in the early morning light. Photo by Shelagh Fritz

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Weedy and wild edibles

Volunteers took advantage of the sunny weather this morning to weed wild radish, Raphanus raphanistrum, on the southern facing slope in front of the cell house. This annual weed, a member of the mustard familyBrassicaceae – has naturalized in North America from its native Eurasia.

Radish weeds covering hillside. Photo by Shelagh Fritz

This overgrown section of the slope was stabilized in 2007 with waddles and jute netting but has since become overgrown with radish, Lavatera and oxalis. This is the first year that we are attempting to control the radish. Our intent is to reduce the number the weed seeds so that in future years, this slope will be planted with the Persian carpet, Drosanthemum floribundum that was historically planted on this slope during the 1920s.

Slope stabilization in 2007. Photo by Shelagh Fritz

The radish is just beginning to establish itself for the summer by sending its long taproot deep into the soil to find moisture. Volunteers took on the challenge of pulling the entire root, otherwise the plant will continue to grow. Either it was the hard work or the scent of fresh radish but like other radishes, these roots are edible and soon the volunteers were nibbling at the roots. The flowers are also edible and are easily identifiable with four petals ranging in color of pale yellow, apricot, pink and white. When considering consuming any plant from the wild, it is vital to be confident that you have positively identified the plant.

Tim holding the edible radish root. Photo by Shelagh Fritz

Flowering radish. Photo by Shelagh Fritz

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Alcatraz Island Hardiness zone

The chilly weather this week has many Californians bundled up inside. The temperature on Alcatraz is moderated by the San Francisco Bay and we are very fortunate to be frost free; but the dampness, wind, and fog can still make any time of the year feel cold. San Francisco is in United States Department of Agriculture (USDA) Hardiness zone 10 and zone 17 to residents of western U.S.A. who refer to the Sunset climate zones.

The USDA revised the plant hardiness zone map in 1965 and again in 1990. The 11 zones aim to show the lowest temperatures that can be expected. Plants are rated for which minimum zone they can survive in.

Sunset Magazine created a 24 zone climate map for the thirteen Western states. These zones are much more detailed and precise as “they factor in not only winter minimum temperatures, but also summer highs, lengths of growing seasons, humidity, and rainfall patterns to provide a more accurate picture of what will grow there.”(www.sunset.com)

Micro climates exist even on a small island like Alcatraz. This week, with the wind coming from the north, there are a few gardens that volunteers and staff gravitate towards on chilly days. The southwest facing inmate gardens that usually get the brunt of the summer winds and fog are the perfect gardens to bask in during the winter sunshine. The low winter sun casts a chilly shadow on the east side of the island for most of the day.

West side Toolshed Terrace gardens in sunshine. Photo by Shelagh Fritz

East side of the island in mid-day shade. Photo by Shelagh Fritz

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