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Container Plants that Beat the Heat

There are a number of tough waterwise characters that thrive in containers and love being out in the midday sun. Summer can take its toll on container plants and having continually to replace ones that succumb to the heat every year is tiresome and expensive.

There are, however, some hardy perennials that grow easily and enjoy our summers. They all have good structure with most producing showy blooms at different times of the year. They require minimum care and are not plagued by pests and disease.

Bougainvilleas

Although Bougainvilleas are mainly used to form dense, impenetrable hedges or to cover pergolas, there are a few compact ramblers and even ground cover types that create explosions of colour in large containers. These plants demand full sun.

Bougainvillea ‘Tropical Rainbow’ with its cream and green variegated leaves looks good in a classic urn. The special quality of this rambler is its new growth, which is a reddish-pink colour with watermelon-red flower bracts.

Good to know

  • Water bougainvilleas in pots thoroughly and frequently in summer, but only when the soil is dry. Do not over water, as this will only encourage leaves and not flowers.
  • Feed potted bougainvilleas regularly in summer with liquid fertiliser.
  • Prune them occasionally to retain a neat shape.
  • They are best for subtropical and temperate gardens as they are sensitive to frost and cold.

Echeverias

Echeverias have become very popular container and garden plants, possibly owing to their very structured appearance, water-wise qualities and low maintenance. There are many hybrids available on the market and once the collecting bug has bitten you, you will want them all! Echeverias tolerate light shade as well as full sun. Plants in small containers must, however, be watered regularly.

Echeveria agavoides presents as a single rosette without a stem. It can grow quite big before plantlets start growing around its base, eventually forming dense clumps. The leaves are smooth, sharply pointed and bright green with blood red edges. This species can endure more cold and drought than most echeverias.

Good to know

  • Echeverias prefer soil with good drainage and aeration.
  • Although they are fairly drought tolerant, they will appreciate being watered when the soil dries out as long as there is good drainage.
  • Most echeverias can be propagated via their leaves which, once detached from the main plant, should start to grow roots.
  • E. agavoides do not propagate this way, they will produce offsets that can be divided from the mother rosette.

Aloe ‘Hedgehog’

The dwarf Aloe ‘Hedgehog’ only grows to about 40cm high, but it looks great in any sized container. ‘Hedgehog’ is a hybrid of indigenous Aloe species, bred by a local plant breeder. The grey-green leaves are thorny, narrow and arranged in a tight rosette causing them to form a compact, but spiky, ball. It grows fast and forms numerous offsets (plantlets) resulting in a thick clump. During autumn and winter numerous flower spikes with nectar-rich tubular coral-orange flowers appear.

Good to know

  • They are disease-resistant.
  • They are suitable for all but the frostiest of climates. Protect pots from extreme winter cold.

Cotyledon orbiculata (Pig’s Ear)

Leaf-colour and shape varies tremendously with the very worthwhile indigenous Cotyledon orbiculata. Amongst the different forms and varieties, you will find luscious emerald-green to grey specimens often with a red line around the margins of the large, fleshy leaves.

The white-leaved form with its pale margins is very desirable as a garden ground cover, or for containers. The growth habit is so structural and pretty that one doesn’t necessarily need the clusters of bell-like flowers they produce in winter and, in some cases, a second flowering in summer. The colour of the flowers may vary greatly, ranging from yellow to orange and pink to red.

Good to know

Although cotyledons will grow virtually anywhere, heavy frost and cold can damage the plants so it’s best to protect your pots against frost in winter.

Agaves

Agaves hail mainly from Mexico and tropical America. Their genus is diverse when it comes to shape, foliage, colour and texture, but these tough plants all have rosettes of thick, heavy leaves. Some, like Agave attenuata and Agave geminiflora, are popular accent plants and have become common inhabitants of garden containers. But there are other desirables too.

Agave parryi var. parryi is a squat succulent that is ideal for collectors who love container gardens filled with interesting succulents. It is slow-growing, but is a lovely dwarf agave with grey-green to steel-blue, broad fleshy leaves that end in sharp black thorns. This plant is extremely waterwise and fairly hardy, but in very cold areas it should be protected in winter. A parryi var. parryi is not always available, but is well worth the search.

Sedums

Sedums range from annuals, creeping herbs and ground covers, to shrubs. It is a large genus which has one very important common characteristic – the water-storing capabilities of its leaves. Most Sedums thrive in pots.

Sedum nussbaumerianum is an exotic species from Mexico, with unusual, copper-coloured rosettes on slender spreading stems. It is a lovely plant on its own or mixed with other sun lovers in a pot. Small star-shaped white flowers with a soft fragrance are produced in late winter to spring. The plant can easily by propagated by leaf or stem cuttings and is well worth planting as a groundcover in sunny rock gardens.

Good to know

  • If you are looking for a tough plant to fill hanging baskets, then use this sedum.
  • They grow in partial shade or full sun.

Hot Tips

Attractive containers holding one specimen plant, or a good combination of complementary plants, make strong focal points and should be displayed to their best advantage:

  • Group more than one pot of the same design together.
  • Pots in pairs or rows, planted up with the same plants, make a dramatic impact.
  • Ordinary terracotta clay pots, 30cm x 27cm, look great if placed along steps or on the ledge of a wall, fountain or raised water feature. They are also big enough to allow lush growth for succulents like Echeverias or small Aloes.
  • You can plant a small, compact plant with a shallow root system – like a dwarf Aloe – in tall, narrow pots. To save on potting soil, place a few rocks in the bottom of the pot, add a layer of broken polystyrene pieces, other packaging material or empty plastic bottles and only fill the top half with potting soil.

Planting Basics

  • Make sure all containers have wide-open drainage holes or you can lose plants as a result of rotting in water-logged soil.
  • Clean all used pots with a disinfectant to prevent the transfer of root diseases to new specimens.
  • Never use ordinary garden soil. Buy good quality potting soil for non-succulent plants like bougainvilleas and a commercial succulent medium for aloes and other succulents. Add some bone meal to the potting soil to encourage strong root systems.
  • Remember that the soil for container plants will gradually be leached of minerals and nutrients and even the toughest plants need to be fed occasionally. Mulching all containers with a fresh layer of compost and feeding the plants regularly in summer with a water-soluble fertiliser can do no harm.

Source: Gardening with Succulents, by Prof. Gideon Smith, Struik Publishers, 2005. ISBN 1 77007 082 6.

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