March 2012 Plant Profile: Two members of the family THYMELAEACEAE

March 10th, 2012 by Soest Gardener, Riz Reyes

I had a hard time deciding on just one plant for the month of March and I was able to narrow it down to two highly notable species and since they happen to be in the same family, I figured I’d mention the family as an excuse to have two plants this time around.

One of these plants many of us are familiar with because of it’s remarkable winter fragrance. Daphne odora. The other one is more familiar to collectors and is not as readily available, but just as dramatic and also wonderfully scented. That plant is Edgeworthia, the Chinese Paper Bush.

Both are members of a family that’s difficult to really define as there aren’t any very obvious diagnostic traits to identify it. In Landscape Plant identification, however, it’s a family known for woody shrubs producing very fragrant winter blossoms. They also have smooth bark and fibers that make them valuable in quality paper making.

First of, let’s discuss the ever popular Daphne odora. It is, by far, the most intoxicating scent in the winter garden. It has a very heady perfume and some are reminded of the children’s cereal, Fruit Loops, when they come close to admire it! The most common selected cultivar of Daphne odora is ‘Aureo-marginata’, basically implying the variable gold edges on the foliage. This species is evergreen, but ‘Aureo-marginata’ tends to be sprawly and have a poor growth habit. A newer selection called ‘Zuiko Nishiki’ looks to be a more promising cultivar with a better growth habit that’s more upright and the foliage appears cleaner, refined, but lacks the gold edge.

Common Name: Winter Daphne
Location: CUH-Fragrance Garden, Miller Library/Merrill Entrance
Origin: China/Garden Origin
Height and spread: 2ft. high and 4ft. wide.
Bloom Time: Winter

Edgeworthia chrysantha has been a much sought after collector’s plant for years, but it’s becoming more readily available. It has a really architectural look to its multi-stemmed habit and light, cinnamon colored stems. It makes a rounded shrub with lush foliage during growing season as it begins to set buds for the following winter’s blooms which are a deep creamy yellow and possess a fabulous scent. They can be finicky to get established. Make you you choose a spot with sun/part shade, and it benefits from a protected location as well as it’s not as hardy as the Daphnes here in the Pacific Northwest. Rich, well drained soil is a must along with regular irrigation during the summer and fall while buds are setting and avoid moving it around as with most daphnes, mature specimens will sulk if transplanted.

A wild form of Edgeworthia chrysantha

Common Name: Chinese Paper Bush, Yellow Daphne
Location: CUH-Fragrance Garden, Miller Library North beds
Origin: China
Height and spread: 6ft. high and 6-7ft. wide (usually smaller)
Bloom Time: Winter

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Harbinger of Spring in Seattle – Early flowering cherries on Azalea Way!

March 8th, 2012 by UWBG Horticulturist

Cherry photoMost visitors experiencing the beauty of our historic Azalea Way flowering cherries from now through May probably have no idea of how intensive maintaining their health and prolonging their longevity truly is for the UW Botanic Gardens horticulture staff.   Just ask our Integrated Pest manager, Ryan Garrison. Ryan with staff support spends many a day throughout the year monitoring and controlling the numerous diseases and insect pests our 175 plus cherries are prone to suffer from. Our rainy climate doesn’t help one bit either, especially when dealing with our most notable disease during blossom time;  a fungus known as Cherry Blossom Brown Rot. Yucko!  The good news is any new cherries we plant need to show a reasonable level of resistance. The not so good news is many of our older earlier bloomers, the ones extremely susceptible to the brown rot fungus,  need to be protected with fungicide applications during their bloom period.  As with all of our pest issues, we start with cultural and mechanical control efforts before resorting to chemical controls. The following Integrated Pest management (IPM) program discusses our best management practices for the control of blossom brown rot.  If you are interested in planting cherries for your home garden, I’ve included a list of cherries recommended for our PNW climate, all have good to excellent resistance to blossom brown rot.

Cherry Blossom Brown Rot - causal fungal agent known as Monolinia fructicola. The fungus overwinters on infected twigs and dried fruit on the tree or ground.  The fungal spores are spread in the spring by wind and rain through the blossoms, causing twig dieback.  As part of the UWBG IPM program, moving toward our goal of eliminating the use of all synthetic pesticides is our ultimate goal.

IPM relies on many strategies to manage plant health care. 

  • Proper ID of the pest and its life cycle
  • Regular monitoring of the plants
  • The use of physical, mechanical, cultural, and biological controls
  • Chemical controls used as a last resort*
  • Least toxic chemicals used

* All spray applications are in compliance with WSDA pesticide regulations.  Sign postings are located at all entrances and Graham Visitor Center. Spray applications are scheduled based on timing and weather. We do our best to apply when public are not present. For more information, pls contact, David Zuckerman at 206-543-8008 or dzman@uw.edu

The cherries are pruned in early fall  to remove infected twigs and improve air circulation.  Tree rings are given a fresh coat of mulch in the fall to bury any infected plant material that may be on the ground.  In our Cherry Replacement program we are only using cultivars that are resistant to Blossom Brown Rot.

Cherries recommended for the PNW:

    • Prunus‘Berry Cascade Snow’
    • Prunus ‘Kwanzan’ syn. ‘Sekiyama’
    • Prunus‘Pink Flair®’
    • Prunus‘Royal Burgundy’
    • Prunus‘Shirofugen’
    • Prunus‘Shirotae’
    • Prunus‘Snow Goose’
    • Prunus subhirtella var. ascendens
    • Prunus x yedoensis ‘Shidare Yoshino’
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Are you Ready for Spring?

March 7th, 2012 by Community Programs Coordinator

I know I am! I went for a walk through the Arboretum wetlands yesterday to gather some photos and information for our upcoming spring scavenger hunt (stay tuned for more info later this month!) and it truly felt like spring. Here’s what I saw:

Thimbleberry leafing out:

Flowering Indian plum:

So many water birds:

Blooming (or ready to bloom) tall Oregon grape:

Sunshine + pussy willow buds:

Grab your friends, family or come alone and see how many signs of spring you can find. If you have kids in 1st-6th grade sign them up for our Spring Break Camp where we will be adventuring in the Arboretum and looking for (and learning about) all the signs of spring we can find.


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