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US National Arboretum


Azalea Blossom Watch 2016
Current Conditions

April 1 | April 12 | April 25

Experience the National Arboretum's treasured Azalea Collections

Spring is upon us once again, and the National Arboretum is rich with bloom from the spring ephemerals to the daffodils, magnolias and cherries planted throughout the grounds. This column which begins today and will change each week for the next eight weeks will focus specifically on our Azalea Collections and the status of bloom.

Experience the explosion of color when thousands of azaleas at the National Arboretum light up the forest with their subtle shades and colors.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. We hope that this Azalea Blossom Watch will give you insight into the range and diversity of the Rhododendron species and cultivars growing at the National Arboretum, as well as help you with planning your visit.

Images of azalea blossoms

The best time to schedule your visit is on a weekday, 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 to take a walk, it is worthwhile. Pick up a brochure at one of the three major entrances to the collections or at the Visitor Information center and begin your journey into the world of azaleas.

Learn more about the Azalea Collection here. For more in-depth information on growing and caring for rhododendrons or azaleas, check out the FAQ pages here. 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.

April 1

R. Weston Grp. 'April Snow'Greetings to our friends and guests! Check here for bi-weekly updates on the status of the bloom season in the Azalea Collection. This week along with the mid-season magnolias, cherries, and daffodils, the first Glenn Dale azaleas are in bloom.

A pair of bald eagles are raising two new eaglets in their nest in a tulip poplar in the azalea collection. A portion of the Glenn Dale Hillside is closed to visitors to ensure that the eagles won't be disturbed in any way. You can see what they are doing by visiting the Eagle Cam page.

The Glenn Dale azaleas started to bloom on March 15th, about two weeks ahead of normal. In the Morrison Garden the following Glenn Dales are blooming: 'Dayspring', 'Festive' and 'Dream'. Cooler temperatures will slow down the opening of the flowers, but will not hurt the overall display. Several of the Weston hybrids such as 'Olga', 'PJM', and 'Landmark' are starting to bloom. These cultivars have fantastic winter foliage, and will bloom every year at the same time as forsythia. Early Rhododendron species that are in full bloom in the collection are: R. mucronulatum (lavender), R. keiskei (pale yellow) and R. reticulatum (pinkish-lavender). R. Weston Grp. 'Weston's Starburst'

The different varieties of azaleas will bloom for the next four to six week with the peak around the week of April 20. If the weather stays cool, the early season blooms will persist longer and remain when the mid-season azaleas open. Every year is a little different. The collection consists of thousands of azaleas, and each one blooms an average of two weeks.

This season's highlights include the addition of 100 Aromi hybrid deciduous azaleas, sure to grab your attention when their orange and yellow blossoms contrast with the purples, salmon, and pinks of nearby azaleas. See you in the garden!


April 12

There are many azaleas opening this week. The Kurume azaleas that were brought to the United Stated from Japan in the early 20th century and are found in gardens throughout the country are in bloom. The entire hybrid group is known to be hardy. A few opened flowers did get damaged during our recent freeze in early April. The image to the right shows frost damage on some of the flowers, while other flowers were untouched.

The early Weston rhododendrons are still in bloom. 'PJM', 'Olga' and 'Landmark' are the most popular of this group. They are known as lepidote rhododendrons and are characterized by having smaller leaves and the presence of scales usually on the undersides of their leaves. Rhododendron minus, a native to the northeast is a lepidote rhododendron.

Rhododendron 'Montchanin' is another unusual early blooming cultivar with small white flowers and is part of a group of Rhododendrons hybridized by G. Guy Nearing using Rhododendron keiskei crossed with R. pubescens. Nearing is the inventor of the Nearing cold frame, widely used to propagate and raise plants early in the spring season without the use of electricity ( They should be in bloom this weekend.

Other early azaleas in bloom are R. yedoense var. poukhanense and R. kaempferi. These two species have been widely used as parents in breeding hardiness in azaleas that are seen in landscapes throughout the region. We have several unique forms of these. R. 'Kinshibe' has an unusual spider-like flower form that resembles a mimosa flower. In the Morrison Garden, you will also find 'Allure', 'Festive', 'Dream', and many other early Glenn Dales coming into bloom this week. Peak azalea bloom will begin around April 20th, and last into early May.

See you in the garden!


April 25 - May 10

This weekend is the peak for the Azalea Collection. The earliest of the evergreen azaleas have just about finished blooming, and now is the time for the mid-season blooming azaleas. This year was early for many flowering plants including azaleas. Mid-season azaleas normally start to bloom by April 30th.

The Glenn Dales azaleas that are featured in and around the Morrison Garden (see image at left) are the product of the hybridization work of the arboretum's first director, Ben Morrison. One of the main reasons for these crosses was to extend the season of azalea blooms by crossing early blooming azaleas with the larger flowered, later blooming species and hybrids.

Azaleas come in many forms and colors whether tall or short; large flowered or small flowered, evergreen or deciduous. The deciduous azaleas (those that lose leaves in the winter) often have colors generally not seen in the evergreen azaleas. Many of the deciduous azaleas have flowers that are orange or yellow. The interesting thing is that the oranges and yellows are often the product of azaleas native to eastern North America, whereas the magenta, red, salmon and purple azaleas are products of species from Japan, Korea and China.

See you in the garden!

Click here for images of the collection.

You can also read the Azalea Blossom Watch from
, 2014, 2013, 2012, 2011, 2010, 2009, 2008, 2007, 2006, 2005, and 2004.

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Last Updated   April 28, 2016 12:00 PM

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