Principles of Water-wise Gardening

Water-wise gardening

Follow the natural rainfall patterns

 

Where do you live? Most of southern Africa falls into a summer rainfall zone with cold, dry winters while the Western Cape has a typical mediterranean climate with cool, wet winters and hot, dry summers. Use the local climate to your advantage by using indigenous plants that have adapted to your local rainfall. Also do most of the planting in the beginning of the rainy season so that the plants have time to establish themselves before the dry season. To find out more about plants suitable for your area, read the articles on Veld Gardening.

 

Provide shelter from the wind and sun

 

Create different areas in the garden to enjoy, by planting trees for shade and windbreaks for shelter.

 

Group plants according to their water needs

Plants have different water requirements. By planning your garden carefully, you can group plants according to their water needs and avoid wasting water on plants that do not need it. For example group the special plants with high water demands close to the house, entrance or living areas so that they are easy to water regularly and can be enjoyed daily. The plants with low water requirement usually also need less maintenance.

 

Improve the soil

Whatever the soil type (sand, clay or loam) the quality and water-holding capacity can be improved by adding compost. This encourages earthworm activity, which helps to improve the soil aeration and water penetration. Compost also enriches the soil with nutrients. This promotes the growth of healthy plants, which will require less water and be more disease-resistant than plants that are underfed. Before planting dig in large amounts of well-decomposed compost.

 

Much more mulch

Remember to spread a layer of mulch between the plants immediately after planting. By covering the soil with a thick layer of mulch the amount of water that evaporates is reduced, the soil kept cool, water run-off and soil erosion reduced, and the growth of weeds reduced. Different materials can be used as a mulch, such as compost, bark, leaves, wood chips, straw or pine needles. These organic mulches have the advantage that they add nutrient to the soil as they break down, but therefore have to be replaced regularly. Inorganic mulches like pebbles and stone chips are also effective.

 

Reduce your lawn

A lush green lawn during the dry months requires a lot of water regularly. First replace the lawn in areas where it is not growing well, such as shady areas or along footpaths. Then decide how much lawn space you need for outdoor entertaining, children and pets. Replace the excess lawn with hardy groundcovers, a water-wise flowerbed or interesting paving.

 

Water correctly

Most people over-water their gardens. Watering depends on your soil type, irrigation equipment, the weather and the type of plant. To determine the soil type, simply squeeze some damp soil in your hand and roll it into a sausage. Sandy soils will fall apart; loamy soil will hold together but crumble easily, and clay soil will mould into different shapes without breaking apart. With sandy soils, water drains quickly beyond the reach of the plant roots and these soil therefore require short, frequent watering. Clay soil has a high water-holding capacity, so it is best to give a deep watering, less often. Also remember the following:

  • Never water while the wind is blowing and only early in the morning or in the evening to reduce evaporation.
  • Group plant with similar requirement together and adjust watering according to their needs.
  • Do not water automatically, first check whether the soil is dry
  • With trees and shrubs, rather water copiously less often so that the roots are encouraged to grow deeper.

 

Grow water-wise plants

When choosing plants for your garden try to select from the indigenous plants from your area/biome. But you may also be tempted to try some plants from other parts of the world which have similar climates. In the Western Cape, many beautiful plants from other mediterranean areas such as rosemary, lavender, thyme, cyperus and myrtle grow well with a minimum of water. But always be careful to avoid exotic plants which have the potential to invade natural areas in South Africa like hakea, Port Jackson, lantana and black wattle.

There are many beautiful plants which are naturally drought resistant. To grow in dry conditions plants have developed a number of adaptations. They survive by storing water, reducing water loss through the leaves or by going underground during the dry season. When choosing plants for your garden, look for some of these features:

  • Succulent plants, such as aloes, store water in their thick stems, leaves or roots.
  • Plants like ericas have small or needle like leaves to minimise the surface area from which water is lost by evaporation.
  • Many bulbous plants like the March lily (Amaryllis belladonna) survive the dry season by going dormant and "ducking underground".
  • Annuals like the Namaqualand daisies (Dimorphotheca pluvialis) have adopted a similar strategy, by surviving in the form of seed.
  • Hairy leaves, a waxy leaf coating, or grey leaves also make it easier for plants to retain water and reduce heat.

 

Liesl van der Walt
Kirstenbosch
March 2001
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