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Designing A Drought-Resistant Garden

By By Sereba Agiobu-Kemmer
07 May 2010   |   10:00 pm
MUCH of Nigeria has been in the grip of a rather long dry spell and the scarcity of water in many areas is playing havoc with our gardens and not all plants are up to the challenge. By using drought-tolerant plants, we can really reduce the amount of precious water that we use. Plants have…
MUCH of Nigeria has been in the grip of a rather long dry spell and the scarcity of water in many areas is playing havoc with our gardens and not all plants are up to the challenge. By using drought-tolerant plants, we can really reduce the amount of precious water that we use. Plants have developed to survive some of the most hostile environments on earth, and dry gardens don’t have to be dull or boring. There is an amazing selection of plants that have adapted in nature to not just survive, but also to thrive in the driest conditions.

There are many beautiful plants and flowers that are drought-tolerant, well-suited to our hot climate. Some are native plants, some come from other parts of Africa especially South Africa, the Americas, and the Mediterranean. So why do some plants cope better in dry spells than others? What does the term ‘drought-tolerant plants’ mean?

The term drought-tolerant plants means different things to different gardeners. There was a gardener who believed if a plant was considered to be drought-tolerant, it meant that once you planted it, you could then walk away and never have to water it again. The funny thing about it, in some respects, this can be true with some drought-tolerant plants, in some situations. Drought-tolerant plants have developed some extraordinary mechanisms for withstanding or avoiding dehydration: thick, fleshy, water-storing leaves; hairy or reflective foliage and small leaves which reduce the surface area through which water can be lost.

If you want to give your plants a better and even chance of surviving, water them during their first season. After that, they should be able to survive just from the water that falls from the sky. This, to me, is what the term drought-tolerant plants means. It means plants that have evolved in their natural environment to withstand long periods without rainfall and as a consequence, can do the same when introduced into a garden situation.

Group together plants with similar watering requirements.Think carefully about how your garden is designed and try to ground plants and flowers with similar water needs together. In that way, all the plants will get the amount of water they actually require. If you are lucky enough to have water for the garden, then good watering practices are essential to ensure that the water that you are applying is getting to your plants. Rather than a light sprinkle daily, give a good soak once or twice a week. This encourages the roots to grow deeper into the soil to further improve their drought tolerance. Try to water only the roots of the plants and not the foliage to prevent any precious water flowing away and any loss through evaporation.

Use water-saving crystals and mulch. Mulching is one of the best ways to conserve water in the garden, making sure that the layer is not too thick; 5-7 cm is adequate as water can be prevented from getting into the soil. Use water-saving crystals and mulch to retain water in the soil and reduce evaporation.

Water-saving crystals absorb water and provide moisture around the plant roots, while a good layer of mulch can reduce evaporation from the soil surface by as much as 70 per cent.

There are also some good water-saving products. Dripper watering systems are the most efficient way to water your garden. Drip irrigation provides water to plants where they need it most: at the roots.

Take a good look at the garden around your area to see how well plants are surviving through the driest weather, and take note of those plants that are thriving in the blistering heat with little water. Succulent plants also known as succulents or fat plants, are water-retaining plants adapted to arid climates or soil conditions. Succulent plants store water in their leaves, stems and/or roots. Geophytes that survive unfavourable periods by dying back to underground storage organs (tuberous roots, corms, bulbs, and rhizomes) can be regarded as succulents. Some plants are succulent geophytes.

Geophytic plants are plants that propagate by means of buds below the soil surface. The storage of water often gives succulent plants a more swollen or fleshy appearance than other plants, also known as succulence. In addition to succulence, succulent plants variously have other water saving features. These may include:

* Crassulacean acid metabolism (CAM) to minimise water loss;

* Absent, reduced, or cylindrical to spherical leaves;

* Reduction in the number of stomata;

* Stems, rather than leaves as main site of photosynthesis;

* A compact, reduced cushion-like columnar or spherical growth form;

* Ribs enabling rapid increase in plant volume and decreasing surface area exposed to the sun;

* A waxy, hairy or spiny outer surface to create a humid microhabitat around the plant which reduces air movement near the surface of the plant, thereby reducing water loss;

* Roots near the surface of the soil, so they are able to take up moisture from small showers or even from heaven dew;

* Ability to remain plump and full of water even with high internal temperatures (e.g. (52 celsius);

* A very impervious outer cuticle (skin);

* They contain mucilaginous substances which retain water strongly.

Many succulents come from the dry areas of the tropics, substropic, such as steppes, semi-deserts and deserts. High temperatures and low precipitation force plants to collect and store water in order to survive long dry periods. Succulents also occur as epiphytes. As such, they have limited or no contact with the ground, and are dependent on their ability to store water. Succulents also occur as inhabitants of sea coasts or salt pans which are exposed to high levels of dissolved minerals.

The best known succulents are cacti (family: cactaceac). Virtually all cacti are succulent, but not all succulents are cacti. Some of other plants families and general in which succulents occur include: Agavacae: Agave, yucca, Aizoaceac: Azizoanthenum,

Galenia, sesuvium, Tetragome

Subfamily mesembryan themoiideae

Amaryllidaceae Cgeopphytes, Lactaceae, Crassulaceae, Apolynaceae, Ridiereaceae, Euphorbiaceae, Asphodelaceae and Portulucaceae.

There are countless varieties of drought tolerant plants to select for the garden. For some families of plant, most members are succulent, for example the cactaceae, Agavaceae, Aizoaceae and Crassulaceae,

Agavaceae, Agave and Yucca.

Many people rightly think of agave and yucca as tough plants associated with extreme climates like deserts and dunes. What they may not know is that agave (Agave Spp.) and yucca (yucca spp.) also adapt well to home and commercial landscapes where they thrive in the sometimes harsh conditions associated with urban environments.

Agave and yucca are found in natural environments that typically are dry, hot, sunny and windy with low rainfall and poor soil. In cultivation, this adaptability translates into low maintenance since typically they need little or no irrigation, fertiliser, pruning, or spraying. Furthermore, many agave and yucca withstand drought, heat, strong winds and cold weather, and have few pests and diseases. They are tolerant of poor soils and therefore rarely develop nutrient deficiencies. The wide variety of sizes, shapes and growth characteristics permits many landscape uses including groundcover, bedding plants container plants, shrubs and especially dramatic specimen plants.

Above and beyond their toughness, agave and yucca capture the imagination because of their dramatic architectural forms and unusual shapes.