A WORD OR TWO ABOUT GARDENING

A foolproof way to brighten a dull yard

If your yard strikes you as a m onotonous sea of green the one certain recipe for relief is a few judiciously chosen w hite flow ering . You don’t need to know anything about the appropriate use of contrasting or com plem entary colors as it applies to landscaping. White is the one color that can be used safely in any part of the garden: to focus attention as a stand alone specim en or to fram e or divide other elem ents of the landscape. It is not difficult to find w hite flow ering plants: for seasonal use as bedding plants m ost garden centers w ill have im patiens, w ax begonias or petunias plus m ore perm anent favorites such as gardenias and peace lilies (spathiphyllum s). M any popular shrubs are available in w hite flow ering form s including crepe m yrtle, oleander, brugm ansias (angel’s trum pet) and m any classes of roses. Even som e of M iam i-Dade’s m ore popular sub-tropical shrubs are available in w hite flow ering form s: Plumbago auriculata ‘Alba’ (w hite plum bago), chenille plant (Acalypha hispida ‘Alba”), golden dew drop (Duranta erecta) and the pow derpuff (Caliandra haematocephala ‘Alba’). If it is clim bing plants that you interest you, look no further than bougainvilleas w ith cultivars such as ‘Snow White’, ‘Jam aica White’, ‘M iss Alice’ and ‘M auna Kea White’. As w ith previous articles dealing w ith garden color, archived at http://miami-dade.ifas.ufl.edu/publications.htm, the em phasis is on plants w ith at least som e degree of perm anency in the landscape. Apart from the above item s there are other less fam iliar w hite flowering trees, shrubs and clim bers that can be used in M iam i-Dade. Those described below cover a range of landscaping situations. If you have space for a large (40’) w hite flow ering specim en tree w ith an extensive root system consider the im pressive w hite floss silk tree (Ceiba insignis), a cousin of the fam iliar pink flow ering floss silk tree (chorisia). The tree has a green sw ollen trunk covered with cone shaped thorns and flow ers in the fall w hen the tree is bare. Each flow er has 5 oblong to ovate 3” w hite petals, w ith a yellow throat and is follow ed by large w oody seed capsule filled w ith m any fine silky fibers (can be m essy). Look for grafted trees to ensure early onset of bloom ing. Another large tree w ith w hite flowers that is occasionally seen in M iam i- Dade landscapes is the elephant apple or hondapara (Dillenia indica). The flowers are large, pendant, cup-shaped w ith large w hite petals and m ildly fragrant, a perfect foil to the dark green deeply veined leaves. The tree can grow to 40 -50’, developing a trunk w ith attractive red, peeling bark. The one disadvantage (for som e) is the outsized rather m essy fruit, purported to be edible if you can overcom e the strong odor. Grow in full sun and evenly m oist soil - in M iam i-Dade it w ill probably be necessary to correct for trace elem ent deficiency sym ptom s. In general m agnolias do not grow w ell in M iam i-Dade, though if you have an area w ith enriched perm anently m oist soil you could try the native sw eetbay m agnolia (M agnolia virginiana), found scattered at ham m ock m argins in the Everglades. The flow ers are sm all for a m agnolia but fragrant and the leaves arom atic w ith a conspicuous silvery underside. If you attem pt to grow m agnolias in M iam i-Dade use plenty of m ulch, and correct expected trace elem ent deficiencies. Scale insects are frequently a problem . The popular dw arf M . grandiflora ‘Little Gem ’ is best grow n in a container (large tub or planter) in M iam i-Dade. Useful for a patio, but leaf drop can be a nuisance near a pool. Also in the M agnoliaceae, but decidedly m ore tropical, M ichelia x alba (a w hite hybrid form of M ichelia champaca, som etim es know n as the w hite cham paca)) is better adapted to M iam i-Dade than m agnolia. It is grow n for the glossy green foliage, and the pleasantly fragrant, attractive w hite flow ers. The tree grow s to about 25 – 30’ and can tolerate drier soils than m agnolia, but w ill require trace elem ent supplem ents, particularly iron. As w ith m agnolias, scale insects can also be a problem . The w hite cham paca w ill not tolerate root disturbance, so choose a place in your landscape carefully - once in the ground it should not be transplanted. M ore often seen than the above trees is the w hite flow ering orchid tree, Bauhinia variegata ‘Candida’, the leafless tree m ost im pressive in flow er against a clear blue early spring sky. Som etim es listed as B. variegata ‘Alba’, ones enthusiasm is tem pered by the tree’s often w eedy, m essy habit and w eak w ood. Like other bauhinias is susceptible to potassium and iron deficiencies. If you prefer a sm aller, w hite flow ering tree, then the Texas w ild olive (Cordia boissieri (locally know n as the w hite Geiger) is gaining in popularity. Throughout the w arm er m onths of the year, the tree produces chalk w hite flow ers w ith crinkled petals against rough surfaced 4-6” grey-green leaves. Unlike the m ore w idely planted orange Geiger (C. sebestena), the foliage of C. boissieri is not disfigured by the Geiger tree beetle. It is essential to choose a full sun site w ith perfectly draining soil, and once established keep the soil relatively dry. There are other w hite flow ering cordias, one of w hich (C. superba, locally of lim ited availability) is claim ed to be better adapted to M iam i-Dade’s w et sum m er clim ate. Less w idely planted, the fried egg tree (Oncoba spinosa) like C. boissieri requires m inim al care and can be m aintained at no m ore than 15 -20’. The tree has 3” serrated leaves, pinkish red at first, becom ing dark green and is heavily arm ed w ith stout 1-2¼” spines. In late spring through sum m er, particularly after heavy rainfall, the tree produces 2-3” w hite cam ellia like flowers w ith a large central ‘yolk’ of prom inent yellow stam ens. Individual flow ers last little m ore than a day, but apart from the visual appeal have a delicious m elon like fragrance. Endem ic to areas of dry open w oodland of E. Africa, this is a tough tree that exhibits excellent drought tolerance. The tree is sem i-deciduous, leaf loss depending on the extent of cold w eather exposure. Avoid heavy pruning as this w ill induce pronounced suckering. One of the m ost exquisite sm all w hite flowering trees is the im pressive Portlandia grandifolia (bellflow er). Of lim ited availability (difficult to propagate), it is native to Jam aica’s cockpit country (lim estone karst) as a rarely found under story plant. The new leaves are at first w ine colored becom ing a glossy m id to deep green. With the rainfall and rising tem peratures of spring, large pleated cone shaped buds form , opening into stunning, w hite 6-7” elongated bell shaped flow ers. The flow ers resem ble an Easter lily, but have a satiny sheen and em it a sw eet vanilla fragrance at night. Initially developing top grow th on a single thin stem , the base eventually fills out and despite a slow rate of grow th, flow ering com m ences w ithin 2 years. Depending on how it is pruned, P. grandiflora can be grow n as a sm all (10 -15’) tree or shrub. Choose a sheltered site w ith som e light afternoon shade (im proves flow er quality) and keep soil evenly m oist during w arm er m onths of the year w ith only occasional w atering in w inter. During periods of cold w eather leaves w ill becom e discolored (reddish brow n blotches). This is an ideal container plant for a patio. The fam ily contains m any w hite flow ering shrubs, trees and vines of w hich the best know n are the plum erias (frangipanis). There are w hite cultivars of the fam iliar Plumeria rubra such as ‘Bridal White’ as w ell as less fam iliar w hite flow ering (P. alba and P. obtusa- com m only called Singapore w hite). Of com paratively recent interest P. pudica (bridal boquet) grow s to about 12’. It has panicles of intensely w hite, funnel-form flow ers w ith a yellow throat and unusual spathulate (spoon-shaped) leaves. Although not fragrant, this species has the distinct advantage of being resistant to frangipani rust. The salt tolerance and com pact grow th m ake it an ideal choice for coastal gardens. Another m em ber of the Apocynaceae that is w ell adapted to coastal landscapes is Ochrosia elliptica, a 15’ shrub or sm all tree w ith w horls of thick shiny leaves and in fall, clusters of sm all w hite fragrant flow ers. Although both salt and drought tolerant there is concern that this tree can be invasive, at least in coastal locations. The flow ers are follow ed by num erous paired bright red plum -like fruit. Bew are - although highly ornam ental, the fruit is very poisonous. Ochrosia elliptica is som etim e m isleadingly referred to by the com m on nam e kopsia, w hich is actually the nam e of a related of trees and shrubs. Kopsia pruniformis has larger, w hite, pinw heel like flow ers than O. elliptica and purplish blue fruit (also poisonous) and can easily be distinguished by its’ paired leaves.. Pinw heel shaped flow ers are a feature of another m em ber of the Apocynaceae, the popular Carissa macrocarpa (Natal plum ). This is a slow grow ing spraw ling shrub w ith sm all spine-tipped glossy green leaves and stem s w ith forked spines in the leaf axils. An ideal choice for coastal plantings, especially as a barrier shrub, it can also tolerate salt and drought as w ell as partial shade (providing there is good air circulation). The decorative red fruit, unlike the tw o above plants, is edible (som etim es referred to as straw berries and cream ). Far less w ell know n m em bers of the Apocynaceae are shrubs and trees in the genus W rightia w hich have only recently stim ulated som e local interest. The w ater jasm ine (W . religiosa) is a sm all (to 10’) slow grow ing tree w ith thin branches, sim ple 2” leaves, and m ildly fragrant dim inutive w hite flow ers that hang in clusters like snow drops. Provide m oist but free draining soil and grow in full sun to light shade. The sm aller W . antidysenterica is a slow grow ing shrub som etim es referred to as m ilky w ay or snow flake, w ith larger intensely w hite, star shaped flow ers. This is a very effective shrub, especially w hen three or four are grouped together. In addition to m oisture it prefers acid soils so it w ill be necessary to correct for trace elem ent deficiencies, particularly iron. Incidentally the specific epithet antidysenterica refers to a rare alkaloid present in the plant used as a cure for dysentery. For particularly showy flow ers, tw o further closely related m em bers of the Apocynaceae, are especially w orthy of consideration. First is Stemmadenia littoralis (lecheso), a sm all (20’) tree that is becom ing increasingly popular for both the 8” glossy leaves and fragrant 4” w hite salverform flow ers. Native to coastal forests of Central Am erica, lecheso exhibits good salt tolerance and is m oderately drought tolerant. Although grow ing in full sun, som e light afternoon shade is beneficial in late spring to sum m er. The related pinw heel jasm ine, Tabernaemontana divaricata is a 6 - 10’ shrub w ith glossy, prom inently veined leaves. The w hite, propeller shaped flowers have five broad petals w ith a sm all yellow center and are pleasantly fragrant at night. The cv. ‘Flore Plena’ has double flow ers and is com m only know n as crepe jasm ine, or in the past as Florida gardenia. It us a good substitute for the com m on gardenia, being less prone to nutritional problem s. The cv. ‘Grandifolia’, in addition to double flow ers, also has larger leaves and is especially effective when grow n as a sm all tree. Choose a site in full sun preferably w ith som e light afternoon shade, and grow in enriched m oist soil. Com pared to lecheso, T. divaricata is not as tolerant of salt or dry soil and should be w atered during periods of hot dry w eather. In w inter som e leaf drop is to be expected for both plants during cold w eather. Several shrubs have m odified leaf-like structures, bracts or enlarged sepals that contribute color rather than the true flow er. Bougainvilleas are one of the best know n exam ples but there are m any others. From early Novem ber through Decem ber as it flow ers, the m any cyathophylls (bracts) convert Euphorbia leucocephala (little Christm as flower) from an ordinary 8- 10 shrub into a giant ball of w hite lace. Grow E. leucocephala in full sun in a free draining soil. During the w arm er m onths of the year m ussaendas can be the source of continuous color in the landscape. This is due to one or m ore specially enlarged sepals (calycophlls). An outstanding w hite form is M ussaenda philippica ‘Dona Aurorae’, a spraw ling shrub grow ing to m ore than 10’. Sm aller and m ore com pact Pseudomussaenda flava can be m aintained at less than 5’ and grow n in groups of 3 -4. M ussaendas require enriched m oist soil (keep m ulched) and benefit from som e light afternoon shade. Before concluding this m onth’s article, w e double back to the Apocynacee to consider three outstanding vines - flow ering vines are under utilized in local landscapes. If you have room and can provide a large sturdy support, herald’s trum pet (Beaumontia grandiflora) is a m agnificent w oody vine/liana w ith large glossy leaves and fragrant, w hite, 7” trum pet shaped flowers having flared som ew hat crinkled lobes. The flowers resem ble those of the Portlandia above but are not as stiff w ith m ore distinct reflexed lobes. Prune lightly after flow ering (flow ering occurs on previous seasons w ood). Grow in m oist soil w ith a full sun exposure. Where space is lim ited substitute the yellow throated w hite flow ers of M andevilla boliviensis, a vine m ost am enable to container culture (the only option if you have problem s w ith parasitic soil nem atodes). Provide an arch or 6’ trellis and keep the roots cool (m ulch) and provide som e shade from hot afternoon sun. M andevillas have brittle fleshy roots that are easily dam aged and for this reason once established they should not be transplanted. The final vine, the bridal vine ( floribunda) is an old tim e favorite that is a little less finicky than M andevilla as to grow ing conditions. Like M andevilla the roots need to be kept cool w hile the top grow th benefits from som e high dappled shade during the sum m er. M aintain even m oisture, allow ing the soil to dry out som ew hat in w inter (expect som e leaves to yellow and drop). Prune lightly during late w inter rem oving shriveled stem s and those w ith yellow ing leaves (cut back to a node). As days lengthen and nights becom e w arm er enjoy the clusters of sw eetly fragrant, w hite, w axy salverform flow ers as a rew ard for your diligence.

John M cLaughlin June 21, 2005