January 2015 Plant Profile: Helleborus x ericsmithii ‘Shooting Star’

December 31st, 2014 by Soest Gardener, Riz Reyes

Helleborus Shooting StarThe first of the year starts off with a bang with a most wonderful hellebore hybrid to ring in the new year showing the first blossoms of the season. Here at the Center for Urban Horticulture, we’ve acquired quite a selection of hellebores thanks to Skagit Gardens and Northwest Garden Nursery. ‘Shooting Star’ is one that’s been under our watchful eye for its third season now and we’ve been impressed with its excellent foliage and vigor along with the early flower power it possesses in the garden. We have it growing in three different locations at the Center for Urban Horticulture and each specimen is thriving, making it a stand-out in the winter landscape.

All types of hellebores are beginning to pop up at local nurseries. Many will be in full bloom, so you can select from hybrid seed strains or clones such as ‘Shooting Star,’ which will be all identical compared to the seed-grown strains. Hellebores make wonderful container plants and can be potted up or safely planted into the garden as long as the ground is not frozen.

‘Shooting Star’ opens to a pale blush pink with just a hint of green. As it ages, it slowly turns greener and the pink is accentuated. These “antiqued” blooms last into March.

Companions: Ophiopogon planiscapus ‘Nigrescens’ (black mondo grass), Cyclamen coum, Acorus gramineus ‘Ogon’ (sweet flag), Pulmonaria hyrbids (Lungwort)


Genus: Helleborus
Species: × ericsmithii
Cultivar: ‘Coseh 790’   Shooting Star  USPP #22424
Common Name: Lenten Rose
Location: Douglas Parking Lot, Soest Garden South Slope, Miller Library North Foundation Plantings
Origin: Garden Origin
Height and Spread: 10-12 inches high and about 1.25 feet wide
Bloom/Fruit Time: Late December-early March





December 2014 Plant Profile: Schlumbergera

December 1st, 2014 by Soest Gardener, Riz Reyes

Christmas Cactus flower close upLooking  nondescript throughout most of the year, the so-called “Christmas cactus” puts on a tremendous show as the holidays arrive in November and December.

As part of the Cactus family, they are actually epipthytic plants (similar to air plants) that grow on rock crevices and trees in the wild and require a well drained potting mixture and specific dry rest periods in order to initiate flowering when grown as a house plant.

Most receive a Christmas cactus as a blooming gift for the holidays. They can be enjoyed anywhere in the home where it receives bright, indirect lighting, humidity and very sparse (about once every two weeks) watering.  Following the tremendous floral show, plants will rest and watering is greatly reduced further until about March or April when they can be re-potted if desired (although they prefer the tight confines of being potbound in a small container). New growth resumes and regular watering and fertilizing (all purpose fertilizer is fine) can take place (once every week or two). They can also sit outdoors up against the house protected from direct light during the summer and can be treated like other container plants.



To initiate flowering again:

Water is withheld as days get shorter and temperatures begin to drop. They need a cycle of normal daylight and then  complete darkness for 12-14 hours for about 6 weeks. All this usually begins around September into October where you can either start bringing them indoors in a room that will be completely dark for that period of time or they can stay outdoors and make sure street lights aren’t disrupting this dry/dark period. If temperatures are expected to drop below 55F, then the plants should be brought inside.

After this treatment, buds should have formed and regular watering and care (once every one or two weeks) can resume as they begin to open and flower.

Christmas Cactus habit

A bright, deep pink Schlumbergera begins to show off amongst the tropicals just as you enter the Douglas Conservatory.


Genus: Schlumbergera
species: × buckleyi (T.Moore) Tjaden = S. russelliana × S. truncata; S. Buckleyi Group is the most common.
Cultivar: Assorted named cultivars exist, but often offered by color only
Common Name: Thanksgiving/Christmas Cactus, Zygo-Cactus
Location: CUH Douglas Conservatory Entry
Origin: Wild species originate from SE Brazil
Height and Spread: 1.5-2′ high with stems that can drape 3-4ft. long
Bloom/Fruit Time: November-early January







November 2014 Plant Profile: Callicarpa dichotoma ‘Early Amethyst’

November 3rd, 2014 by Soest Gardener, Riz Reyes

IMG_7871Beautyberry is starting to put on quite a show and we have a species that isn’t common in Pacific Northwest Gardens. Callicarpa dichotoma is widely known on the East Coast and thrives in their summer heat and humidity. Having had an exceptionally lengthy summer here, our plants of ‘Early Amethyst’ look the best they’ve ever looked in the three years since they were planted out as small 1 gallon pots.

Combined with consistent moisture in full sun, they’re dripping in hot purple pink and look absolutely stunning in the autumn landscape! We hope the foliage has a chance to color up before a hard frost comes. Meanwhile, they are a sight to behold

Genus: Callicarpa
species: dichotoma
Cultivar: ‘Early Amethyst’
Common Name: Beautyberry
Location: CUH Sidewalk Entry
Origin: China, Japan, Korea, Vietnam
Height and Spread: 4′ high x 4-5′ wide
Bloom/Fruit Time: September-frost



Growing with the bright gold, moisture loving Acorus gramineus 'Ogon'

Growing with the bright gold, moisture loving Acorus gramineus ‘Ogon’


C. dichotoma ‘Early Amethyst’ with Persicaria amplexicaulis ‘Taurus’

October 2014 Plant Profile: Amaryllis belladonna

October 1st, 2014 by Soest Gardener, Riz Reyes

IMG_7256A large indoor bulb that’s forced to flower in time for the holidays is often what gardeners think of when we say “Amaryllis.”  Those large, almost dinner plate-sized flowers are actually the genus Hippeastrum. The true Amaryllis, depicted here, is a fall-blooming plant. Though its growth habit is similar to Hippeastrum, it can be grown outdoors in the Pacific Northwest

Native to South Africa, they thrive in Mediterranean type  climates with full sun and well drained soil and are best left undisturbed once planted as they can take several years to flower from bulbs that are regularly available for planting in the spring.



Genus: Amaryllis
species: belladonna
Common Name:  Naked Ladies
Location: McVay Courtyard
Origin: South Africa
Height and Spread: 15-18″ tall stems and forms clumps 3-5ft. in width over time
Bloom Time: August-October







September 2014 Plant Profile: Coreopsis Big Bang™ ‘Star Cluster’

September 4th, 2014 by Soest Gardener, Riz Reyes

Coreopsis Big Bang 'Star Cluster'Tickseed is the common name for the cheery and colorful Coreopsis. Long  utilized as a border plant in  perennial gardens, it’s often only know for its ferny green foliage and one main flush of bright yellow blooms in early summer. Now, thanks to Darrell Probst’s spectacular  breeding work on the Big Bang series, the genus has been revolutionized, with a wider range of colors with almost continuous bloom throughout the season! Skagit Gardens in Mt. Vernon, WA has sent us samples over the years to display and trial here at UW Botanic Gardens and we have them peppered around the Center for Urban Horticulture.

This stunning selection is ‘Star Cluster’. It probably has the tidiest habit of all the Coreopsis we have. It has worked very well as a edging plant because it stays fairly low and it has been in flower since June with minimal deadheading.  The color progression of the flowers is quite fascinating as it opens to a lovely cream with a crimson center and over time and as the weather cools for autumn, the center color softly blends and becomes more prominent on the entire flower.



Coreopsis Big Bang 'Star Cluster'


Coreopsis Big Bang 'Star Cluster' habit


Genus: Coreopsis
species: N/A
Common Name:  Tickseed
Location: Soest Garden Bed 5
Origin: Garden Origin.
Height and Spread: 15-18″ wide and 10-12″. tall
Bloom Time: June-Frost

August 2014 Plant Profile: Aeonium arboreum var. atropurpureum

August 4th, 2014 by Soest Gardener, Riz Reyes

Aeonium 1Succulent plants continue to be very popular amongst gardeners everywhere because of their unusual and architectural forms and thriving with very minimal watering. The Aeoniums are one of the most iconic of all succulents. Unfortunately, they are not hardy in the Pacific Northwest, but they are excellent container specimens that are actually pretty easy to overwinter if cared for properly indoors.

The key to success with any succulent is bright light, very well-drained soil and limited watering during the growing season. They respond to being fertilized on a regular basis during active growth (for us it’s June-September) and then as cold temperatures approach, they are dug up before the first frost and potted up and kept indoors where it can stay cool, but not freezing. Some growers overwinter them “bareroot” and will mist them occasionally so they don’t dry out. The more light you can give them during this pseudo-dormant period the better.

Aeonium 2

Genus: Aeonium
species: arboreum var. atropurpureum
Common Name:  Tree Aeonium, Irish Rose, Houseleek
Location: Containers in Soest Garden
Origin: Straight species from Canary Islands, but this selection may be of garden origin.
Height and Spread: 1.5ft wide to 2ft. tall (potentially much larger in milder climates)
Bloom Time: N/A for Pacific NW outdoors (but may flower later winter/early spring if greenhouse-grown)



July 2014 Plant Profile: Hydrangea integrifolia

July 1st, 2014 by Soest Gardener, Riz Reyes
Photo courtesy of Richie Steffen/Great Plant Picks

Photo courtesy of Richie Steffen/Great Plant Picks

An evergreen hydrangea?!!  You betcha!

There are very few evergreen vines for gardeners in the Pacific Northwest, but this gorgeous gem from Asia is  becoming more readily available and it’s simply one of the coolest flowers you’ll ever get to witness opening.

From plump, peony-like buds, they begin to slowly crack open, a froth of fertile flowers begin to form and over the course of a few days, a flat umbel “lacecap” begins to form. People will begin to believe that it’s actually a hydrangea!

Hydrangea integrifolia is quite slow to establish (and re-establish, as we’ve learned after moving it to its new location at CUH three years ago) and may not even flower for the first few years of its life. Once it does, it puts on quite a show each summer. Dark green, glossy foliage remains year round. It’s a clinging plant that forms aerial roots on its stems. The aerial roots attach to a rough surface such as the bark of a tree or rough stucco wall; they don’t form tendrils or long whip-like shoots that wrap around supports so you have to carefully train them until they take hold. You could also let it sprawl on the ground as a ground-cover plant in a woodland garden.

They grow best in a protected spot in the garden such as a shady north-facing wall (such as our specimen here at the Center for Urban Horticulture), but they’re also quite at home tumbling over a stone wall in full sun with regular irrigation during the summer months.

Common Name:  Evergreen Climbing Hydrangea
Location: Center for Urban Horticulture – Miller Library North Foundation Bed
Origin: Taiwan/Philippines
Height and Spread: Can get 40′ tall and about 20′ wide
Bloom Time: Late June – July

June 2014 Plant Profile: Philadelphus lewisii

June 3rd, 2014 by Soest Gardener, Riz Reyes

Philadelphus lewisii portrait 1The beginning of June boasts boisterous and abundant blooms and this native shrub is no exception. Starting in late May, an otherwise nondescript shrub begins to draw attention as masses of single white flowers suddenly begin to pop open creating a blizzard of deliciously scented clusters that cover a straggly shrub from top to bottom.


P. lewisii growing in the upland forest restoration site out in UBNA.

P. lewisii growing in the upland forest restoration site out in UBNA.

Found in open forests in low-mid elevations, Philadelphus lewisii is highly adaptable to the garden where it becomes a large shrub and requires only well-drained soil, moderate moisture, and full sun to part shade. It seems to tolerate competition from other plants very well, but requires some pruning to keep its size in check and to remove dead or non-productive  wood.

A established specimen in full bloom along the entrance into UBNA

A established specimen in full bloom along the entrance into UBNA

Philadelphus lewisii portrait 2


Common Name:  Lewis’s Mock Orange
Location: Union Bay Natural Area
Origin: Pacific NW Native
Height and Spread: 6-7′ tall and about 5-7′ wide
Bloom/Fruit Time: Late May – Early July

May 2014 Plant Profile: Paeonia suffruticosa (Rockii Group)

May 6th, 2014 by Soest Gardener, Riz Reyes

Paeonia rockii type Joseph Rock’s Peony has been prized by gardeners and avid collectors for decades. Botanist and  plant explorer Joseph Rock earned the honor of having this exquisite flower named after him.

Peonies are divided into two basic types; the bush or herbaceous peony and the so-called tree peony. With similar flowers, the main difference between the two are their bloom times and their growth habit. Herbaceous peonies die back down to the ground each winter and bloom later in the season (May-June) whereas the tree peony, which isn’t really a tree, is more like a shrub with stems and branches that do not die back to the ground and flower mostly in May. Paeonia rockii is a tree peony.

Tree peonies are long-lived shrubs with exquisite flowers, but they take careful placement and a lot of patience until they’re well established.

They are best planted in the autumn so they are able to start forming new roots over the winter and it’s critical that they are planted in a location with full/part sun, well drained soil, good air circulation, and protected from strong winds that could damage the brittle branches. They can take several years to get established to consistently bloom each year and they also resent being transplanted.

Paeonia rockii



Common Name:  Joseph Rock’s Tree Peony
Location: Pacific Connections – China Entry
Origin: Gansu, China
Height and Spread: 6-8′ tall and about 5-7′ wide
Bloom/Fruit Time: Early-Mid May


A few selections of P. rockii can also be found growing at the Seattle Chinese Garden.

April 2014 Plant Profile: Convallaria majalis ‘Striatum’

April 3rd, 2014 by Soest Gardener, Riz Reyes

Spring flowers are in abundance in April, but very few possess the charm and delightful scent of the infamous lily-of-the-valley. Known to be a thug in the garden once established, a variegated selection appeared that seemed to not grow as quickly. Still quick to spread in rich, moist soil and capable of competing with neighboring plants, the thin yellow striping along the leaf is quite unusual and can light up shady areas both before, during and after bloom.  The only caveat to growing this plant is its tendency to revert back to all-green foliage. Once this is encountered, simply yank out the green reversions to maintain excellent foliage color.


Common Name:  Variegated Lily-of-the-Valley
Location: Soest Garden Bed 7
Origin: Garden Origin
Height and Spread: 6-8″ tall and can spread forming patches in the garden.
Bloom/Fruit Time: April-May