STREPTOCARPUS

Although widespread in the African and Asian tropics and subtropics, most of the cultivated plants in this African violet family (Gesneriaceae) genus of around 130 species of annuals and perennials are natives of southern Africa. They are a very diverse group, ranging from tiny rosette-forming plants to others that produce just a single huge leaf. But despite this variation of form they share some features, especially among their flowers. The leaves are velvety, heavily veined, and slightly crinkled. The flowers are long-tubed, primroselike, and usually have 5 petals; they occur in heads on short upright stems. The genus name is of Greek origin, derived from streptos (twisted) and karpos (a fruit), referring to the unusual form of the spirally twisted fruits.


CULTIVATION


Cold tolerance varies, though none withstand more than the lightest frost. Plant in a bright but not sunny position that is warm and draft-free. The soil should be fertile, moist, humus-rich, and well-drained. Propagate by division, from leaf-petiole cuttings, or from seed.


Top Tip


Treat Streptocarpus plants similarly to Saintpaulia when grown indoors. Use an African violet potting mix and place in a bright but not too sunny spot.

STOKESIA

Although there is just 1 species in this daisy family (Asteraceae) genus, it has been extensively developed in cultivation and is now available in a wide range of plant sizes, flower colors, and forms. A summer- to autumn-flowering perennial from the south-eastern U.S.A., Stokesia-or Stokes' aster-was named for Dr.Jonathan Stokes (1755-1831), English doctor and botanist. It arrived in England in 1766 and was in vogue in Victorian times, especially as a cut flower. It later languished but is now popular again. Stokesia is an upright plant with simple ever-green leaves borne in basal rosettes and large cornflowerlike heads of white, yellow, or mauve to deep purple-blue flowers. Stokesia plants are well suited to herbaceous borders.


CULTIVATION


Plant in full or half sun in light free-draining soil. Water and feed well. Watch for mildew in late summer. Propagate by division near the end of the dormant period, or raise from seed.


Top Tip


To prolong the Stokesia flowering season, remove the spent flower stems immediately. This cornflower look-alike is ideal for cutting and drying.

SPIRAEA

This genus consists of about 70 species of mainly deciduous, but sometimes semi-evergreen, flowering shrubs from the rose family (Rosaceae). They are found in many northern temperate areas, mainly in eastern and southeastern Asia, as well as in North America. Plants are highly appreciated for their flowering and foliage qualities. Leaves are simple and alternate, variously toothed and lobed, and may have gray or blue-gray downy undersides. Many species have attractive golden, orange, or bronze foliage over autumn. Flowers are borne in dense profusions in clusters, on terminal panicles, or along branch tips in spring or summer. The color range is generally white, yellow, pink, or crimson. The genus Spiraea is commonly known as bridal wreath.


CULTIVATION


They thrive in most soils, though some grow poorly on chalk, and prefer a sunny position and cool moist conditions. For prunning purposes, these plants fall into 2 groups: those that flower on the current year's growth, which can be hard pruned in spring, and those that flower on the previous year's growth, which should have old flowering shoots removed just after flowering. Propagation is from soft-tip or half-hardened cuttings in summer.


Top Tip


A second bloom will occur if spent flower clusters are removed after the first flowering. However, the second bloom will be less profuse.

SPARAXIS

A South African genus of 6 species of corms of the iris family (Iridaceae), Sparaxis plants will naturalize and form large drifts of brightly colored flowers under suitable conditions. The leaves are grassy to sword-shaped, with prominent ribbing, and develop quickly from late winter. They are soon flowed by wiry spikes carrying anywhere from just a few blooms to fanlike sprys of funnel-shaped 6-petalled flowers. The flowers may be white, yellow, or shades of pink to orange and red, usually with a yellow center and contrasting dark colors in the throat. The genus name comes from the Greek word sparasso (to tear), referring to the lacerated bracts at the base of the flowers.


CULTIVATION


These plants are not hardy where the soil freezes but are otherwise easily grown in full sun with fertile, moist, well-drained soil. In cold areas they can be lifted in autumn and replanted in early spring for a later flower show. Propagate from seed or by division.


Top Tip


Sparaxis species are suitable for the front of borders or in raised beds. In cold areas they may need to be placed in a greenhouse, or planted against a sunny wall, protected from wind.

SOLIDAGO

Although a few species are dotted in other temperate regions, this daisy family (Asteraceae) genus of around 100 specie of perennials is primarily North American. They form clumps of upright, sometimes branching stems, the upper half of which bear panicles of tiny golden yellow flowers; these have earned the plant the common name of goldenrod. The leaves may be lance-shaped, linear, or a pointed oval shape, and often have toothed edges. By the time flowering starts in late summer many of the lower leaves have withered somewhat. Native Americans used this lateflowering habit as a guide to when the corn would ripen. Solidago altissima is the state flower of Kentucky, and S.gigantea is the state flower of Nebraska.


CULTIVATION


Solidago plants are hardy and easily grown in full or half sun in any position with reasonably fertile, moit, well-drained soil. They will grow in poor soil and withstand drought but will not flower well or reach their maximum size with such conditions. Propagate by division, or from seed or basal cuttings. They may self-sow.


Top Tip


When selecting a Solidago plant for the garden, the named cultivars are preferable to the species because they are sturdier and less invasive.

SOLANUM

Famous for the humble potato (Solanum tuberosum) in its myriad forms, this genus includes some 1,400 species of often tuberous-rooted herbs, vines, shrubs, and trees that have a cosmopolitan distribution, with many from tropical America. The trees and shrubs may be evegreen or deciduous and many are armed with thorns. They are a variable lot but their flowers are all remarkably similar, being simple, small, 5-petalled structures carried singly or in clusters with a central cone of yellow stamens. Fleshy berries follow the flowers and are often the most brightly colored part of the plant. Some species have spherical fruit, while others have elongated fruit shaped like chilies. The berries are usually somewhat poisonous and, because of their conspicuous color, may be attractive to children.


CULTIVATION


These plants vary in hardiness, though few are really frost tolerant and most are quite tender. They are generally easily grown in any well-aerated well-drained soil. Most species prefer sun or partial shade. Propagate from seed or cuttings, or in a few cases by division.


Top Tip


The climing Solanum species can be trained to grow over atall trees, pergolas, and eaves, or against a sunny wall.

SINNINGIA

Named for Wilhelm Sinning (1792-1874), a horticulturalist and botanist at the University of Bonn, this African violet family (Gesneriaceae) genus is made up of about 40 species of tuberous perennials and small shrubs distributed from Mexico to Argentina. The commonly cultivated species are perennials with large lance- to heart-shaped leaves made velvety by a dense covering of fine hairs. The well-known florist's gloxinia (Sinningia speciosa) has large, upward-facing, bell-shaped flowers, although other species have tubular flowers and are sometimes scented. Their vivid showy flowers make the plants ideal for the house or green-house, as well as being lovely summer annuals or year-round plants in subtropical to tropical areas. 


CULTIVATION


They prefer warm humid conditions with a bright but not overly sunny exposure. The soil should be well-drained, moist, and humus-rich. Propagate by lifting and dividing after the foliage has died back, from seed, or by leaf-petiole cuttings. The tubers may be stored dry.


Top Tip


As indoor pot plants, Sinningia species will benefit from half-strength high-potash fertilizer applied every few weeks during the growing season.

SEDUM

This genus of over 300 species of succulent annuals, perennials, and subshrubs is found in the northern temperate regions and the mountains of the tropics. Members of the crassula family (Crassulaceae), species differ greatly in foliage and form. Some are shrubby, with flattened, oval, gray-green leaves, others trail and have succulent, rounded, "jelly bean"leaves, and some form very compact mats. Most produce small heads of tiny, 5-petalled, bright yellow flowers is summer and autumn. The genus name dates from Roman times and was used for several succulent plants. It is derived from the Latin sedo (to sit), referring to their low spreading habit. Some species have been used medicinally and as salad vegetables.


CULTIVATION


Plant in full sun with gritty well-drained soil. Most Sedum species appreciate water at flowering time but are otherwise drought tolerant. Propagate by division, from cuttings, or from seed, depending on the growth type.


Top Tip


The partnership of plump fleshy leaves and dainty starry flowers seen in Sedum species can be used to great effect in the garden to add textural and tonal contrasts.

SCHIZANTHUS

This Chilean genus of  12 species of annuals and biennials is in the potato family (Solanaceae), though that relationship is not obvious. The culivated species are small upright plants with soft green ferny foliage, often with a covering of fine hairs. Their flowers, which appear from spring to autumn, are borne in branching panicles held above the foliage. They are beautifully marked and shaped, with a prominent lower lip, hence the common name of poor man's orchid. Modern strains are available in a wide range of colors and sizes. The genus name comes from the Greek schizo (divide) and anthos (a flower), referring to the deeply divided corolla.


CULTIVATION


Schizanthus plants are tender, but easily grown as annuals where the summer temperatures are warm and even. Elsewhere treat as greenhouse pot plants. Plant in a bright position with fertile, moist, well-drained soil. Raise from seed, with several sowings to ensure containued flowering. Pinch out the growing tips when young to encourage bushiness.


Top Tip


Schizanthus plants are a bit fragile, but are worth the time spent providing care and protection. They don't like heavy rain or temperature extremes.

SCABIOSA

An unpleasant sounding name, Scabiosa is derived from scabies, a Latin word for scurf or manage, the itchiness of which was said to be relieved by running the affected are with the leaves of these plants. The genus, a member of the teasel family (Dipsacaceae), is composed of around 80 species of annuals and perennials found from Europe and North Africa to Japan. Most species form a spreading basal clump of light green to gray-green, rounded to lance-shaped leaves, with deeply incised notches or lobes. A few species have an erect or branching habit. The flowers are individually tiny but occur in rounded to flattened composite heads on stems that hold them clear of the foliage. White, pale yellow, soft pink, blue, and mauve are the usual colors.


CULTIVATION


The plants are hardy and easily grown in any sunny position with moderately fertile, moist, free-daining, slightly alkaline soil. Deadhead to prolong flowering. The annuals are raised from seed, and the perennials can be propagated from seed, from basal cuttings, or by division.


Top Tip


To attract butterflies and bees to the garden, Scabiosa species can be planted in borders and rock garden. The long-flowering species make good container plants.

SAPONARIA

This genus belongs to the carnation family (Caryophyllaceae), and features around 20 species of Eurasian annuals and perennials containing saponin, a glucoside that forms a soapy solution when mixed with water. The roots in particular were once used as soap, and the extract is present in detergents and foaming agents-hence the common name of soapwort. That use aside, these are pretty little plants that are well worth growing for their beauty alone. They are mainly low growing and range from tufted mounds to quite wide-spreading ground covers. They have blue-green linear to spatula-shaped leaves, sometimes toothed, and in summer are smothered in heads of small, starry, 5-petalled flowers.


CULTIVATION


Minly very hardy and easily grown, they do best in gritty, moist, humus-rich, free-draining soil. They will also take slightly alkaline soil. Propagate by cuttings, from layers, or from seed.


Top Tip


Mking a soft carpet of slarry flowers, Saponaria species are most at home spilling over banks, in rockeries, or placed in sunny perennial borders.

SALVIA

Containing about 900 species of annuals, perennials, and softwooded evergreen shrubs, this genus is the largest in the mint family. They are found in temperate and sub-tropical regions throughout the world, with the exception of Australasia, and grow in a wide range of habitats, from coastal to alpine. A number of Salvia species are used for culinary and medicinal purposes, and the genus name is derived from the Latin salvare, meaning to heal or save. Most species are hairy to some extent and many have foliage that is aromatic when crushed or rubbed. The flowers are tubular with the petals split into 2 lips, which may be straight or flaring. The flowers vary greatly in size, and the color range move through shades of blue to purple, and pink to red, as well as white and some yellows.


CULTIVATION


Most are best grown in full sun and all require a well-drained situation; generally, the shrubby plants dislike heavy wet soils. Propagation of most shrubby species is very easy from soft-wood cuttings taken throughout the growing season. Seed of all species is sown in spring.


Top Tip


While many Salvia or sage plants are tolerant of considerable dryness, most benefit from an occassional deep watering.

RUDBECKIA

This North American genus belonging to the daisy family (Asteraceae) consists of 15 species of perennials. It is very popular in gardens because of the plant's great hardiness, ease of cultivation, and valuable late season flowering. Most are fairly bulky plants, with branched or unbranched stems, and often have lance-shaped deeply veined leaves. From late summer they carry masses of large golden yellow daisies, usually with dark brown to black disc florets. Dwarf, double-flowered, and variously colored forms are available. They flower until cut back by frost. Rudbeckia was named by Linnaeus for a professor at the University of Uppsala, Olaus Rudbeck (1650-1740), who employed the young Linnaeus as  a tutor for his children, of which he had 24!


CULTIVATION


Plant in a sunny open position with moist well-drained soil. Deadhead or use as a cut flower to encourage continued blooming. Mildew can occur but usually only late in the season. Propagate by division, from basal cuttings, or from seed.


Top Tip


Because Rudbeckia plants bloom late in summer, they bring welcome color to borders and beds when the blooms of other plants have faded. 

ROSMARINUS

This genus is part of the large mint family, which includes many familar culinary and medicinal herbs. Rosemary itself has been cultivated for centuries, being grown fro the aromatic oil distilled from the shoots and leaves, and for use as a culinary herb. The genus contains just 2 species of evergreen shrubs from the Mediterranean region, and includes up-right and prostrate varities. They have short linear leaves and their small 2-lipped flowers are usually pale blue and borne along the branches, which can become quite woody with age. Apart from its culinary uses, rose-mary has been credited with many properties throughout its long cultivation: in ancient Greece, students wore sprigs of fresh rosemary in their hair believing the invigorating aroma would serve as an aid to mental clarity. This benefit has also been recognized by modern-day pracitioners of aromatherapy.


CULTIVATION


Rosemary likes a hot dry position and will grow in all sorts of well-drained soils; it will not tolerate wet winter conditions. It should be pruned after flowering to maintain a bushy compact habit, and is suitable for use as a hedging plant. Propagation is usually from softwood or half-hardened cuttings taken in summer.


Top Tip


Rosemary is an ideal plant for a mixed border, a hedge, or against a sunny wall. The flowers are edible, as well as decorative, and can be used in salads.

ROSA

The gens Rosa is one of the most widely grown and best loved of all plant genera around the world. Since ancient times roses have been valued for their beauty and fragrance as well as for their medicinal, culinary, and cosmetic properties. There are between 100 and 150 species of rose, which range in habit from erect and arching shrubs to scramblers and climbers. The majority of species are deciduous and most have prickles or bristles. They are found in temperate and subtropical zones of the Northern Hemisphere. The leaves are usually comprised of 5 to 9 serrated-edged leaftlets. Flowers, borne singly or in clusters, range from single, usually 5-petalled blooms to those with many closely packed petals. Many are intensely fragrant. Most species and old garden roses flower only once a year but many of the modern cultivars are repeat blooming. Rose fruits (hips or heps) are usually orangey red, but can be dark, lowa and North Dakota have Rosa arkansana as their floral emblem, while R.laevigata is the state flower of Georgia.


CULTIVATION


Roses can be grown in formal and informal settings, in separate beds, or mixed borders, as ground covers, climbing up arches and pergolas, as hedging, and in containers. Most roses require a sunny site and well-drained medium-loamy soil. Roses should be pruned to maintain strong healthy growth and a good shape. Except for the old Tea roses, most roses are very hardy. Propagation is from hardwood cuttings in autumn or softwood cuttings in summer.


Top Tip


When growing roses in containers, place a layer of stones in the pot, use a soil-based potting mix, and be mindful of the growth habit when selecting the pot.

RHODODENDRON

This very diverse genus of 800 or more species is widely distributed across the Northern Hemisphere, with the majority growing in temperate to cool regions. They range from tiny ground-hugging plants to small trees and even epiphytes, which grow in the branches of trees or on rock faces. Foliage comes in great diversity of form, and most rhododendrons bear "trusses" of up to 24 spectacular blooms, in colors ranging from white to pink, red, yellow, and mauive. Flowers are often multicolored, with spots, stripes, edging, or a single blotch of a different color in the throat of the flower. With the exception of some Vireya species and hybrids, fragrant rhododendrons are always white very pale pink. Blooms vary in sizes and shape but are generally bell-shaped, appearing from early spring to early summer. The fruit is a many-seeded capsule, normally woody wings or taillike appendages to aid transportation. Rhododendron macrophyllum is the state flower of Washington while West Virgina claims Rhododendroa maximum as its state flower.


CULTIVATION


All rhododendrons prefer acidic soils, high organic matter and freely draining. While most prefer some protection from wind, sun, and most many others tolerate these conditions. Evergreen rhododendrons may be propagated by taking up cuttings of the new growth in spring; deciduous azaleas are best grown from hardwood cuttings taken in winter.


Top Tip


Mulching is important for successful rhododendrons. In warm areas, mulch keeps soil cool; in cold areas, mulch helps the soil retain some warmth. 

RANUNCULUS

The type genus for its family, the Ranunculaceae, this is a widespread group encompassing some 400      species of annuals, biennials, and perennials, many of which are cultivated, while others are admired in the wild, and some are despised as invasive weeds. The foliage varies markedly, though glossy, leathery, kidney shaped leaves and deeply lobed leaves predominate. The flowers, too, are often glossy and they are borne singly or in small clusters through spring and summer. Most species have yellow flowers but cultivated forms occur in many colors, such as white, pink, and orange. Raunculus is Latin for little frog, a name given by the Roman Pliny because of the wet conditions in which these plants are often found.

CULTIVATION

Commonly known as buttercups, these plants are very hardy and will grow in a wide range of conditions but they prefer to have their roots kept cool and moist. Many species have trong rhizome that can be invasive if care is not taken to ensure that they are planted where they can be controlled. Propagate by division or from seed. Mildew can be a problem in autumn.

Top Tip

Adaptable to most conditions and soil types, buttercups will bring sunny colors to border or pond edges.

PULSATILLA

This genus of about 30 Eurasian and North American deciduous perennials (family Ranunculaceae) forms clumps of ferny leaves, which in most species are made silver by a dense covering of fine hairs. Long-stemmed cup- or bell-shaped flowers are carried singly with 5 to 8 petals and a prominent golden cluster of stamens. The flowers are graceful and occur in shades of white and yellow to violet-blue. The common name of pasque flower is from the old French word Pasque, meaning Easter, which is around the time when the plants flower in the Northern Hemisphere. Pulsatilla hirsutissima is the state flower of South Dakota.


CULTIVATION


Pulsatilla plants flowers are hardy and need a seasonal temperate climate. They grow well in woodland conditions but are at their best with sun or part-shade and gritty, humus-rich, well-drained by moist soil, such as that found in rocky crevices. Propagate by division when dormant or from seed.


Top Tip


Gardeners with sensitive skin should wear gloves when handling Pulsatilla plants, as both the leaves and the flowers may irritate the skin.

PRUNUS

Commonly known as cherry or cherry plum, Prunus includes both ornamental and fruiting species-cherries, plums, apricots, peaches, and nectarines-that are naturally widespread throughout the northern temperate regions and also have a toehold in South America. The genus also includes a wide range of shrubs and trees, many of them deciduous. Most bloom from late winter to early summer, producing flowers either singly or in clusters, in colors from white through to dark pink, followed by fleshy single-seeded fruit. The leaves are usually simple pointed ellipses, often with serrated edges, which sometimes develop brilliant autumn colors. Prunus persica is the state flower of Delaware.


CULTIVATION


Plant in moist, fertile, humus-rich, and well-drained soil in full sun. Provide some protection from strong wind. Propagate the fruiting plants by grafting, and the ornamental plants by grafts or in some cases by cuttings.


Top Tip


Correct pruning techniques are vital for fruiting varieties of Prunus, but less so for ornamentals, if silverleaf disease is present, cut back in summer rather than in winter.

PRIMULA

This well-known genus of perennials is native to the Northern Hemisphere. The heavily veined, toothed, or scalloped-edged leaves are pale to dark green and form basal rosettes. Single blooms may be tucked in among the leaves or borne in clusters throughout spring. The tubular flowers open out into a funnel shape or flat disc; are made upt of 5 or more petals, which are notched at their tips; and come in a variety of colors ranging from white, yellow, and pink to lilac and purple. Primulas are known variously as primrose, polyanthus, and cowslip, and some have been used medicinally for their astringent and mildly sedative properties.


CULTIVATION


Most species prefer the dappled shade of a woodland garden and like moit, humus-rich, well-drained soil. The so-called bog primroses prefer damper conditions and often naturalize along streamsides. Propagate from seed or by dividing established clumps when dormant.


Top Tip


Primulas can bring a burst of life to the garden. Easy to grow and readily available, they come in a wide array of different colors.