Thursday, September 25, 2008
Japanese Pagoda tree is a great option
John Arbogast
Landscape consultant John Arbogast answers your questions every Thursday. Send questions about your lawn, garden, plants, or insects to:
Dear John
5102 Greenfield St. SW
Roanoke, Va. 24018
Or send an e-mail. Answers will be given only in this column. Please don't send pictures or samples.
Recent columns
Q: You have mentioned the Japanese Pagoda Tree previously. I’m interested in this tree for planting next spring in my fairly large, open front yard about 25 feet or so from my corner property line and many feet away from my house. I saw one of the Japanese Pagoda Trees here in central Virginia when I was on a short trip in July, and it was beautiful. Please tell me more about it and give your opinion on Japanese Pagoda Trees.
A: The Japanese Pagodatree (botanic name Sophora japonica) is great for use in the landscape in areas were the summers don’t get excruciatingly hot in U.S.D.A. Hardiness Zones 4 to 8 (Roanoke is in Zone 7, but places near here in the higher elevations of the New River Valley and in West Virginia are in Zone 6. I love the Japanese Pagodatree because of its upright spreading yet broadly rounded shape; its handsome 7 to 10 inch long compound leaves composed of many smaller leaflets growing out of a long central stem; its medium to fast growth rate; its tolerance of heat, poor soils, and drought after establishment; and its creamy white to yellow flowers that dangle from the end of the branches in midsummer.
A Japanese Pagodatree would make a wonderful “picture frame” end for your house if that front corner of the yard has enough room for a big tree. The Japanese Pagodatree can grow to a height of 50 to 75 feet with a similar width, although the exact dimensions can vary.
A Japanese Pagodatree’s leaves are a gorgeous, shiny green color that holds on into the fall, but unfortunately the leaves don’t develop much fall color.
The midsummer Japanese Pagodatree flowers are beautiful dangling accents when few other trees offer color to the landscape. The long flower clusters are still attractive in my opinion when they ripen into 3 to 8 inch-long green pods that turn to yellow pods and finally to yellow-brown pods that stick around for a long time.
The Japanese Pagodatree could be one of the best trees (my opinion again) for city conditions, for its ability to survive droughts after it is well established, and for planting in places where the soil is just not too good.
I understand that there are a few different cultivated varieties of Japanese Pagodatree on the landscape market. These varieties offer different characteristics, such as a weeping Japanese Pagodatree that I have heard about but not seen.
Q: Please explain to me and my beautification council why trees seem to grow better with a ring of mulch around them that should be expanded to include the total area under the tree’s branches as the tree grows rather than just having grass growing right up to tree trunks. Your answer will help settle a debate in my circle of friends as well as provide an answer to me and other Virginia Tech parents who saw who saw a big area of soil and mulch with no grass under the branch area of a big, old, sick-looking maple or oak near one of the Tech dorms.
A: A shallow-bowl-shaped ring of organic mulch around newly planted landscape trees is there because of the goals or purposes of organic mulch in general, and those will include helping to keep moisture in the newly introduced root ball, preventing weed growth near the new tree that will compete with the young and somewhat limited roots of a newly moved woody plant, formation of a saucer-shaped short bowl that holds the weekly water and lets it seep down into the root area, keeping the roots a little cooler, and we can’t forget beautification. To perform all these jobs, the organic mulch ring should be a saucer shape with thickness (based on Roanoke’s clay soils) of no deeper than 2 ½ inches near the rim of the saucer sloping down to a depth of only ½ inch near the trunk.
An important tree health reason for a ring of mulch around trees is to keep the lawn mower and the weed whacker away from trunks where bumps and cuts can easily occur and openings are created which serve as doors in the trunk for disease and decay organisms to enter, and an invitation goes out to certain pests to enter the trunk for eating or for reproduction places. A good example of this last opportunity are dogwood trunk borers, which gain entrance to dogwood trunks and dry wood inside mower and weed whacker injuries.
Please be sure to have your fellow Hokie parents read this answer and know that elimination of all plants, especially grasses, weeds, and ground covers is a critical method in eliminating competition to give the desirable tree all the water and nutrients from the soil under the tree’s branches.
This last reason is why tree fruit growers sometimes eliminate all grass and weeds in a wide strip in which young fruit trees are planted.
