A Trop­i­cal Op­tion

The Washington Post - - Gardening - By Scott Aker

QI no­ticed some in­ter­est­ing shrubs planted around the Na­tional Gallery of Art last sum­mer. They are woody with deep-yel­low bell- or trum­pet-shaped blooms. A friend with hor­ti­cul­tural knowl­edge iden­ti­fied them as Al­la­manda schot­tii, a trop­i­cal plant from Brazil. To me, the flow­ers look dif­fer­ent. If it is this plant, can it be planted as far north as Wash­ing­ton? AThe

plants you noted are a dif­fer­ent species, Al­la­manda cathar­tica. It has be­come fairly com­mon in land­scapes be­cause it flow­ers pro­fusely all sea­son long and is quite tol­er­ant of heat. It is tech­ni­cally a vine, but it sel­dom wan­ders much in our cli­mate.

There has been a move­ment to­ward trop­i­cals such as Al­la­manda in streetscap­es and door­yard ar­eas where bed­ding plants once pre­vailed. Trop­i­cals take up more space than reg­u­lar bed­ding plants, and thus it may be cost-ef­fec­tive, par­tic­u­larly when la­bor is fig­ured in, to plant a few large trop­i­cal plants than to plant scores of bed­ding plants in a given area. Trop­i­cals also sail through heat and bloom, even when con­fronted with the worst that sum­mer can give them. Tra­di­tional bed­ding plants of­ten take a break in mid­sum­mer.

Al­la­manda is not win­ter-hardy in our re­gion, and in most of the coun­try it is treated as an an­nual and re­planted ev­ery year. It would need bright light and cool con­di­tions in­doors to sur­vive the win­ter. We planted a tri­color beech tree three years ago. It is beau­ti­ful, and we love it, but now we re­al­ize it will get too big for our small prop­erty. Will it grow slowly enough to be all right, can we keep it down in size, or do we have to re­place it with a smaller tree?

Tri­color beech grows ex­ceed­ingly slowly, par­tic­u­larly in a hot site. Even in cooler con­di­tions, it is not a large tree, grow­ing to about 30 feet with a 20-foot spread af­ter many years. Tri­color beech will man­age only about six to eight inches of growth per year on av­er­age. You may have been look­ing at in­for­ma­tion re­lat­ing to the species Euro­pean beech, which can grow much larger, to 60 feet in height with a 40-foot spread. I have a patch of black mondo grass that has been dy­ing back se­verely over the past two years. Is this nor­mal, and will it re­ju­ve­nate?

The death may have been due to tem­per­a­ture ex­tremes, drought or pests. Al­though it is per­fectly hardy, mondo grass may re­spond to a sud­den cold snap with the death of leaves, par­tic­u­larly the old­est of the leaves around the mar­gins of in­di­vid­ual crowns. Mondo grass can take heat, but it needs a con­sis­tent sup­ply of mois­ture, and if the soil is al­lowed to be­come very dry, leaves may die back. This is more likely if the plant gets di­rect sun­light.

An­other po­ten­tial cause is fern scale, which you would find at the base of the leaves, par­tic­u­larly on the new growth. This pest can se­ri­ously stunt liri­ope and mondo grass. The pres­ence of ants may sig­nal scale be­cause the ants farm the in­sects for their sug­ary ex­cre­tion known as hon­ey­dew. Scale can be dif­fi­cult to kill be­cause they feed be­tween leaves that are tightly packed in the crown of the plant. Cut­ting in­fested fo­liage as close to the crown as pos­si­ble in spring and treat­ing new growth with a pes­ti­cide con­tain­ing acephate may help re­duce the num­ber of scale in­sects. If you don’t see new growth this spring, the plants are dead and should be re­placed.

Scott Aker is a hor­ti­cul­tur­ist at the U.S. Na­tional Ar­bore­tum.

BY AIS­LINN ADAMS FOR THE WASH­ING­TON POST

Al­la­manda cathar­tica.

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