Monday, February 13, 2012

UC Santa Cruz Arboretum late winter update

I visited the University of Santa Cruz Arboretum last October and I wrote three blog posts: about the South African Gardens, the Australian Gardens and bamboos and succulents. Last weekend were in the Santa Cruz area and I took the opportunity to make a return visit.

Last October many plants from the southern hemisphere were just starting to bloom. Now quite a few of them are at their peak while others (especially the banksias) have already faded. I found the variety of colors, shapes and textures to be exhilarating. Since many Australian and South African natives are too tender to reliably grow in our area, they are rather exotic and novel to me.

But before we dash off to South Africa, I want to show you some manzanitas that were in full bloom. In spite of having a reputation as posing a fire hazard because of the high percentage of volatile compounds in their wood and foliage, manzanitas are becoming ever more popular as landscaping plants in the western U.S. If we had a larger property, I would run—not walk—to buy Arctostaphylos pajaroensis ‘Brett's Beauty’, the variety in the first two photos below. The wood is almost black and has a satin gloss. I think it’s the most attractive manzanita I’ve ever seen, although the other two are close runners-up.

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Arctostaphylos pajaroensis ‘Brett's Beauty’,
an especially attractive form named after Brett Hall, the director of the UC Santa Cruz Arboretum
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Arctostaphylos pajaroensis ‘Brett's Beauty’
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Arctostaphylos viridissima ‘White Cloud’
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Arctostaphylos viridissima ‘White Cloud’
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Arctostaphylos montaraensis
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Arctostaphylos montaraensis

I did a double-take when I came across this giant coreopsis (Coreopsis gigantea) surrounded by ground-cover manzanitas, Coreopsis gigantea is anything but common, and I had just bought one at Cactus Jungle. Take about coincidence!

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Coreopsis gigantea (surrounded by a low-growing manzanita)

Leaving the California natives behind, we enter the South African Gardens. The focus here is on restios, ericas and proteaceans. While the restios don’t undergo a lot of seasonal changes, the ericas and proteaceans really come into their at this time of year.

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Erica canaliculata
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Erica canaliculata

While the South African ericas are similar enough to European heathers that they present a familiar sight to most gardeners, proteaceans have inflorescences that are completely different from shrubs typically seen in U.S. gardens. Proteas and, to a lesser degree, leucadendrons, are showstoppers. While they grow well along the California coast, they are simply too wimpy to survive in areas with anything but light frost. (For people wanting to push the limit, here is an article on growing proteaceans in Seattle.)

South African proteaceans require full sun and well drained soil. Like all proteaceans, including those from South America and Australia, they are extremely sensitive to phosphorus in the soil. Even the phosphorous in common fertilizers can damage them. Some experienced growers say that no fertilization at all is needed, others recommend very light applications of organic sources of nitrogen that are low in phosphorus (no more than 4%).

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Leucadendron laureolum
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Rhodocoma capensis (left), Leucadendron laureolum (right)
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Leucadendron salignum ‘Winter Red’ (left), Leucadendron laureolum (right)
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Leucadendron salignum ‘Winter Red’
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Chondropetalum tectorum (top),
Leucadendron salignum ‘Winter Red’ (bottom)
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Leucadendron salignum ‘Winter Red’
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Leucadendron salignum ‘Winter Red’ ablaze in the distance
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Leucadendron discolor ‘Cloudbank Ginny’
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Leucadendron discolor ‘Cloudbank Ginny’
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Leucadendron discolor ‘Cloudbank Ginny’
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Leucadendron discolor ‘Cloudbank Ginny’
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Protea neriifolia
                                                                                                                                                
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Protea neriifolia (left), Protea ‘Pink Ice’ (right)
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Protea neriifolia
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Protea obtusifolia
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Protea obtusifolia
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Protea compacta × magnifica

Originally, I wasn’t going to post more photos of restios since they look about the same as they did in the fall. However, since I have a weakness for these unique rush-like plants, I’m going to sneak in a few images.

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Rhodocoma capensis
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Elegia capensis
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Elegia capensis
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Chondropetalum tectorum

Moving from the South African to the Australian Gardens, the first thing I noticed were the banksias. They had been in full bloom when I visited in late October, and now they are heavy with seed “cones.” While not the same feast for the eyes as the flowers, the cones have their own kind of beauty and definitely offer a lot of visual interest.

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Banksia marginata

Other Australian protaceans were going strong, especially the grevilleas. The genus Grevillea contains over 360 species native to Australasia. Hybrids with large, showy flowers (typically crosses between Grevillea banksii and Grevillea bipinnatifa) are particularly popular.

The best-known of them is ‘Robyn Gordon’. There’s an interesting story attached to this hybrid, and it speaks to the obsessive nature so common to plant collectors:

It is a chance hybrid that arose in the garden of the late David Gordon of Myall Park, Glenmorgan, Queensland. David Gordon was a plant collector with an extensive collection of Grevillea species which (according to legend) he planted in alphabetical order by species. This meant that the Queensland species, Grevillea banksii, was planted in close proximity to the Western Australian species, G. bipinnatifida. A plant that was later to become the cultivar "Robyn Gordon" (named after David and Dorothy Gordon's daughter) arose by chance near these two parent species. (Source: ANPSA)

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Grevillea banksii × bipinnatifa ‘Robyn Gordon’
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Grevillea banksii × bipinnatifa ‘Robyn Gordon’
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Grevillea banksii × bipinnatifa ‘Masons Hybrid’, very similar to ‘Robyn Gordon’

Bottlebrushes (callistemons) are common landscaping shrubs here in California. When I saw the next plant, I thought it was a callistemon, but it turned out to be a relative called Kunzea baxteri. It’s a large shrub with interesting foliage and stunning flowers.

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Kunzea baxteri (left) with an unidentified grevillea on the right
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Kunzea baxteri
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Kunzea baxteri

The most arresting sights in the Australian Gardens were the acacias (or “wattles,” as they are called down under) in full bloom. Just take a look at this tree! We saw many more acacias all over town, especially along Highway 1.

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Acacia baileyana
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Acacia baileyana
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Acacia baileyana

Most eucalyptus weren’t blooming yet. This one was, Eucalyptus caesia subsp. magna, and its flowers were magnificent.

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Eucalyptus caesia subsp. magna

I also noticed several smaller plants I’d never paid attention before, probably because they weren’t in bloom then. The first one is Pimilea ferruginea ‘Bon Petite’, a small shrub with interesting stacked leaves reminiscent of certain crassulas (no relation; Pimilea is not a succulent).

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Pimilea ferruginea ‘Bon Petite’

The other was Tetratheca thymifolia, a small shrub covered with light purple flowers. There were three or four Tetratheca growing in a clearing surrounded by towering eucalyptus trees. In the photo below you can see the eucalyptus bark that carpets this area.

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Tetratheca thymifolia

On my way back to the car, I swung by the Succulent Garden, always a favorite because of its location on top of a hill. On a clear day you can see the Pacific ocean.

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Succulent garden

I found a nice clump of Aloe arborescens in bloom…

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Aloe arborescens

…and an Aloe reitzii sporting deep salmon coloration. I’ve never seen this color on an aloe before. My Aloe reitzii is always green even though it gets a fair amount of sun.

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Aloe reitzii

Two agaves were standouts as well: An Agave parryi growing amidst Aloe nobilis and a ground-cover manzanita…

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Aloe nobilis with Agave parryi

…and the most spectacularly colored Agave filifera I’ve ever seen. The symmetry of this agave was astounding.

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Agave filifera

Like many visitors, I stopped by Norrie’s Gift Shop before I left. They have a very nice selection of Australian and South African plants as as well as California natives (at least five species of manzanita, for example) and some succulents.

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Plants for sale at Norrie’s Gift Shop
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Plants for sale at Norrie’s Gift Shop

UC Santa Cruz Arboretum is strapped for cash and Norrie’s is an important source of income for them. You know how much I hate to buy plants, but I forced myself to purchase a couple to help out :-).

Seeing how I love a challenge, I selected a Leucadendron salignum ‘Winter Red’ (the beautiful red variety shown in several photos in this blog) and a Grevillea ‘Superb’, a Grevillea banksii × bipinnatifa hybrid that is supposedly hardier than ‘Robyn Gordon’. I’ll let you know next winter how they fared!

8 comments:

  1. Another enjoyable tour. Really had to twist your arm to bring home one of those amazing Grevillea. Tose photos are superb!

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    1. Thanks, Nat! I've wanted a grevillea for a long time. I'm leaning towards putting it in a large container on the backyard patio so we can enjoy the flowers. In Australia they bloom year round; maybe they will here, too, if I pamper it?!

      Do read this article about growing proteas in Seattle. A lot of it might apply to your location.

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  2. Wow Wow Wow...too much beauty! Love that you linked to one of Ian's articles, he really knows his stuff.

    As you'll see if you read my post tomorrow I bought a Banksia (fingers crossed) from him at the NWFG Show, where I also bought a couple more Grevillea. What I wouldn't give to grow Leucadendron and Protea though.

    Thank you for all of the drool-worthy photos, that black barked Manzanita is amazing!

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    1. Loree, excellent article. Here's the link for everybody else: Danger Garden.

      The biggest problem I foresee with my leucadendron and grevillea is drainage. Our native soil is relatively heavy clay. I'll add lots of pumice and will plant on a mound.

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  3. Wow. Some really great photos -- reminds me that Spring is a very good time to visit California. I still love the Elegia capensis, and that Grevillea x 'Robyn Gordon' -- just an amazing flower!

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    1. Time to plan a trip! I'd love to meet you in person.

      The restios at UC Santa Cruz are spectacular. The conditions there must be perfect.

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  4. Superb photos Gerhard, so many beautiful Southern Hemisphere plants there! I was just admiring a table full of Leucadendrons earlier which are all not hardy enough in our garden (has to be kept in a pot), as well as some healthy restios.

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    1. I'd love to live in Santa Cruz. They can grow all these amazing plants from South Africa and Australia AND succulents AND bamboo AND just about anything else. And they've got the Pacific Ocean.

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