Cactus

...this group are the Christmas cactus (Schlumnergera bridgesii), Rhipsalidopsis gaertneri, and Rhipsalidopsis rosea. Some of the loveliest are the magnificent hybrids created by crossing Epiphyllum species with those of Echinopsis, Heliocereus, Hylocereus, and Nopalxochia. These hybrids produce extraordinarily beautiful, and sometimes fragrant, flowers in spring and summer, in colours ranging from pure white, through cream, yellow, and orange to red ...
...AND CONSERVATORY
Plants in a greenhouse or conservatory may be grown in pots or open beds, either at floor level or raised on benches. Planting in open beds offers potential for growing larger species and even for creating a miniature desert garden.

When in growth, many species from warm habitats need bright light, a fairly dry atmosphere, and a temperature of 18 degrees celsius (64 degrees fahrenheit) if they are to develop ... more

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CACTI AND OTHER SUCCULENTS
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Cacti and other succulents display a unique variety of sizes and shapes, and have a wealth of colour and texture. Some have plump, smooth surfaces, while others have curved or straight, sometimes colourful spines of a covering of silky hair. Their forms range from the symmetrical rosettes of Echeveria to the squat, globular Echinocactus and the fluted columns and candelabra of some desert cacti. Many bloom only briefly and bear large, brightly coloured flowers, while others flower for longer periods, producing a profusion of exquisite blooms. In cool-temperate climates, most cacti and other succulents are grown in the greenhouse or as house plants, but the hardier species also make beautiful garden displays. In warmer climates, there is scope to create an outdoor desert garden. Whether grown as single specimens or grouped for contrast of form and texture, the diversity of cacti and other succulents, and their tolerance of dry conditions, make them ideal for containers, both indoors and out.

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DESIGNING WITH CACTI AND OTHER SUCCULENTS
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Many cacti are native to the desert regions of the southern USA and Mexico, where rainfall is low and intermittent, and there are great extremes of temperature. In contrast, some of the most floriferous cacti originate in the warm, humid rainforests of Central and South America. These plants are usually epiphytic, which means that they grow on other plants, either weaving through host trees or lodging in niches in their branches.

Other succulent plants occur in a far greater range of habitats than cacti, and, since they are found in at least 20 different plant families, show a wide diversity of characteristics. Their natural habitats include the semi-arid regions of Central America, Africa, and Australasia, as well as the more temperate and cold climates of Asia, and northern parts of Europe and America.

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CHARACTERISTICS OF SUCCULENTS
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Cacti and other succulents show a number of adaptations, such as reduced leaf size and loss of leaves in very dry weather, that are designed to conserve water by reducing transpiration. The distinguishing feature that is common to all, however, is the presence of water-storing fleshy tissue in the stems, leaves, or roots. It is this tissue that allows succulent plants to withstand long periods of drought.

Cacti are easily distinguished from other succulents by structures called areoles - the cushion-like growths on their stems from which the spines, hairs, flowers, and shoots develop.

Succulent plants may be loosely divided into three groups, depending on which part of the plant contains the moisture-retentive tissue. Some genera, for example Euphorbia, may be represented in more than one group. Most cacti are stem succulents, as are some succulent plants from the Asclepiadaceae and Euphorbiaceae families. Others, including Aloe, Echeveria, Lithops, and sedum, are leafy succulents. Plants in the third group are known as caudiciform succulents and have the water-storing tissue in a swollen rootstock (the caudex), although this often extends into the stem, as in Adenium obesum. Plants that belong to this group are mostly found in the families Apocynaceae, Cucurbitaceae, and Convolvulaceae.

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FORM AND HABIT
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The diverse forms and growth characteristics of cacti and other succulent plants may be used to create a range of effects. The tall columns of Cleistocactus strausii, for example, make strong, vertical lines that contrast with foreground plantings of smaller, spherical forms, such as Echinocactus grusonii, or the characteristically flattened segments of some Opuntia species.

Several species have a creeping habit that adds a horizontal element to the design. Carpobrotus edulis, for instance, as well as Lampranthus and Ruschia species, make dense carpets of growth that provide excellent ground cover.

Trailing succulent plants, for example Ceropegia woodii and Schlumbergera and Rhipsalis species, produce cascades of slender stems or leaves that are seen to best effect in hanging baskets. A number are scrambling climbers: Aloe ciliaris and Selenicereus species add height to mixed plantings if given the support of trellis ot the branch of a tree. In warm, frost-free climates, the jointed and climbing stems of Hylocereus species are most effective when sprawling over walls.

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FLOWERING CACTI AND OTHER SUCCULENTS
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Cacti and other succulents often produce exquisite blooms and will flower regularly once they reach maturity, although this may take between one and 40 years. Most are day-blooming, with individual blossoms sometimes lasting for several days. Some epiphytic cacti are winter-flowering and have blooms that are carried in succession over long periods.

Others bloom only briefly, however, the flowers sometimes appearing soon after sunset and fading as evening advances. Many of the large, columnar cacti produce buds that gradually unfold during the evening and then fade in the early morning hours.

The flowers, often of delicate appearance and silken texture, are usually exceptionally large in comparison with the size of the plant, and their colour range is mainly at the warm end of the spectrum with a profusion of rich yellows, hot scarlets, and vivid carmines. A number of genera, often those of the family Mesembryanthemaceae, and some of the epiphytes, have sweetly scented blooms. Some species, especially members of the Agavaceae, are monocarpic, that is they die after flowering and setting seed. A number of small, non-flowering offsets are often formed around the flowering rosette, however, and these flower in subsequent years.

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OUTDOOR DISPLAY
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With careful selection and skilful arrangement, attractive collections of cacti and other succulents may be grown outdoors even in relatively cool conditions. Few succulents, however, tolerate excess moisture; even the hardy species require good drainage - these grow well in raised beds where water drains away freely. Among the hardiest are Opuntia humifusa, Sedum, and houseleeks (Sempervivum), along with some Crassula and Umbilicus species.

With shrap drainage and a good baking in summer, a number of desert cacti, particularly some Lampranthus and Opuntia species, withstand surprisingly low temperatures - although not the combination of cold and wet.

In mild areas that have few frosts, the range of plants is extended to include the spectacular rosettes of Agave americana and its cultivars, Agave filifera, and Beschorneria yuccoides. Half-hardy species need a freely draining site with the shelter of a warm, sunny wall for additional protection. Where temperatures are unlikely to fall below 7 - 10 degrees celsius (45 - 50 degrees fahrenheit), such as in the southern and south-western USA and the more southerly parts of Europe, there are few restrictions when choosing succulents for outdoors.

MIXED PLANTINGS
When growing non-succulent and succulent plants together, it is important to choose plants that have similar needs for light, soil type, and watering regime. In frost-free gardens, compatible non-succulents include Fuchsia, Nerium, Gazania, and Rehmannia species, all of which provide additional colour and variety. Bulbs and rhizomes such as Clivia, Cyrtanthus, and Sprekelia species are also good choices in mixed plantings.

In cooler regions, annual species and plants that are grown as annuals, such as Lampranthus species and Portulaca grandiflora, are suitable for planting outdoors among groups of perennial cacti and succulents.

DESERT GARDENS
In arid climates where temperatures seldom fall below 10 degrees celsius (50 degrees fahrenheit), the complete range of cacti and other succulents may be grown in a desert garden to create a fine landscape feature. Where the subsoil is particularly heavy, collections of plants may be grown in raised beds to ensure the excellent drainage that these plants require.

Use smaller species at the front of the bed, so that their delicate beauty is not obscured by taller plants. Allow clump-forming plants, such as Echeveriam Haworthia, and Mammillaria species, sufficient space to develop fully. These low-growing, cluster-forming species flower at different periods from spring to autumn, to give colour during the warmer months.

For background planting, erect, columnar cacti and other succulents are ideal. Choose plants such as the tall, single-stemmed Cephalocerous senilis, the branching Cleistocactus strausii, or the towering, tree-like form of Euphorbia candelabrum.

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CONTAINERS OUTDOORS
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Most cacti and succulents have shallow roots and respond well to being grown in containers. Select containers that enhance the shape and form of the plants - a wide, shallow bowl, for example, is the natural choice for displaying low-growing and creeping species, whereas those with stronger form, such as Agave attenuata, are much better suited to large pots or urns.

Troughs are particularly useful for creating imaginative combinations of plants of quite different sizes and habits, and hanging baskets are suitable for displaying trailing and pendent species.

CHOOSING AND SITING THE PLANTS
In cool regions, but where temperatures seldom fall below freezing, many species will thrive outdoors in troughs and pots, provided that these are raised above ground to allow water to drain away freely. A warm, sheltered position such as a corner of a covered patio or balcony, where the plants can more easily be protected from the rain, will provide the ideal environment.

The foliage shapes of Sedum and neat rosettes of Sempervivum may be used to form a contrast with the leafy forms and brilliant blooms of Lewisia species and cultivars, or with the green-flowered Echinocerous viridiflorus and the scarlet, early summer blooms of Lobivia silvestri. Other species, such as Agave parryi, which has symmetrical rosettes of plump, grey-green leaves, or Opuntia polyacantha, with its brilliant display of yellow flowers, make striking focal points if they are planted on their own in large bowls.

In warmer climates, there is much greater scope for growing cacti and other succulents outdoors in containers. In large pots, group plants that flower at different periods and have striking foliage forms: the purple-leaved Aeonium arboreum 'Schwarzkopf', Aloe barbadensis, which has yellow flowers, and the red-flowered Crassula falcata will provide structural interest all year round, and give a succession of attractive blooms throughout the warmer months.

Where temperatures do not consistently fall below 13 degrees celsius (55 degrees fahrenheit), many dwarf cacti, such as species of Gymnocalycium, Mammillaria, and Rebutia, make fascinating displays of form and texture in outdoor bowls and troughs in the garden. These dwarf, cluster-forming species also give a magnificent display of vibrant colour that will last for many weeks on end during the summer.

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INDOOR DISPLAY
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The protected environment of the greenhouse or conservatory, which allows almost complete control of light, temperature, humidity, and water, provides ideal conditions for an extensive range of cacti and other succulents - most of the plants recommended for outdoor cultivation in warm climates will thrive under cover in cooler regions. The adaptations these plants have made to help them to survive in harsh, arid environments in the wild also make them well suited to the warm, dry conditions of the centrally heated home, where many other plants may fail to thrive.

The variation in shape and habit, and their beautiful flowers, ensure that these plants provide interest throughout the year, and, since different species are adapted to a variety of environmental conditions, they may be selected to suit a number of situations in the home.

PROVIDING THE RIGHT CONDITIONS
The great majority of cacti and other succulents need high light levels, warmth, and good ventilation to thrive, although some, the leafy succulents in particular, may need protection from direct sun in summer to avoid leaf scorch.

There is an important group, however, that requires shady conditions, or at least filtered light: these are epiphytes that come from the humid and shaded rainforests of Central and South America.

Epiphytic plants are among the most floriferous of cacti and other succulents, and they can be used to great effect to add bold splashes of colour and interest to shady corners of the home or garden. The best known of this group are the Christmas cactus (Schlumnergera bridgesii), Rhipsalidopsis gaertneri, and Rhipsalidopsis rosea. Some of the loveliest are the magnificent hybrids created by crossing Epiphyllum species with those of Echinopsis, Heliocereus, Hylocereus, and Nopalxochia. These hybrids produce extraordinarily beautiful, and sometimes fragrant, flowers in spring and summer, in colours ranging from pure white, through cream, yellow, and orange to red and deepest purple.

PLANTS FOR THE GREENHOUSE AND CONSERVATORY
Plants in a greenhouse or conservatory may be grown in pots or open beds, either at floor level or raised on benches. Planting in open beds offers potential for growing larger species and even for creating a miniature desert garden.

When in growth, many species from warm habitats need bright light, a fairly dry atmosphere, and a temperature of 18 degrees celsius (64 degrees fahrenheit) if they are to develop to their full potential and bear flowers. These conditions are more easily provided under glass than in the home, and many cacti grow and flower most successfully in the greenhouse.

Some, notably Rhipsalis species, require fairly high levels of humidity (80 percent) to thrive, and nearly always perform best in the humid atmosphere of a conservatory. Other groups that are well suited to the conservatory and greenhouse are those that need space to grow and flower well. These include the clambering Selenicereus (the most outstanding species is Queen-of-the-night, Selenicereus grandiflorus) and several Hylocereus species, all preferring filtered light.

When drawing up planting plans for a greenhouse or conservatory, combine groups of cacti and other succulents that have similar cultural needs, to make maintenance easier.

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CONTAINER-GROWING INDOORS
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If provided with warm, bright, and draught free conditions, many cacti and other succulents will thrive in indoor containers. Use small pots for displaying individual plants, or large bowls for planting a variety of compatible species together.

Wear gloves when handling spiny plants such as Agave, Aloe, and Opuntia, because their sharp spines may easily become embedded in your fingers if you brush against them, causing a painful injury.

BOWL GARDENS
If planted with different species that have the smae cultural requirements, bowl gardens are particularly effective for growing succulent plants indoors. One or two plants with an erect habit, for example young specimens of Cephalocereus, Cleistocactus, or other columnar genera, may provide the focal point of the bowl. Alternatively, use a leafy succulent such as Crassula ovata as the main plant. Fill the rest of the bowl with smaller plants, such as Echeveria and Lithops. Free-flowering cacti such as Mammillaria, Notocactus, and other globular cacti are also good choices for planting in a bowl garden indoors.

HANGING BASKETS
Succulents in hanging baskets make colourful displays in the home or conservatory. Pendent cacti such as Aporocactus flagelliformis, and trailing succulent plants such as Kalanchoe, Rhipsalidopsis gaertneri, and Schlumbergera species and cultivars are the most suitable plants to choose, since they will trail attractively over the edge of the basket. Sedum morganianum and other semi-trailing species are also effective in hanging baskets.

Plant hanging baskets with just one specimen, or use several species for a harmonious but varied arrangement of shape and texture. In general, non-epiphytic plantings require bright light, but epiphytes need partly shaded conditions or bright but filtered light, so position the baskets accordingly.

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SOIL PREPARATION AND PLANTING
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Many cacti and other succulents grow naturally only in desert or jungle conditions, but they also make striking displays out of doors in cooler climates. Whether grown indoors or outside, specially prepared, well-drained soil or compost is essential. A sunny site with adequate protection from frost is also required for most species.

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BUYING CACTI AND OTHER SUCCULENTS
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When buying cacti and other succulents, choose healthy, unblemished plants that show new growth or have flowerbuds forming. So not buy damaged or slightly shrivelled specimens, or any with dull, dry, or flaccid segments. Also reject plants that have outgrown their pots.

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PLANTING IN A RAISED BED OR DESERT GARDEN
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Cacti and other succulents require well-drained conditions, so they benefit from being planted in a bed that is raised at least 25cm (10in) above ground level. To ensure good drainage make the bed slightly sloping and provide a thick base of gravel or crocks that is at least one third of the total height of the bed.

Never construct the bed on a concrete or other impermeable base as this impedes drainage. Choose a bright, sunny site with a minimum temperature of 5 degrees celsius (41 degrees fahrenheit). In cooler areas, provide adequate protection for tender species.

PREPARING THE SOIL AND COMPOST MIX
Cacti and other succulents do not usually thrive in ordinary garden soil, because it is not sufficiently well drained; it needs to be replaced by or supplemented with a carefully prepared growing medium. Good garden loam that has a pH level of 4 - 5.5 may be used as the basis of a home-made compost. It must be sterilized first, however, to kill bugs or weed seeds that might be present, and to eliminate diseases.

To prepare the compost, mix 2 parts sterilized garden loam with 1 part peat substitute or fine shredded sphagnum or sedge peat, 1 part sharp sand or washed grit, and a little slow-release fertilizer.

If the garden loam is alkaline, use a loam-based proprietary compost mixed with sharp sand or grit in a ratio of 1 part sand or grit to 3 parts compost.

PLACING PLANTS IN THE BED
Water the plant, and carefully remove it from its pot. Check the root ball for disease or bug infestation, and treat any infections before planting.

Dig a hole of appropriate size and place the plant so that its base is at the same level in the soil as it was in its container. Fill in around the roots with compost, and firm, making sure that the stems and leaves are above soil level. Top-dress with grit, to protect the plants from excess moisture and reduce soil water evaporation. Allow the plants to settle, then water, lightly at first, gradually increasing the amount until the plants are well established and producing new growth.

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SUCCULENTS IN CONTAINERS
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A collection of cacti and other succulents grown in pots, bowls, or troughs provides an attractive focal point on a patio or windowsill.

PREPARING THE COMPOST
The compost used should be well-drained and preferably slightly acid with a pH of 4 - 5.5. Use 1 part sand or grit to either 3 parts loam-based compost or 2 parts loamless compost.

A slightly more acid compost may be required for epiphytic succulents, such as Hoya species, and cacti - Rhipsalis and Schlumbergera in particular - native to forest areas. Mix 1 part humus (such as peat substitute, sphagnum peat, or leaf mould) with 2 parts standard potting compost; add sand or grit to ensure adequate drainage.

CHOOSING THE POT OR CONTAINER
Both clay and plastic containers are suitable for growing cacti and other succulents. Compost in plastic pots retains moisture longer than that in clay pots, which means that the plants need less frequent watering, but clay pots provide better aeration around the roots. Choose containers that have one or more drainage holes in the base to ensure that water drains away quickly. The size of pot or container should always be proportionate to the size of the plant but never less than 10cm (4in) deep; for tuberous-rooted species such as Wilcoxia species, a pot with a depth of at least 15cm (6in) is preferable.

PLANTING IN CONTAINERS
Always wash thoroughly all containers before use to remoce possible sources of infection. Place a layer of drainage material (washed gravel or broken crocks) in the base, to approximately one third of the depth of the container; large troughs as well as deep bell- or urn-shaped pots need at least an 8cm (3in) base of gravel or crocks to ensure sufficient sharp drainage. Fill the container with compost to within 1cm (1/2in) of the rim

Carefully remove the plant from its pot, discarding any top-dressing, and insert it into the new container so that the top of the root ball is at the same level in the compost as it was in the original pot. Firm the plant into the compost, and then top-dress with coarse gravel or with grit.

When planting several cacti or other succulents in one container, space the plants so that there is room for them to develop. To create a more natural effect, decorative pieces of rock or pebbles may be added to the composition.

Allow the plants to settle for a few days before watering; water routinely only when the plants are well established.

HANGING BASKETS
To create an attractive and slightly unusual feature, plant trailing succulent species in a hanging basket. Make sure the basket is completely clean. Wire baskets should be lined with a proprietary liner or a layer of sphagnum moss. Do not line the basket with plastic sheeting, since this restricts drainage. If using a plastic that has a fixed drainage tray, place a layer of small pebbles or gravel in the base instead of sphagnum moss.

Fill the basket with an appropriate potting compost, without disturbing the moss or pebbles, then insert the plants in the same way as for other containers. Do not overcrowd the basket, as most suitable species have a naturally spreading or pendent habit; one plante is often sufficient to fill an average-sized basket. Top-dress with gravel or grit if extra drainage is required; allow to settle for a few days before watering. Once the plant is established and showing new growth, routine watering may be applied.

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ROUTINE CARE
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Cacti and other succulents need little maintenance in order to thrive, but they must have adequate light, warmth, and ventilation. Feed and water as appropriate for the particular species, and check regularly for signs of diseases or bugs. Repot plants in containers as soon as they outgrow them, to prevent them from becoming pot-bound.

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THE RIGHT ENVIRONMENT
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Place cacti and other succulents in a position appropriate to their cultural needs. Most species need full sun, although some prefer dappled shade. The maximum daytime temperature in spring and summer should be 27 - 30 degrees celsius (81 - 86 degrees fahrenheit), and the night-time temperature 13 - 19 degrees celsius (55 - 66 degrees fahrenheit). During the dormant season, most plants should be kept at a temperature of at least 7 - 10 degrees celsius (45 - 50 degrees fahrenheit), although species from the tropics and equatorial regions may require a warmer environment, with a minimum temperature range of 13 - 19 degrees celsius (55 - 66 degrees fahrenheit).

VENTILATION
Good ventilation is essential, although cacti and other succulents should not be exposed to draughts. For plants grown in a greenhouse it may become necessary to use blinds or to apply proprietary shading paint to the outside of the glass, if ventilation is insufficient to keep the temperature below 27 - 30 degrees celsius (81 - 86 degrees fahrenheit). In exceptionally hot weather, watering the greenhouse floor will help to reduce the temperature. Occasionally, plants grown in the open may need some shade to protect them in conditions of extreme heat.

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WATERING AND FEEDING
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Water only when the plants are in active growth (not during their resting period). For most cacti and other succulents this is in summer, but epiphytes and succulents from forested areas bloom principally between late autumn and early spring. In the dormant season, do not water unless temperatures remain high, and then only enough to prevent complete dehydration.

WATERING
During the growth season, moisten the soil or compost thoroughly with tepid water, allowing it almost to dry out before watering again. Provided that the plants are grown in free-draining soil, surplus moisture drains away quickly.

Water early in the day or in the late evening, as the plants may scorch if they are covered in water droplets in bright sunshine. Alternatively, plants that are grown in pots may be watered by placing the container in a shallow pan of water, so that the water permeates the compost, but does not touch the stems or leaves. Remove the container from the water to drain as soon as the surface of the compost appears moist; the plants will rot if left standing in water.

Epiphytic plants and those that need shaded conditions should be kept moist but not wet: an occasional, light mist-spray maintains a reasonable level of humidity.

FEEDING
During the growing season, feed cacti and other succulents to help maintain healthy, vigorous growth and to encourage flowering. Several proprietary fertilizers are available but a standard, well-balanced liquid fertilizer containing all the major nutrients is satisfactory. Apply in accordance with the manufacturer's instructions at four-weekly intervals. Never apply fertilizer when the plant is dormant or the soil is dry as this may damage the stems and foliage.

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HYGIENE
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Cacti and other succulents may need occasional cleaning, as dust sometimes accumulates on the leaves or between the spines. During the growing season, house plants may be sprayed lightly with water; succulents in the greenhouse or garden may be hosed down carefully, provided that they are not in direct sun.

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BUGS AND DISEASES
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Check cacti and other succulents routinely for bugs and diseases. The most prevalent bugs are mealybugs, scale insects, red spider mites, root mealybugs, and sciarid flies.

Diseases of cacti and other succulents are rare, although poor cultural conditions or excess nitrogen in the soil may encourage the development of black rot, which principally affects epiphytic cacti and Stapelia species. The plants become disfigured and may die. There is no treatment, so, if it appears that a plant is likely to die as a result of infection, take healthy shoots or sections as cuttings and grow them on to replace the diseased plant.

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REPOTTING
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Cacti and other succulents should be repotted as soon as the roots begin to show through the drainage holes - usually every two to three years for fast-growing species. Repot slow-growing plants every three to four years. Always water a plant before repotting so the roots do not dry out.

Carefully remove the plant from its original pot. Inspect the roots, looking for signs of bugs or diseases, and treat if necessary. Cut out any roots that are dehydrated or dead, adn dust with fungicide. Choose a new container one sixe larger than the original, and repot, ensuring the planting depth is the same. 

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