THE summer equinox may be long past, but the sun is still high in the sky. And long days mean loads of sunshine and heat to stimulate maximum growth in plants.
February in Cape Town is also notoriously dry – and establishing a garden often needs water.
When nature is not providing any of that, it is up to gardeners to make sure that plants have what they need to thrive.
There are fortunately many methods you can employ to conserve water in the soil, where it is available for use by your plants, instead of being lost to evaporation during the heat of summer.
Employing the following techniques will also help reduce your water bill considerably – and also transform you into an eco-conscious, water-aware citizen.
Retain moisture in the soil
There are three infallible methods to prevent moisture loss from the soil, and to retain that moisture around plant roots for longer.
A humus-rich soil – one that is light and friable and rich in organic matter – holds water better than a sandy or a clay soil. In addition, it provides good nutrition for plants.
To achieve this desirable soil type, add masses of compost – or partially decomposed compost – to all soil types, but especially to clay and sandy soils.
At this time of the year it can be applied as a mulch, rather than digging it in, which in turn loses soil moisture to evaporation.
Earthworms and other organisms will carry it downwards into the soil.
A properly-mulched garden can save between 50 and 70 percent of water, as it helps prevent evaporation. In summer put down a 10cm thick layer of mulch on all your borders, and on top of the soil in containers. The ideal mulch is light and permeable enough to allow water and air to pass through, yet dense enough to inhibit or eliminate the growth of weeds.
Mulches may be organic (usually plant material) or inorganic (crushed stone or gravel).
Any biodegradable material can be used as organic mulch. Examples are shredded or chipped bark, pine bark nuggets, shredded leaves, grass clippings, pine needles, straw, peanut shells, peach pips or partially decomposed compost. Organic mulches contain nutrients that gradually wash down into the soil and fertilise the plant roots. For this reason they are more beneficial than inorganic mulches in respect of improving soil quality.
An added advantage of mulching is that weeding and hoeing the garden are practically eliminated. The few weeds that manage to poke up through the mulch are easily nipped out and, when organic mulch is used, there’s no need to cultivate because the mulch is slowly incorporated into the soil by earthworms, thus keeping the soil loose.
These swell up in volume when wet, forming a gel in which water is held. When these polymers are placed in planting holes or containers, they ensure that water is retained around the roots of plants, instead of penetrating past the root zone, as is the case in sandy soils in particular. The holding action of the gel also slows down the natural evaporation rate.
Irrigate wisely, not wildly.
To reduce water usage and frequency of irrigation, avoid watering in the middle of the day when as much as 30 percent of the water used to irrigate gardens is lost to evaporation. Also, avoid watering during windy conditions when water is carried away from beds and borders.
Instead, water at night, when the ambient temperature is cooler, and the wind has died down.
Also be aware that different plant types have different irrigation needs. Taking these into account helps make garden irrigation highly efficient.
This will allow the water to soak in gradually, instead of running off elsewhere as soon as the surface is wet. Alternatively, get busy with a lawn spiker or aerator to enable water to penetrate into the soil and reach the roots of the grass.
Larger containers can last several days between waterings, but keep an eye on them too.
An alternative is to consider clustering several container plants together in a group during summer. This technique results in the plants partially shading each other, so retaining their soil moisture longer.