Kubota Garden

Kubota Garden is a stunning 20-acre garden composed of hills and valleys, featuring streams, waterfalls, ponds, rock outcropping, and an exceptionally rich and mature collection of plant material. This unique urban refuge displays over 60 years of vision, effort, and commitment by the Kubota family.  Master landscaper Fujitaro Kubota was a horticultural pioneer when he began merging Japanese design techniques with North American materials.

In 1927 Fujitaro bought five acres of logged-off swamp land in the Rainier Beach neighborhood of Seattle and began his garden. Fujitaro was a man with a dream, entirely self-taught as a gardener, he wanted to display the beauty of the Northwest in a Japanese manner and was soon designing and installing gardens throughout the Seattle area. The garden on the Seattle University campus and the Japanese Garden at the Bloedel Reserve on Bainbridge Island are public examples of his work.

As Fujitaro's landscaping business prospered, his Rainier Beach Garden grew to 20 acres in size. It was the family home, the business office, a design and display area and a nursery to grow plants. In the 1930's, a natural stream was enclosed in a pool and surrounded with maple, pine, iris, and stone. In the forties during World War II, the garden was abandoned for four years while the Kubota family suffered internment at Camp Minidoka in Idaho. Fujitaro and his sons, Tak and Tom, restarted the landscape business after the war and began extensive plantings of nursery stock. Many of these nursery areas are still in use today.

In 1972 the Japanese Government awarded Fujitaro Kubota with a rare honor, the Fifth Class Order of the Sacred Treasure, “for his achievements in his adopted country, for introducing and building respect for Japanese Gardening.”

Fujitaro died in 1973 at age 94. He had always hoped that the garden would one day be open to the public, both to enhance the quality of life in Seattle and to increase American understanding and appreciation of Japanese culture. In 1981 the American Japanese Garden, created by Fujitaro, was declared to be an Historical Landmark of the City of Seattle.

Rhododendron calendulaceum

Have you ever taken the Blue Ridge Highway and watched a full scene of flaming color.  It takes your breath away.  You are seeing Rhododendron calendulaceum in its glory.  It is one of the most spectacular native shrubs of the Appalachian Mountains.  E.H. Wilson, the notable British plant collector and explorer, wrote, "..."It must be considered one of the most gorgeous of American shrubs."  Why?

  • its unopened buds give a resemblance to candle flames,
  • its flowers are very showy and are larger than most other natives,
  • the color is termed fiery, was said to have alarmed early explorers who, upon viewing a whole hillside in bloom, thought they were ablaze,
  • colors range from yellow, yellow-orange, orange-red, and red, usually with an orange blotch on the upper lobe,
  • leaves are 1 to 3-in. long, medium to dark green above, with short hairs below, both leaves and branches often appear in whorls.

A little background surrounding this gem: calendulaceum means like a "calendula," a genus of flowering plants with similar flower color.  It is one of 16 species in Rhododendron subgenus Pentanthera, section Pentanthera, referred to as the deciduous azaleas. it's commonly called the "Flame Azalea".

It was first identified in 1795 by Andre Michaux, a French botanist, in the Southeastern U.S. and since has played an important role in the early development of the Ghent Hybrids, which began with its cross with R. periclymenoides.

This gorgeous gem forms an upright, spreading shrub or small tree, which can grow from 4- to 15-ft. tall in the wild. but usually is much shorter in cultivation.  Typical bloom time is May through June at which time you will find entire hillsides brilliantly colored.  Its native habitat includes open, dry sites in woods, on cliffs and hillsides, and on bald open area on mountaintops from 600 to 5,000 ft.  It is hardy to Zone 5 (-25°F or -30°C).

R. calendulaceum has close relatives! With the closest one being R. cumberlandense, a smaller plant with a paler flower.  The scarcity of natural hybrids may be due to it being a tetraploid. whereas other azaleas in its range are diploid.  Because of this genetic incompatibility, its hybrids are often sterile.

R. calendulaceum is difficult to propagate from cuttings, but it is very easy to grow from seed.

pH - Why is it important for rhododendrons?

What is pH? How do I obtain a proper pH for my rhododendrons?

pH refers to the acidity of a material. Technically, it is a measurement of the hydrogen ion content. The pH scale ranges from 0 to 14, pHs of 0 to 7 are acidic, pHs of 7 to 14 are referred to as being basic or alkaline. A pH of 7 means the material is neutral. For rhododendrons the preferred pH should be between 5 and 6.5.

It is difficult for a layperson to determine the pH of the potting medium they use. There are pH meters on the market, but the ones that cost less than $100 are practically worthless. However, it is fairly easy to get your growing medium pH in the desired range. Fir or hemlock bark is almost always in an acceptable range and, therefore, an ideal growing medium to use. It is best if the bark has decayed for six months prior to use.

The reason pH is important for plants has to do with the intake of minerals and nutrients. If the pH is too low, rhododendrons have difficulty taking in the nitrogen and phosphorous they need for growth. If the planting medium of soil is too alkaline, i.e. the pH is too high, it usually causes iron and/or manganese deficiencies.

In summary, pH is important for growing healthy rhododendrons. Generally, it is advisable to use fir or hemlock bark in pots and bark or pine needle mulch as an additive for plants grown in the ground.

Iron-Clad Rhododendrons

R. catawbiense was collected in the wild in 1803 in the Eastern U.S. and was introduced to Britain in 1809. When hybridized with other rhododendrons it introduced cold and heat hardiness into rhododendron hybrids. The first group of rhododendrons to become popular in gardens was the hybrids called the "iron-clads." There were a group of early British hybrids involving crosses of R. caucasicum, R. catawbiense, R. ponticum and R. maximum that survived the coldest winters at Arnold Arboretum in Boston. In 1917, Ernest Henry Wilson (1876-1930) published a list of what he termed the "Iron Clad" rhododendrons that for many years were successfully growing in the Arnold Arboretum.

 Wilson's Dozen Iron-Clad Rhododendrons

 1. Album Elegans, pale purplish pink hybrid or selection.
 2. Album Grandiflorum, pinkish white hybrid or selection.
 3. Atrosanguineum, bright red with purple markings hybrid.
 4. Catawbiense Album, pinkish white hybrid or selection.
 5. Charles Dickens, crimson red with purplish markings hybrid.
 6. Everestianum, purplish-pink with green markings hybrid.
 7. Henrietta Sargent, a deep pink hybrid.
 8. Lady Armstrong, deep purplish pink, pale center hybrid.
 9. Mrs. Charles S. Sargent, rose pink hybrid.
10. Purpureum Elegans, pinkish purple hybrid.
11. Purpureum Grandiflorum, violet with green flecks hybrid.
12. Roseum Elegans, lavender pink with green markings hybrid.

Rhododendron decorum

Rhododendron decorum was first described by Adrien Rene Franchet in 1886 from a plant collected in Moupin, western Sichuan. It was introduced to cultivation in 1887 by Pere Jean Marie Delavay. In the wild it can be found throughout west and southwest Sichuan, southeast Tibet, northwest Yunnan and northeast upper Burma. It grows in pine, spruce, and open deciduous forests, and on grassy mountains and rocky scrub. It is found at elevations of 6000 to 15,000 feet.

The foliage is variable but typically shaped oblanceolate to elliptic, up to 7" long, smooth green on both surfaces, with rounded ends. The funnel-campanulate flowers are white to pink to pale lavender, variously marked and quite fragrant. Held in an open-top truss with 7-12 flowers.

There are two subspecies, ssp. decorum and ssp. diaprepes, with the former having smaller leaves and corolla and fewer stamens.

R. decorum is quite variable in hardiness. Typical cold hardiness is 0°F (-18°C).

Plants in cultivation are easily grown and generally bloom at an early age. With a May/June bloom time and a pleasant fragrance, R. decorum is worth growing in your gardens.

R, decorum has found considerable use with hybridizers and many fine hybrids have been produced, including R. 'Caroline', 'Lackamas Spice', 'Newcomb's Sweetheart', 'Apricot Sherbet', and 'September Song'.

Rhododendrons In Bloom Today

Here in the Pacific Northwest, we've had a cold, wet and windy spring, so plants are late blooming this year. However, I've finally got a bit of good colour showing now in early April.

R. 'California Gold' is a R. maddenii hybrid, and tender for us so I keep this beauty in a container and bring it in whenever frost is predicted. It's a bit of a nuisance to do, but whenever I see it blooming, I'm glad I took the trouble. The large flowers are soft yellow with brown anthers that show up nicely against the petals. The outer edges of the petals are just a bit frilly, so really nice and, they have the added bonus of excellent fragrance. When in bloom, 'California Gold' perfumes the sunroom and adjacent dining room. One other attractive attribute is the dark red shedding bark.

R. 'California Gold'
R. 'California Gold'

R. 'Shamrock' is another pale yellow flowered hybrid in bloom today. Among my acquaintances, I find some people aren't impressed with 'Shamrock'. They think it's too pale with a bit too much green in the flower colour to stand out well. Well, that's just crazy talk! I think this is a sweet, tough little plant and I value it for its early blooms. It is often out in mid-March although this year it's a couple of weeks later. The parents are a dwarf form of R. keiskei and R. hanceanum nanum and 'Shamrock' has inherited their small stature. And, for those who wish it had showier flowers, put it next to something blue like 'Muscari' as the colour contrast is very attractive.

R. 'Shamrock'
R. 'Shamrock'

My third "bloomer of the day" is lovely R. dendrocharis. This species rhododendron has flat-faced, open flowers of bright pink. The leaves are tiny and very dark green. In the wild, R. dendrocharis usually grows as an epiphyte, so it needs excellent drainage. Other than that, I've found it easy to grow. I keep it where it gets dappled shade and protection from the noonday sun during the summer.

R. dendrocharis
R. dendrocharis