JARS v47n2 - Hanging Basket Rhododendrons

Hanging Basket Rhododendrons
Richard Cavender
Sherwood, Oregon

There have been several articles over the past several years about using evergreen azaleas in hanging baskets. There are a number of vireya rhododendrons that also do very well in hanging baskets. Most people tend to think of vireyas as tall and straggly, but several of the small species and their hybrids have a branching and trailing habit. Most vireyas are epiphytes; they grow in the moss in the tops of trees and are better adapted to baskets than azaleas.
One of the best plants for me has been Rhododendron pauciflorum , a miss-named plant if ever there was one. The name implies shy flowering, but my 5 or 6-year-old plant has been in continuous bloom for over 18 months! It is growing in a 6-inch hanging basket and covers itself in flowers twice a year. The rest of the time there are always a few scattered about the plant. The flowers are not large, under 1 inch long and inch wide in trusses of two or three, but their bright waxy red color stands out against the pale green of the leaves. Once established, it needs very little pruning and it trails naturally. Young plants should be pinched several time to form a good foundation.
Another species that does well in a basket is R. jasminiflorum var. punctatum . As the name implies, the flowers are jasmine shaped - long thin trumpets with a flare of petals - and it is fragrant. Rhododendron jasminiflorum var. punctatum will cover itself a couple of times a year in trusses of six to ten and flowers of soft baby pink. It has a fragrance like Narcissus . Young plants will need to be pinched but it will branch nicely once blooming commences.

R. pauciflorum
R. pauciflorum
Photo by Richard Cavender

Australia's only native rhododendron, R. lochiae , is another species for hanging baskets. Rhododendron lochiae has larger leaves and flowers than the two previous and will need a bit more pruning. The flowers are scarlet-red 2-inch bells in trusses of two to seven. A well grown plant of R. lochiae will bloom almost continuously.
For flamboyant flowers, R. christii is the choice - an unusually brilliant combination of velvety red and clear yellow on a curved hanging tube. Rhododendron christii blooms young and has attractive foliage. There are upright and trailing forms available. The trailing form is best for basket culture.
Breeders in Australia and New Zealand are doing the most work with vireyas. Vireyas are well suited to their climate where they can be used in the landscape in many areas. Their hybrids are slowly making their way to this country. There are several active hybridizers in the United States, however. Pete Sullivan in San Francisco is perhaps the best known and most prolific. Pete was in charge of the nursery at Strybing Arboretum prior to his retirement. He has produced many fine hybrids and is still active.
'Saint Valentine' was one of Pete's early introductions from seed by Tom Lelliott, Australia. It is one of the best small hybrids available. A cross between R. lochiae and R. gracilentum , it combines the best of both. The shiny green leaves set off the bright red flowers and the twiggy habit lends itself to hanging basket culture. Pete recommends a "hedging every other year."
It should be noted that most vireyas root like weeds. It's a shame to waste good cuttings when you prune so why not root them and hook your friends and neighbors?
I have several unnamed hybrids by Pete Sullivan that are similar in habit and can be trained to a basket. Rhododendron wrightianum x 'Bellsar' #2 and R. wrightianum x R. lochiae are both red, R. lochiae x R. culminicola is salmon and R. wrightianum var. wrightianum x R. jasminiflorum is a fragrant pink. All need pinching while young and may need to be encouraged to trail at first. I use wire hooks to train the young branches and establish a foundation. Once blooming commences the need for pruning diminishes.
Vireyas seem to have a reputation as hard to grow. I think the major mistake most people make is over watering. As epiphytes, they are adapted to feast or famine in regards to water and fertilizer. They should be allowed to dry out between waterings, much like Jade or other succulent houseplants. They are also quite happy in small pots. As epiphytes, they are used to a restricted root run. Rhododendron pauciflorum will be happy in a 6-inch pot for many years.

R. suaveolens
R. suaveolens
Photo by E. White Smith

My parent plant of R. lochiae x R. culminicola is in a 10-inch basket and is over 3-feet in diameter. The absolute worst thing you can do to a vireya is put it in a big pot and water it every day!
I prefer hanging "planters" rather than baskets. "Planters" have a well inside the bottom of the container rather than a saucer on the outside. This helps to slow run-off. My soil mix ranges from pumice, bark, peat to pure coarse bark. Peter's 20-20-20 or Fish Fertilizer once a month is fine. We hang vireyas in the same conditions that fuchsias enjoy, the north or east side of the house. We take ours into the greenhouse in the winter. Vireyas will not tolerate freezing but they don't require lots of heat either! I run my greenhouse at about 40° F and they do fine. It has been my experience that the average home is too dry for vireyas to flourish. They need more humidity. Without a greenhouse, plant rooms, spa or hot tub rooms, etc., work well. Remember they will bloom in the winter as well, so don't hide them away. The thing to remember is that vireyas are rhododendrons! They will thrive if given conditions they like and the same general rules apply to vireyas as to hardy rhododendrons.

Sleumer, Dr. Herman, An Account of Rhododendrons in Malesia
Vireya Vine, E. White Smith Editor. Various issues.
The Bovees Nursery Catalog, 1992 edition.

Richard Cavender, a past contributor to the Journal, is the owner of Red's Rhodies. He is also District Director for ARS District 4.