Free-blooming Shrubs for Lime-free Soils and Pot Culture
( Aza’lea ) . Botanists now classify all plants they once call Azaleas as Rhododendrons . Garden lovers still use Azalea for deciduous or leaf - losing variety and for a few that are not , and the name Rhododendron for evergreen variety which have large , leathery leaf . In the treatment that follows , Azalea is used as a common name and Rhododendron as the scientific name , thus , when a species is constitute it is written , for example , R. calendulaceum alternatively of A. calendulacea .
azalea are hardy and tender outpouring and other summer - flower shrubs , aboriginal chiefly of North America and eastern Asia . They belong to the Heather family , Ericaceae . The name is derived fromazaleos , entail ironic or arid , an allusion to their home ground as first described by the earliest .
General Care
azalea demand ample supply of moisture but will not survive if the dirt is constantly waterlogged or is subject to flooding . In dry weather the soil should be soundly soaked at about weekly intervals .
unconstipated ( which normally think of once a yr , in spring before Modern increase begins ) fertilizing promotes good ontogenesis . Good fertilizers for Azaleas include cottonseed meal , soybean repast , tankage , old well - decompose manure and commercial-grade fertiliser prepared particularly for Azaleas , Rhododendrons , Camellias and other acid grease plant life .
The maintenance of a three - in rich mulch of organic fabric over the surface of the soil beneath Azaleas is very important . These are surface - rootle shrub and such a natural covering protects the roots from excessive hotness in summer and excessive cold in winter as well as from harmful drying . desirable mulch materials are leaf mold , coarse peat moss , coarse compost , bagasse ( lucre cane refuse ) , peanut hulls , earth corncobs , decayed sawdust and wood cow dung . If any of these are employ in a fresh rather than in a well - decayed term it is important to add at the same time a plant food that provides promptly available N .
Under no portion should one interrupt the land around Azaleas by delve , cultivate or hoeing . Weeds that come through the mulch should be deal pulled . Ordinarily , these will be few in number and will not demonstrate much fuss .
The old flowers of Azaleas should be removed as presently as they fade , except a few that may be left to give seeds , if these are wanted ; if many semen pods are allowed to form , flower bud may not develop for next twelvemonth ’s blooms .
Azaleas are dependent to a issue of pests and diseases . They are also open to a yellowing of the leaf make by iron chlorosis
Pruning
Azaleas require little pruning . Most are best if this is confined to the remotion of idle , dying or broken branches and to the cut out of branches that obstruct route or driveway . The occasional removal of some of the sure-enough and less careful branch of Ghent , Mollis , Knap Hill and like leaf - losing ( deciduous ) Azaleas encourages new vigorous growth from the base ( especially if the plants are fertilize as well as pruned ) . azalea of the Kurume case may be ( and ofttimes are ) shearedannually to more or less formal human body immediately after flowering , but under this treatment , they do not develop their natural and more beautiful use of growth .
When to Take Cuttings
The half - ripe or semi - woody shoots of the current year ’s growth allow for the good cuttings . The cuttings , 2 - 3 in . long , are taken off with a very tenuous heel or small-arm of the old branch during July and are found in a mixture of sand and peat moss in a frame or greenhouse . If a small bottom heat is available it is an reward . The frame is kept close for three or four week to further the thinning to organise ancestor ; the press cutting are watered after intromission and are afterward kept moist by syringe daily . Not all Azaleas origin satisfactorily from cuttings ; the Kurume eccentric are particularly well-fixed , many aboriginal American kinds notoriously difficult .
Layering and Grafting
Propagation is also carried out by layer the lower branches in summer . This is a method adopted for increasing the named varieties of Mollis and Ghent Azaleas as these do not amount true from seeds . The named kind are also increase by grafting , the common yellowness Azalea pontica being used as a lineage . This method acting is decline in favor because unassailable suckers not infrequently grow from the broth and , unless pulled off in time , finally overpower the named kind and kill it .
Native American Azaleas
The natural plant life of North America include a bit of Azaleas , many of great beauty and splendid for garden role . Most of these are natives of the East but one , R. occidentale , is find naturally from southern Oregon to southerly California , and another , R. albiflorum , in the Rocky Mountain region . The latter is generally not acceptable in cultivation away from its native habitat , but R.occidentale is one of the fine of native Azaleas . unluckily , it is not hardy where winters are severe ; it is planted in West Coast garden .
R. occidentale is a varying industrial plant , its flowers , which are larger than those of other American aborigine , are usually clean with a lily-livered splotch but sometimes are pinkish . They are give birth in spring just as the Modern foliage is develop . In twilight the leaves colouration handsomely . This Azalea hit a tallness of about 8 foot .
Of the Azaleas native to eastern North America the adopt are the most important from the gardener ’s point of view :
R. arborescens grows raging from Pennsylvania to Georgia and Alabama , where it occurs in upland and pot forest . It is hardy in the North and is a very excellent shrub . It discover a height of 10 - 12 foot . and sometimes up to 20 foot . and , in its distinctive form , bears whitened , fragrant flowers in belated spring . This kind is quite varying and some of its variants are likely to be fuddle with R. viscosum ( discussed later ) , although it usually blooms two or three hebdomad earlier than the latter and has prime with passably wider throats . It is commonly a more showy flora in bloom than R. viscosum and under favorable conditions attains a greater height.R.arborescens prefers moist stain .
The Flame Azalea , R.calendulaceum , is a indigen from Pennsylvania to Georgia and Kentucky in the mountain regions . It is a magnificent sort , very variable in colouring of flower , shape of flower and in other details . This kind is one of the parent species of the Ghent Hybrid Azaleas . It chance upon heights of 10 - 12 foot . or more . coloring of heyday varies from clear spark yellow to almost blood line - red , with every medium shade represented , and with the flowers of some plants bear witness miscellaneous color patterns . The flowers may be in relatively dense heads or in more loosely coiffure bunch . They are scentless , or nearly so , and are borne in tardy spring , jolly earlier than those ofR. arborescens and R. viscosum . This hardykind is perhaps the fine of eastern North American Azaleas . In culture in most parts of North America where it may be grown , it expand well and is very much longer - lived than the Ghent Azaleas . It prefers lite shade and will grow in desiccant soil than many Azaleas . In fall its foliation colors in shades of burnished yellow and bronze .
R.cumberlandense , a native of the spate of Virginia and North Carolina , closely resembles the forms of R. calendulacea that have deep crimson efflorescence . It blooms about two weeks later thanR.calendulaceum .
The Pinkshell Azalea . R. Vaseyi , sometimes call the Pinkshell Azalea , is a indigene of the Blue Ridge Mountains of North Carolina . It attains a maximal height of 12 - 15 foot . and is of notably upright habit of ontogeny . Its scentless flowers , which normally are unclouded pink spotted with light Brown University , are deep pink in bud , and appear in other bounce , just before the leafage expand . They are idle and graceful visual aspect , with their stamens very conspicuously maintain ( protruded from the heyday ) . This is the stout of native Azaleas and is recorded as hold temperatures at least as low as 30 degree below zero F. It prefer soil that is moderately moist , and is excellent for planting beside a lake or pool . In fall its leafage is beautifully discolour .
The White Swamp Honeysuckle . R.viscosum , the White Swamp Honeysuckle , or Swamp Azalea , grows as a native from Maine to South Carolina and Ohio and Tennessee in swamps . It attains height of 8 - 10 ft . and bears delightfully fragrant white , or much more rarely pinkish , flowers which are very decidedly sticky to the touch . Each is about an inch across and they are carried in cluster of 4 - 9 after the foliage has developed . This is the previous blooming of American Azaleas , and for this reasonableness is of special value ; its flowers are usually bloom in July .
R. viscosumis one of the parents of the Ghent Hybrid Azaleas . It is a variable kind and in its utmost form it is not always easy to distinguish it from figure ofR.arborescens , which see , above . Although a indigene of swamps and thriving in wet soils , it adapt itself remarkably well to somewhat drier locations and prospers in full sun .
R.roseum , by some botanists consider to be merely a form of R. nudiflorum , which it closely resembles , is , for garden purposes , superior to the latter . It hap of course from New England and central New York to Ohio and Virginia . It is a sturdy kind and is say to be more tolerant of limestone than any other American Azalea . R. roseum has flowers that are normally clear rose - pink in color , but plants with paler dark-skinned flush take place . The blooms are delightfully fragrant . This bush usually attains a height of 6 - 9 foot . The flowers unfold after the leaf is well developed , and the leaves assume strange shade of dark purple in fall .
Other native Azaleas ofeasternNorth Americainclude R. alabamense , a low , white - flowering sort that is a native of Alabama and peak there in mid - May . It is an inhabitant of teetotal Natalie Wood and is not dauntless in the North.R.atlanticum grows from southern Pennsylvania to Virginia and the Carolinas in the Coastal Plain region . Its fragrant flowers are livid or pallid pink and the plant is about 18 in . tall and costless - flowering . This sort is hardy in the North .
R. austrinum , not sturdy in the North , grows along river in southerly Georgia , Alabama and northern Florida and bears scandalmongering to orange and orangish - flushed , scented flowers in early outpouring . R. canescens , not suitable for planting in the North , populate Coastal Plain region from South Carolina to Florida . It more or less resemblesR.roseum but is less beautiful . Its flush run to be of washy pinkish coloring .
R. nudiflorum , the Pinxterbloom or Pinxter Flower , grows as a aboriginal from Maine to Florida and Texas . Its bloom , brook in springtime , just before the developing foliage , are pallid pinkish or rather impure white-hot and are inferior to those of R , roseum , which they resemble . It is fragrant but less so than R. roseum . This species is so like R. roseum that by some authorities it is regarded as a multifariousness of the latter . Intermediate form between R. nudiflorum and R. roseum occur .
R. prunifolium , aspecies aboriginal in southwestern Georgiaand easternAlabama , is not dauntless in the North . It has sizable red peak and grows about 8 ft . magniloquent .
The Chief Kinds for Planting Out of Doors.
Assuming that all soil essential are met , the factor that see the varieties or kinds to be planted is mood . sealed Azaleas will not tolerate extreme point of cold and others will not thrive in protracted summertime rut , specially in areas where there is no dependably continuous period of wintertime chilling , for all Azaleas require some wintertime balance .
All the specie aboriginal to North America are worth growing in gardens . All are deciduous ; many have fragrant flowers , some markedly so . There is a wide range of mountains of seasonal blush , with the earliest coming into peak as before long as ontogeny starts , and the last blooming at midsummer . mintage from elevations will maturate farther northerly than those from the southern coastal plains or northern Florida . The one specie native to the Pacific Coast , like most of its progeny , is not vigorous in the East , but is a splendid plant for the West Coast .
The European species , Rhododendron luteum ( the name Rhododendron is used because it is the correct botanical designation for all Azaleas ) , is excellent on the Pacific Coast but not always dependable in the East . It has brilliant scandalmongering flower and is delightfully fragrant .
The Asian deciduous species , R. japonicum from Japan , and the fairly standardized but less stale - resistant R. molle from China , are utile for lily-livered and orangish to orangish - violent color , have fine large heyday and have hybridise well . They are practically useless in the South . The Korean , R. Schlippenbachii , is one of the most magnificent of all Azaleas , reasonably stale repellent , but untested as yet in the South at small elevations . The coloration is the purest of pinks . Its foliage has skilful autumn colour . Two other specie , R. reticulatum from Japan and R. Mariesii from China , bloom , the first before and the second after R. Schlippenbachii , but are not so dramatic . The first , however , is fine when grown with early on - blooming Cherries and Redbud , and is of the same world-wide lavender - pinkish tone . The more southern R. Weyrichii is more of a pink-orange - red color but , while stalwart in cold climate , has not bloomed freely . The related to R. amagyanum has bloomed only on the Pacific Coast .
R. dauricum , from Siberia and Japan , is semi - evergreen plant where winters are not very severe . It grow 5 - 6 ft . high and bear rose - purple flowers in winter in mild climates , but blossoms in very earliest outflow where winters are abrasive . The nearly related R. mucronulatum , from China , is showy than R. dauricum . It forms a dense scrub , 3 - 4 foot . or more high , and bear pale , rosy - majestic flowers freely in wintertime or other spring , depending upon the mood .
Relatively few evergreen species are grown in their wild forms . With the exclusion of R. indicum , usually lie with as Azalea macrantha , and its several color forms and variants with modify corollas , and more rarely the Formosan R. oidhamii , few are found in garden . R. scabrum is in all probability the most spectacular , especially in its consummate red form , but it is sensible to cold and does not survive even in part of the South . R. serpyllifolium , especially in its white - flowered form , is charming when it has made its growth and is covered with lacelike small peak . The semi evergreen plant R. poukhanense , from Korea , is very cold - resistant and blooms freely specially when grown in sun , but because of its lavender - pink blossom , it need careful placement . It is ripe for fall coloring . R. Simsii and R. obtusum Kaempferi aresemi evergreen and insmall gardensare out - classed by their issue . R. mucronatum and its color variants are evergreen in the South , becoming increasingly more deciduous the further Frederick North it is used . It is largely outshone by its offspring in modern cross .
Rock Garden Azaleas
There are relatively few Azaleas that make mouse mat of twiglike branches such as one expects of rock garden material . If one wants an accent plant in the rock garden , however , any of the Kurume Azaleas will serve for this purpose . The one striking Azalea that does meet rock gardening requisite is R. indicum balsaminaeflorum , which is slow - develop , prostrate , and covered in June with doubled Salmon River - pink balsam - like bloom . In regions where they are hardy , the Nipponese clones ( varieties pass around vegetatively , not sexually ) known as Gumpo , Bunkwa , Gunrei and Gunbi are almost its equal and have even more spectacular though single flowers , in white , tinted Edward D. White and a pale salmon . These last are sometimes number among the Chugai hybrids , but not all variety so listed have this use of growing . Do not use Kurume Azaleas and gestate them to retain the low - growing contour that were described from the original high - muckle location in Japan , unless the garden is also on a mountain .
Hybrid Azalea Races or Groups .
These are many , and most of them contain plants with even more spectacular flowers than the species . Their origin are various and their purpose succeed the recommendations as impart . Several have become standard squeeze variety in the North and excellent garden flora in the South and on the Pacific Coast .
The Rutherfordiana Azaleas . These again hold back tender species in their parentage and in the South and on the Pacific Coast decently substitute the Kurume Azaleas and many of the Glenn Dale Azaleas . There is not so all-encompassing a people of color range in the Rutherfordiana clones as in the Glenn Dales , but there are single , hosepipe - in - hose and twofold - flowered clone , all excellent .
The Glenn Dale Azaleaswere breed for the Middle Atlantic States only , but some are testify utile further due north near the coast , and many are excellent in the South , where , as on the Pacific Coast , many are fall and winter - blooming without take away from the spring showing . They are not uniform in reproduction and embrace a panoptic range of gloss , form and season of blossom , with some colour and practice not found in any other hardy race . On the Pacific Coast , where Rutherfordiana and Belgian types can be turn , the Glenn Dales are not call for . Most are evergreen .
The Gable Azaleasrepresent another regional breeding project , for an surface area further inland and more northward . They should take the place of Glenn Dales in more northerly US , though they do not have so wide a color range nor so great a seasonal range . They do admit some superb doubles . Not all are completely evergreen .
Knap Hill Hybrids . These are innovative equivalents of the Ghent and Mollis hybrids . They are hybrids of R. Peruvian mastic tree , R. calendulaceum , R. occidentale and R. arborescens . The strain was originated by Waterer ’s at Knap Hill Nursery in England and was further uprise by other breeders , notably by Slocock ( England ) , Rothschild ( Exbury , England ) and Stead ( Ilam Estate , New Zealand ) . The four “ substrains ” raise by these breeders are cognize respectively as the Knap Hill , Slocock , Exbury and Ilam Azaleas . Varieties belonging to these strain have wide open flowers of excellent grain and total in a extensive range of colors . They are deciduous .
Indian or Indica Azaleas of the South . These are the surviving representatives of the early Azalea gentility in Europe , principally in Belgium . In their modern forms they are grown for push in the East and as garden plants in some parts of the Pacific Coast . There are perhaps about forty clones in cultivation , include some for which there is no name extant . They are evergreens , some perhaps species , many complex hybrid . Not all have R. indicum in their parentage . The color range is special , a little serial publication in the lavender to purple serial , and a shorter series in the salmon to scarlet serial . There are few whites , some of them bare or flaked with semblance . There are a few double . In most typeface , the caliber is second charge per unit , but the effects secured from well - grow specimens can be very fine .
Ghent Azaleas . These are deciduous Azaleas breed mostly in Europe near Ghent , and interpret the progeny obtained by get over the European yellowness Azalea with various American deciduous Azaleas . The color range is wide , from white through all pinkish to thick rose , some with yellow tints and many with yellow splotch on the upper lobe . Many are fragrant . There is a treble - flowered race that is usually list as R. rusticum flore - plenum . Many are not much better than the best forms of our own native Azaleas .
Mollis Hybrids . Originally these were hybrid between the American species , the EuropeanR.luteum , and the ChineseR.molle . They varied from the above race chiefly in larger flowers . Many were less cold - tolerant . With the intromission of the more insensate - resistant R. japonicum , there appeared hybrids between R. pepper tree and R. japonicum , most of which are fantabulous and some of which appear to have been raised with R. japonicum on the existing R. molle hybrids . There is a wide color range , but these hybrids are chiefly valued for the yellowed , orangish and scarlet tonality . The bloom are large and funnel - shape as compared with the Ghent hybrids , which have tubular flower with diminished open faces . There is little fragrance in this mathematical group and they are generally earlier inflorescence than the Ghents . Useless in the South , except at elevations .
Kurume Azaleas . These earlier were natural variants from the Japanese R. obtusum , and the original location was at high aggrandisement in southerly Japan . As garden industrial plant in Japan , they come in from low elevations and are wide develop . There is a wide range of colouration from consummate and tinct whites through pure pinks to rise , through lavender - pinks to empurple , and through Salmon River - pinks to scarlet . There are both single and hose in - hose types of rosiness . The paler colors appear to be less cold - insubordinate than cryptical - colored clon . There is no consummate report for the South but there seems to be no difficulty generally . Some of the more modern varieties listed as Kurumes appear to include other pedigree .
Pericat Azaleas . This is a small group of Azaleas said to have been breed between Kurumes and Florist ’s Azaleas ( Belgian or Indian ) . They vary in cold - resistance , and the larger - flowered form are the more striking .
For the Greenhouse
The evergreen plant Indian or Belgian Azaleas are decorative greenhouse shrubs . They brook a profusion of attractive flush which vagabond from clean through pink to rose and ruby , and may be single or double . These Azaleas are well forced into bloom in wintertime and early spring .
The most popular way of growing them is in the frame of swob - headed specimens or low touchstone on 6 - in . stems . They can , however , be trained as pyramids or as magniloquent standards on stems about 4 ft . high .
How to Begin . The best way to begin is to purchase plants well set with heyday buds in the autumn . The balls of soil and roots should be pricked over with a pointed stick to murder loose grease , the flora then being potted in flowerpots large enough to ply about an inch of fresh compost assail the roots ; the soil must be rammed fairly hard with a potting marijuana cigarette . After potting is finished , the plant are sic in a unripened house — temperature 50 - 55 degrees — and syringed oft to boost fresh growth .
It is not advisable to squeeze Azaleas into early bloom the first year , but in the 2nd and subsequent class , when they are well established in quite a little , they will withstand pressure much better . Plants in full bloom which are purchased from a florist ’s workshop in the spring often bomb afterward because they have been untimely pressure into flower in a warm greenhouse .
When to Repot . As soon as the blossom of Azaleas have faded , they must be move out and the plant turned out of their pots to allow the escaped soil to be polish off in the way already explained . They are . then repotted as advise , placed in a temperature of about 55 degree , and syringed day by day . This handling will encourage antecedent action and the formation of novel shoots . In May they should be bit by bit inure off .
set Them Out of Doors in Summer . When the weather becomes tender and fall , the plants are go under in a more or less shaded status out of doors , to encourage the formation of flower buds , the pots being plunged to the rims in a bed of ash . A biweekly dose of a fertilizer will also assist them to produce blooms freely . In October the azalea are placed in the glasshouse — minimum temperature 45 degree — and in the new year they may be forced into former bloom in a temperature of from 50 to 60 degrees .
The reason why many Azaleas grown in pots in the greenhouse do not flower freely is that they are not exposed fully to air and visible light during the summer month , and as a upshot , the buds do not mature . It is most necessary to put them out of room access .
Prune After Flowering . These Azaleas are rather irksome growing so they do not need repotting every class , but when the pots are full of tooth root , repotting should be done as presently as the flush have fade . Very little pruning is command ; long branches which have outgrow the others and tend to spoil the symmetry of the plants should be shorten when flowering is over .
When to Take press clipping . newspaper clipping are made from half - ripe ( half - woody ) shoots about 3 in . in length in July . They are inserted in pots of flaxen peat place under a bell jar in a nursery or skeleton — temperature 50 degrees ; the interior of the methamphetamine hydrochloride must be wiped every morn . The bell jarful is removed when , in the trend of a month or so , the cuttings are rooted , and a calendar week or two after the young plants are potted separately in 3 - in . pot . Subsequent treatment lie in of cutting back the main shoot of each plant when 6 in . high and abbreviate subsequent side shoot to ensure a well - balance specimen .
The Indian Azaleas . A lovely greenhouse variety is the evergreen Indian Azalea , Rhododendron indicum . There are legion mixture of which these are some of the best : Single - flowered , Mlle . Van Houtte , white flaked with rose ; and Reine des Fleurs , salmon . doubly - flowered , Deutsche Perle , white ; Vervaeneanum , salmon ; President Kerchove , Salmon River - pink , and Empress of India , pink and livid .
Other Azaleas for Greenhouses . Kurume Azaleas , Mollis Azaleas , Rutherfordianum Azaleas and some other eccentric are excellent plants for coerce into bloom in the glasshouse in early saltation .
For this purpose plant well set with flower buds should be hold in autumn . They are pot in October — November in pots just expectant enough to hold the root word . A compost of equal division of loam and leafage mildew , or lime - innocent dirt from the garden , is suited . After pot , they are plunged to the rim in a seam of ash tree out of room access .
How to get Early Blooms . Early in January , the plant are study into the glasshouse to force . For the first 3 or 4 weeks a temperature of 50 degrees is high enough , this being increased by 10 degree when the flower buds commence to well . By the program of greater heating , bloom can be produced earlier but very little foliation is develop and the bloom blow over promptly . A moist atmosphere must be maintained by regularly break the floor and scaffolding of the glasshouse , and the stem of the plants must be syringe doubly a daylight to help the bud in breaking . Under this discussion it take about 6 calendar week to force plants into bloom . To keep the peak in full sweetheart as long as possible the plants must be removed to a cooler lieu .
During the period of forcing and while the industrial plant are in bloom the soil must be kept moist . After flowering , the plants are keep in a cool frostproof planetary house until danger of terms by Robert Lee Frost is over , when they are replant in a reserve molding out of doors for a year or two to recuperate before being forced again .
AZALEA : COLORFUL IN SPRING AND AUTUMN
