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US National Arboretum


Azalea Blossom Watch 2007

Current Conditions

April 4 | April 11 | April 18 | April 25 | May 2 | May 9 | May 16 | May 23

Experience the National Arboretum's treasured Azalea Collections.
Experience the explosion of color when thousands of azaleas at the National Arboretum light up the forest with their subtle shades and colors. In 2007, the peak azalea bloom should be between April 23-30. However, the first azaleas begin to bloom in early April with the daffodils and the forsythia, and still others are blooming as late as July with the daylilies.

Images of azalea blossoms

The best time to schedule your visit is on a week day, but if weekends are your only option, a stroll through the garden before noon or during a light rain offers an enviable second choice. A drive around Azalea Road can be exhilarating because of the views of the Collection, but if you can afford the time and take a walk, it is worthwhile. Park in the nearby M Street parking area, and walk to the Morrison Garden. Pick up a brochure there, and begin your journey into the world of azaleas.

Visit our Azalea Photo Gallery where you will find over 200 images of the flowers of more than 100 of the Glenn Dale azalea varieties.

In the meantime, check back here each week as we update you on the current conditions in this year's Azalea Blossom Watch. [To see other images, "mouse-over" the highlighted text for a small pop-up image].


April 4th

image of Weston hybrid 'Peach Blend'

Spring is upon us once again. The National Arboretum is teaming with flowering cherries, magnolias and redbud. The short warm spells tricked a few flowers into blooming earlier than their natural bloom cycle, but all in all, the spring in Washington D.C. is normal. The average peak bloom for the azaleas in our azalea collection is scheduled, as in previous years, to be between April 23 and April 30.

Today, several early species of Rhododendron are in bloom: Rhododendron mucronulatum, Rhododendron dauricum, and Rhododendron keiskei (a pale yellow flowered "small leaved" rhododendron). All three are known collectively to botanists as lepidote rhododendrons. These species were in turn used to breed several early blooming cultivars. The Weston Group of early-blooming rhododendrons used the lepidote species Rhododendron mucronulatum to create cultivars as 'Peach Blend' and 'PJM' and 'Olga Mezitt' which are now coming into bloom.

The earliest of the Glenn Dales and Gables will likely have Rhododendron kaempferi in their lineage. The azalea species in bloom today is Rhododendron kaempferi (Kaempfer’s Torch Azalea, from Japan). The staminate form (the petals look like stamens) of this species is called 'Kinshibe' and is in bloom this week.


April 11th

image of 'Allure'

The number one question on everyone's mind is "Will this recent five day stretch of freezing temperatures affect the seasonal display of azaleas at the National Arboretum?" The short answer is "no". Our night time temperatures the last three nights only got down to 31 degrees F., and were above freezing last week. If this trend keeps up, however, the peak bloom period may be delayed up to a week or more. We will keep you informed on this link with our weekly updates. Daffodils and dogwoods are coming into bloom throughout the Arboretum as spring marches forward.

Today, Rhododendron reticulatum, a lovely rose-lavender species azalea from Japan is in bloom in the Lee Azalea Garden. Many of the Weston hybrid group of early blooming rhododendrons are blooming. These include the cultivars 'PJM', 'Vallya', 'Landmark' and 'Hudson Bay'. Rhododendron keiskei is still blooming with its pale yellow flowers.

Of the evergreen azaleas, there are buds beginning to show color all over Mt. Hamilton as one drives around Azalea Road to see hillside of Glenn Dale azaleas. Inside the Morrison Azalea Garden, the first of the Glenn Dales hybrids are coming into bloom. You can see 'Dayspring', 'Dream', 'Allure', 'Minuet', and 'Sebastian' nearing full bloom. The smaller-flowered Kurume hybrids are also beginning to come into bloom. The Kurume hybrids are located along the Henry Mitchell cultivar walk, a main route through the azalea collection which describes the various hybrid groups featured here.


April 18th image of Korean Azalea, Rhododendron yedoense var. poukhanense

Thousands of azaleas are slowly beginning to show their color for the spring display. The cooler temperatures we have been experiencing this year have indeed slowed them down so we expect the peak bloom to be closer to the end of April into early May, this spring.

Today, the lavender flowers of Rhododendron yedoense var. poukhanense, the Korean Azalea and R. mucronatum var. ripense, the Riverbank Azalea, are in full bloom. Both azalea species were often used to breed cold-tolerance into many of the azaleas we see in our yards today. Gable’s 'Corsage' is a very popular lavender azalea widely available and is in bloom today.

We are also seeing the blooms of the Weston hybrid rhododendrons, 'Landmark' and 'Vallya'. Both are lepidote rhododendrons which have small waxy leaves that persist through most of the winter. (In some winters, when it is cold enough, they will have beautiful red or orange fall color.) There are more varieties with new colors opening every day.


April 25th image of azaleas in bloom on a hillside at the Arboretum

The warm temperatures in the low 80's have succeeded in speeding up the process of opening the azaleas. This weekend will be the beginning of the peak season for the azaleas this year. Each day more azalea hybrids will open demonstrating the vast array of bloom times available in azaleas. The peak will continue on through the week as well, when plenty of parking and open trails are more available. The Arboretum has made arrangements for ample parking this weekend, due to the scheduling of our annual plant sale, held by FONA (Friends of the National Arboretum) this weekend at our New York Avenue parking lot. There will be shuttles for parking; tents for shade; food vendors; and many Arboretum staff available to talk to – the plant sale which is mainly on Saturday, April 28th is an excellent reason to come visit the National Arboretum this weekend.

The Morrison Garden is a formal garden, which contains the collection of azaleas developed by Ben Morrison, demonstrates how bloom time is staggered within the Glenn Dale hybrid group of azaleas. This is the result of using many different species and hybrids in the breeding of the Glenn Dales which were introduced by the National Arboretum in the 1940's and 50's.

Featured along the Henry Mitchell cultivar walk, are several other hybrid groups of azaleas. Featured this way, the theme of the hybridizer(s) can be seen. The Kurume hybrid azaleas are in full bloom this week. Known for their smaller flowers and more branched growth habits, the early-blooming hybrids from Kurume, Japan were among the first of the evergreen azaleas that became widely available to the public for planting their gardens in the early 20th century.


May 2nd image of azaleas in bloom on a hillside at the Arboretum

The azalea collection is in peak bloom right now and will continue for another week or more. Do not let parking worries deter you from visiting over the weekend. The parking lot at M Street is a short walk from the Morrison Garden and there are picnic tables available for spontaneous gatherings. If you are really up for a nice walk, the new Flowering Tree Walk path will connect you from the north end of the Azalea Collection to the Herb Garden/Bonsai/Koi pool at the Administration Building over to the Capitol Columns and Fern Valley.

Along with thousands of Glenn Dale azalea, (the popular hybrids introduced by the National Arboretum) are Kurume azaleas, deciduous azaleas, (many of which are native to North America) and thousands of others.

The Azalea Hillside is a burst of color as thousands of azaleas at the Arboretum reach their peak.

The Henry Mitchell Cultivar Walk will direct you past labeled collections of cultivar groupings of azaleas. Here are a few examples: a view of Kurume azaleas; a view of salmon azaleas; and, a view of red azaleas.


May 9th Rhododendron (HTS Group) 'White Selection # 5'

The cool temperatures are fantastic for the azalea bloom this year. The coming week promises to be as beautiful as the previous two. The Kurume azaleas are finished blooming for the year, but now is the prime time to see what the Glenn Dale azaleas are all about. These hybrids were bred to have larger flowers and to extend the season of bloom for spring-flowering azaleas. Some Glenn Dale azaleas such as 'Nubian', 'Roundelay' and 'Quakeress' will reach heights of over six feet, and have flowers that are three inches in diameter. Over 200 specimens of Glenn Dale azaleas are featured in and around the Morrison Garden named in honor of the breeder of the Glenn Dales, and the Arboretum’s first director.

The Robin Hill azaleas are starting to come out as well. Bred for shorter stature, and beautiful blossoms, the Robin Hills are located in the Loop Area Collections along the Henry Mitchell Cultivar Walk. Over 1,975 accessions of labeled plants are located along this walk, designed to teach people about the richness and variety of hybrid azaleas.

Located to the south of the Morrison Garden is eight acres of over ten thousand Glenn Dales planted between 1946 and 1947. Seeing it in person is a breathtaking experience. Come take a walk through azalea-filled woodlands still in their peak bloom.


May 16th Azalea hillside blooming

The mid season azaleas are in full bloom right now. These are represented in a large part by the Glenn Dales and Robin Hill hybrid groups of azaleas, but there are many others as well. The Morrison Garden is at its peak right now. In the Lee Garden, some early Satsuki azalea hybrids are also in bloom this week. It is possible that by this weekend, many more delightful unusual Satsuki hybrids will be coming into bloom.

Some wonderful mid-season bloomers such as 'Rakuyo' and 'George Lindley Taber' are showing off large (3 ½”) coral blossoms. One of our favorites, 'Ben Morrison' named for the Arboretum’s first director, is in full bloom with large coral-red flowers with distinctive white feathered margins. This is the time for larger flowers, unusual forms of flowers and multiple colored flowers. The Belgian-Glenn Dale 'Pink Ice' is in bloom with pale lavender pink flowers and unusual petalloid stamens in the centers of each flower. The Belgian-Glenn Dale hybrids are a result of a 1947 cross between the much hardier Glenn Dale 'Treasure' with a double pink florist azalea and was introduced by John Creech and B Y. Morrison.


May 23rd image of Glenn Dale 'Pink Star' azalea flowers

Some azaleas are meant to bloom late. This is the case for the beautiful Glenn Dale 'Pink Star' seen along the steps in the north side of the Azalea Collection. Covered with large reddish coral blossoms (see image at right), the overarching branches of this five foot tall azalea have found the ground again and set new roots (called "layering"), which in turn grew to five feet causing the original plant to spread to over 15 feet in width, making for an incredible late blooming display. Other late blooming Glenn Dales include 'Elizabeth', 'Picador' and 'Eros'.

Our Satsuki, North Tisbury, and Robin Hill hybrid grouping of azaleas show off another 100 or so cultivars which will always bloom later in May and into June. The large leaf rhododendrons (elepidote) are in full splendor right now, as are our new collection on cultivated mountain laurel (Kalmia latifolia) introduced by Richard Jaynes.

This is our final installment of the Azalea Blossom Watch for 2007. We wish to encourage you to venture into the Azalea Collections throughout the summer to see other later blooming azaleas, such as the native Plumleaf azalea (Rhododendron prunifolium), and to enjoy the quiet woodsy solitude of the collection during slower times. You might even see some unusual wildlife.

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Last Updated   May 24, 2007 10:37 AM

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