10 July 2008

Rhododendrons in Lendonwood Gardens

Dr. Leonard Miller Knows Rhododendrons
Rhododendrons are members of the Heath plant family, a large collection of thousands of evergreen and deciduous shrubs that includes Azaleas.

Gardeners distinguish between rhododendrons and azaleas but plant botanists do not. Usually, rhododendrons are evergreen and usually azaleas are deciduous. There are other distinctions between the two in the leaf shape, number of stamens, etc.

What they have in common is a wide range of flower colors and their growing needs.

Past president of the American Rhododendron Society, Len Miller, has a collection of 300-rhododendrons at his Lendonwood Gardens in Grove OK.

Miller said that anyone who wants to grow rhododendrons in Oklahoma has to realize that all growing conditions have to be met and all are essential. He outlined those conditions as acid soil, moisture and drainage.

"Their natural growing location is on the northern slope of a mountain," Miller said. "They have to be well protected in Oklahoma in order to be successful."

According to Miller, rhododendrons can grow well here tucked under trees where they receive a maximum of 2-hours of morning sun and no afternoon sun, ever.

"Go out at 4:00 in the afternoon on a summer day to make sure the location receives no direct sun between 3 and 7," Miller said.

Rhododendrons need acidic soil and Miller urges anyone who wants to grow them to get their soil tested and amend the soil to achieve a pH of 5.5 before planting any shrubs.

"In my beds of established plants, the soil gets up to a pH of 6.2 to 6.5," said Miller. "I add sulphur at the rate of 1-pound per 100-square feet to acidify it. A cup of sulphur sprinkled on the ground (not dug in) around each plant will do it."

Miller said that rhododendrons have fibrous surface roots that are damaged by any digging around them. All of the plants' roots are in the top 6 to 8-inches of ground.

The soil has to be kept moist all year and the plants should be well mulched with pine bark mulch, not peat moss. Water rhododendrons when they are flowering, after flowering, during dry periods and late fall before the first freeze. Long, dry spells will require a soaker hose to get the moisture down 8-inches deep.

To plant a new shrub, Miller said to dig a hole 5-feet wide and 8-inches deep. Mix 6-cubic feet of pine mulch with the soil removed from the planting hole. Fill the hole and pile the pine-bark soil to make a raised planting area.

Remove the plant from the pot and cut the root ball in half. Spread the roots out, butterfly fashion. Plant the shrub above the soil level on 3 to 4-inches of pine-soil. It is a good idea to score and tease out the roots before planting.

Since rhododendrons' native location in on sharply drained mountain sites, drainage is key to success. The northeast side of the house is a good location.

"Sixty percent of the rhododendrons sold in Oklahoma will not grow here," Miller said. "Anyone who wants to grow rhododendrons should visit Lendonwood Gardens or other Oklahoma botanic gardens to see what is growing well."

Miller also suggested that potential growers do an Internet search for Taiwan hybrids and plant them in the winter.

"The Taiwan species and hybrids are a cross between hardy rhododendrons with those from the tropics so they can survive Oklahoma's hot humid summers," Miller said. "Rare Find Nursery sells the best ones for our area." (www.rarefindnursery.com)

Also, Miller is working on releasing hybrids for Oklahoma. One of the cultivars he recommends, Peppermint Twist, is available from Rare Find Nursery. It is described as having red buds, opening to rose pink flowers with red flecks in the throat and a white circle in the throat, which slowly grows larger each day. The leaves are glossy, dark green. A vigorous, compact, sweet rhody.

"Don't feel bad if your rhododendron dies," Miller said. "The nurseries sell what they can get and push them off as annuals."

Miller’s best advice is to visit his Lendonwood Gardens in Grove, look at the rhododendron gardens there and pick the varieties you like the best. Even on a 95-degree summer day, the shaded gardens are a relaxing oasis.

Dr. Miller began working on the garden soon after he returned from a tour of duty in Viet Nam 35-years ago. Lendonwood became a non-profit corporation 12 years ago.

Later, his family home and additional land were added to the public area. There are 300 specimens in the Rhododendron collection, one of the largest collections of false cypress in the country, 500 daylily varieties, 125 hosta varieties, 75-Japanese Maple species.

If You Go
Lendonwood Gardens is at 1308 West 13th Street (Har-Ber Road). Open every day from dusk to dawn. Adults $5 donation. Directions: From U.S. 412 take the Jay exit North on U. S. 59. In Grove, turn left onto Har-Ber Rd. More information www.lendonwood.org and 918-786-2938 or 786-8375. For wedding rental contact Teesha Kolczun at 918-787-9952.


Bobbi said...

I'm working on a new shade garden and I've planted some rhododendrons. They go really well with hostas as a ground cover.

Martha/All the Dirt said...

Which varieties did you plant, Bobbi? And, how many rhododendrons?

Do you already have a watering system in place? What works best?