Your browser does not support script.
US National Arboretum


Azalea Blossom Watch 2006

Current Conditions

March 29 | April 4 | April 12 | April 19 | April 26 | May 3 | May 11 | May 17 | May 25

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 2006, the peak azalea bloom should be between April 22-30. However, the first azaleas begin to bloom in early April with the daffodils and the forsythia, and still others are Images of azalea blossoms blooming as late as July with the daylilies.

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.


image of Daffodil blooms

To the untrained eye, it might still seem like winter outside. At the US National Arboretum, however, the staff are busily mulching, pruning and planting. The first signs of spring are showing up all over our 446 acres. Daffodils, cherries and magnolias are in color with their pastel blooms. For the next eight weeks, Barbara Bullock, curator of Azaleas and Rhododendrons will attempt to describe the azaleas as spring unfolds in the Azalea Collections.

  image of Rhododendron mucronulatum azalea blossoms


March 29

The first of the Glenn Dale azaleas has started to bloom today, March 29, 2006. With warm temperatures and sunny skies ahead, more should be open by the weekend.

To find these blooms take the upper Mt. Hamilton Trail from the Morrison Garden to trail marker #8, and look down. There you will find a mass of pink azalea flowers opening up toward the southern sun.

Many people have asked me if the dry spring we've been having will affect the bloom, and the answer is no. Not yet. Our temperatures have remained cool, and the soil moisture just under the surface is still reasonably good. If you planted anything earlier this spring, or late last fall, it would be good idea to give the new plants a good soaking, but everything else should be fine.

(photo: Rhododendron mucronulatum)


April 4th

image of Weston hybrid 'Peach Blend'

The Arboretum recorded a much welcomed 1/2 inch of rain last night; with that and the wonderful cool but not freezing nights, the peak azalea bloom should be right on schedule - between April 22-30, the azaleas will be spectacular.

Currently the first of the evergreen azaleas called Kurume hybrids have started to bloom. Located on the upper Mt. Hamilton Trail above the massed Glenn Dales facing south, these have smaller flowers, less than an inch in diameter, in many colors such as magenta, red, apricot, white, pink and lavender. Another planting of Kurumes exists on the east side of the garden but will not bloom for another week due to the sun exposure.

Several different Japanese species are in full bloom right now. The first, Rhododendron kaempferi, (Kaempfer's Torch Azalea) is reddish orange. This upright growing semi-deciduous species was used in the hybridization of the Glenn Dales to add hardiness as well as the early blooming characteristic. Some Glenn Dales using R. kaempferi are 'Aladdin', 'Morgana', and 'Bagatelle', all of which will be blooming in the next two weeks.

Rhododendron reticulatum (Rose Azalea) is a deep pink deciduous species and is seen from the Lee Azalea Garden. By this weekend, expect to see Rhododendron keiskei, another Japanese species which has creamy yellow flowers and small evergreen leaves.

(photo: Weston hybrid 'Peach Blend')


April 12th image of 'Allure'

The light freeze that sprinkled over the metropolitan area this past Monday morning (April 10) seems to have skipped the National Arboretum. Our records indicate that the temperature got down to 37 degrees Fahrenheit which means that the magnolias, cherries, daffodils and early azaleas that were in bloom the day before will continue to bloom their normal duration.

Today, many Glenn Dales are showing color. 'Dayspring', 'Allure', and 'Festive' are fully open and can be seen in the Morrison Garden which features the Glenn Dale hybrids. The projected peak bloom period is expected to be between April 21-30. The Glenn Dale azalea hillside has color throughout its approximately seven acres.

Some interesting Rhododendrons in bloom today include Rhododendron macrosepalum var. linearifolium, or, the Spider Azalea. One of the more unique azaleas, this one often suffers from bud blast due to freezing temperatures in late winter, and doesn't bloom well every year. But not so this year. Another early lavender azalea is the Korean Azalea, Rhododendron yedoense var. poukhanense, a very popular lavender that can be seen all over the Washington D.C. area as well as above the grove of Dawn Redwoods (Metasequoia glyptostroboides) on Azalea Road. This species was used extensively in the development of the Gable hybrid azaleas such as 'Corsage' and 'Cameroon.'

(photo: Glenn Dale 'Allure')


April 19th image of Orange florida flame azalea, Rhododendron austrinum

A common question this time of year is "When will the peak azalea bloom occur?" It's often hard to pick a specific date as conditions change from year to year that may affect when the azaleas bloom. This year is a perfect example. The Collection is actually a week earlier than last year at this same time. The combination of the early azaleas, the dogwoods, and the beginning of the mid-season azaleas is spectacular.

If forced to pick a peak date, it's looking like next Tuesday, April 25, may be the day, but you will not be disappointed if you make a visit any time between now and the end of April. This week, if you walk into the Azalea Collections, you will see the Kurume and Glenn Dale hybrids and thousands of other evergreen azaleas in bloom. A number of deciduous azaleas are also blooming, including the orange-flowered native Florida Flame azalea and the white-flowered native called the coast azalea. Traveling along the Henry Mitchell Walk, you'll see the yellow-flowered Pontic Azalea native to the Caucasus Mountains.

Plan a visit to the Arboretum's Azalea Collections soon to enjoy one of Washington, D.C.'s most fabulous botanical displays!

(photo: Orange florida flame azalea, Rhododendron austrinum)


April 26th image of azaleas in bloom on a hillside at the Arboretum

The azaleas are at their peak right now, and will continue to be at peak through the weekend. The easiest time to visit the Azalea Collection is during the week when it is less crowded but don't let that stop you from taking a stroll this weekend, (after going to the FONA Plant Sale, of course). There will be lots of azaleas for sale including many natives which can be a delightful addition to your garden.

Seen among the thousands of Glenn Dales, Kurumes and Kiusianum hybrids are the orange blossoms of the deciduous Rhododendron austrinum (Florida Flame Azalea) and the fragrant white flowers of Rhododendron atlanticum (Coast Azalea). The Morrison Garden contains over 200 of the Glenn Dale hybrids introduced by the National Arboretum in the 1940's and 50's. The Robin Hill hybrids are beginning to bloom and can be seen along the Henry Mitchell Cultivar Walk located halfway between the Lee and the Morrison Gardens. Trail guides to the Azalea Collection are available at the front desk of the Administration Building lobby.

(photo: This hillside is a burst of color as thousands of azaleas at the Arboretum reach their peak.)


May 3rd image of azaleas in bloom on a hillside at the Arboretum

For some reason, the comments I'm getting the most when I'm working in the Azalea Collections this week are whether I think we are at peak or past peak. The Kurume Azaleas, earliest of the evergreen hybrids, have pretty much finished with their bloom cycle but thousands of mid-season azaleas are opening daily.

Today and this weekend, the Glenn Dale hybrids are at their best. Considered to be among the most splendid of evergreen hybrids, the Glenn Dales were developed in Glenn Dale, Maryland from 1925-1952 and introduced by the National Arboretum in 1952. Over 200 specimens are featured in the Morrison Garden, named for the National Arboretum's first Director, Benjamin Y. Morrison who was responsible for their introduction and did all the breeding work.

Located to the south of the Morrison Garden is the Glenn Dale Azalea Hillside, which is planted with over eight acres of Glenn Dales. To the east is another 15 acres of evergreen hybrid group azaleas dotted with deciduous azaleas and large-leaf rhododendron hybrids. Arranged by hybrid group and interpreted as the Henry Mitchell Cultivar Walk, one can view thousands of cultivars, learn their names and see how they compare with others.

The cool spring weather we've been having has been favorable for all azaleas. So are we at peak or past peak? Why don't you come by and take a peek?

(photo: The red azalea collection is located beside the steps leading up to the Lee Garden.)


May 11th Rhododendron (HTS Group) 'White Selection # 5'

The mid-season blooming azaleas are in full swing up on Mt. Hamilton this week. The Ben Morrison Azalea Garden is at peak bloom as well. If the rains come as predicted, the gardens will still provide a splendid place to walk - in fact I would say it is one of the best times for great lighting for photographs.

Some wonderful mid-season bloomers can be seen such as the creamy Glenn Dale 'Treasure' (known for the mauve blotch and the large white flower). One of the lesser known National Arboretum introductions named Belgian-Glenn Dale 'Pink Ice' was introduced by Dr. John Creech, the National Arboretum's third director, and can be seen along the upper path of the cultivar group collections.

There are many Harris hybrids, but there is no other dark red like Harris's 'Midnight Flare' located along the steps leading up toward the Lee Garden. Rhododendron HTS selection 'White' is a beautiful starry azalea introduced by the National Arboretum's second director, Dr. Henry Skinner, and can be seen along the middle cultivar path. The cultivar groupings of the Azalea Collections are located between the Morrison and Lee Gardens and are described by the Henry Mitchell trail guide and walk. 'Ho Oden' is an early Satsuki azalea with very rounded flowers that make for a beautiful focal point in the garden.

(photo: Rhododendron (HTS Group) 'White Selection # 5' is a beautiful starry azalea and can be seen along the middle cultivar path.)


May 17th Mrs. Emil Hager

The fragrance of honeysuckle is drifting through the air almost two weeks earlier than usual, and that is the same for the later blooming azaleas. This week's visit to the Azalea Collection still has a lot of color to see, but for the most part, one is struck by the lush greenness of it all. The Morrison Garden is stately still with blooming climbing hydrangea softening the edges of the garden and the yellow variegated dogwood 'First Lady' stands out against the dark-red 100-year-old brick.

Now is the time for the larger flowered and double flowered varieties to begin their blooming. The North Tisbury 'Eiko San' is the first of the North Tisbury hybrids to bloom with salmony-red double flowers. The doubled-flowered form of the Japanese Riverbank Azalea, Rhododendron indicum 'Balsaminiflorum' and the Satsuki hybrid 'Beni Kirishima' are several doubles one sees today. The Robin Hill hybrids 'Whitehead,' 'Corry,' 'Mrs. Villars,' 'Mrs. Emil Hager,' and 'Sara Holden,' as well as many others are in full bloom right now. Flower diameters reach 3 1/2 inches or more across. Shrubs with sporting branches of a different color than the dominant one are visible in the Robin Hills. This is due in part to their Satsuki parentage used in their breeding. The Satsuki hybrid azaleas are starting to bloom, and can be found in and around the Frederic P. Lee Azalea Garden.

The season for blooming azaleas is still on. We are now looking at the late season cultivars. Come and see.

(photo: 'Mrs. Emil Hager' looks lovely in an alluring shade of pink.)


May 25th R. Weston 'Framingham'

The azalea collection is settling back for the summer, but there are still many late blooming azaleas, both deciduous and evergreen, to come. The North Tisbury and Satsuki hybrids always bloom late, and come in many colors from red to purple to pink to white. There are still many Robin Hill azalea cultivars in bloom and there is even one late blooming Glenn Dale 'Pink Star,' which grows to five feet tall but after 30 years, has a 25-foot spread on one plant.

Several deciduous azaleas make their appearance at this time, along with the mountain laurels and large rhododendrons. The Flame Azalea, (Rhododendron calendulaceum) blooms orange and the Cumberland Azalea (Rhododendron cumberlandense) and the Smooth Azalea, (Rhododendron arborescens) are all coming into bloom at this time. They represent some underutilized plants for the landscape, and are all native to eastern North America. Finally another native, the Plumleaf Azalea, (Rhododendron prunifolium) will not open its brilliant red blossoms until late June or early July when one can also see the Weston group of "summer flowering" selections of our natives.

This will be my final installment of the Azalea Blossom Watch for the 2006 season. It has been cool spring season this year, but overall not much rain has fallen. Be sure to check all your newly planted plants regularly especially as the temperatures start to get over 80 degrees Farenheit and water as needed. A good soaking once per week is much better for establishing new plant material than a light misting every day. See you in the garden!

(photo: R. Weston 'Framingham')

 Back to the Arboretum Home Page
Arboretum Information || Events & Education || Gardens & Horticulture || Research Activities
Support the Arboretum || New Plant Introductions || USDA Plant Hardiness Zone Map || Comments
Search Our Site

Last Updated   July 12, 2006 4:24 PM