So you find yourself in the middle of the worst drought within living memory and your garden occupants are starting to sag, flag and wilt. Which plants should be watered first and which plants should receive the main quantities of the irrigation? You begin to feel like the leader of a third world country trying to spread your counties meagre budget across healthcare, military and education. Never fear, let me dampen your worries with some drought advice.
First to receive the H2O
Recent plantings are top of the list for regular watering, if water is available. New plantings such as bare-root trees or shrubs planted the previous autumn / winter, with newly planted perennials also at great risk from drought damage. You see these new plantings have not had much time to produce water-seeking roots, the type of roots that travel deep and wide for moisture. Because of this, we must supplement the plants natural water supply. During a hosepipe ban, recent plantings of annual bedding summer bedding such as marigolds, impatiens, Nicotiana etc should be regarded as probable casualties of the water war. If I had a limited supply of water to divide between a Japanese maple and some annual bedding, I am afraid the maple would receive the lions share and to hell with the bedding. As a rule of thumb, if the soil 5cm (2 inches) below the grounds surface is dry, then it is time to water.
Container plants during a drought
Next on the water-receiving list are containerized plants, hanging baskets and window boxes. Essentially a containerized plant is growing above the ground water table, with just the soil inside the container to provide the required moisture. If the moisture is not inside the container, then I am afraid the roots have nowhere else to go to quench the plants thirst. Again, if the compost 5cm (2 inches) below the pots surface is dry, then it is time to water, it is up to the gardener to provide that water when required. Try to provide a catch plate or tray beneath containers, these “catchers” will contain any excess water that will eventually be absorbed in the compost. Be aware that terracotta and other porous container materials absorb a good quantity of water that the plant is then unable to access. The following is a short list of container bedding plants that can cope with a short period of drought, once established… Arctotis, Lantana, Plectranthus, Portulaca and Zinnia
Vegetables and fruit during a dry spell
Provide adequate quantities of water for moisture-hungry vegetables such a tomatoes, peas, onions, cucumbers, marrows and lettuce. Insufficient supplies of water will lead to miniature, shriveled and limp specimens. Fruiting plants such as strawberries, raspberries, currants, apple and pear trees are also very moisture hungry especially while their fruit is forming. Notice how much water is within a strawberry or pear the next time you eat one of these delights. Water-content figures of 70 to 90% are quoted for fruits and vegetables, regardless of whichever quantity is correct, you must supply that water during a drought. Plants growing in an exposed or wind swept area will require a fair quantity of supplementary water during a drought. Have you ever gone for a bracing walk on a windy day, upon arriving home, you smile at your spouse, children or pet and realize that your lips are cracked and chapped, ouch! This illustrates the severe drying element of a strong breeze, plants leaves are constantly being dried out and then remoistened by water from the soil when available. During a drought, if that water is not present the leaves will dry up, shrivel and shed. This is known as the desiccation of foliage. Watering deeply will prevent this happening.
Shallow rooters and moisture lovers
Shrubs and trees that are shallow rooted or have a particular liking for moist soils are quite at risk during a drought period. The shallow rooted specimens include Rhododendron, Azalea, Heather (Erica), Hydrangea and Birch (Betula). The moisture lovers include Hosta, Ferns, Helleborus, Sarcococca, Fatsia and Camellia. If water is available, please allocate some to these plants. Climbers or wall-shrubs planted close to house walls will struggle for moisture at the best of times, due mainly to the rain-shadow cast by the house itself. Do not forget to water these wall huggers. The following is a short list of climbers that can cope with a short period of drought, once established… Clematis Montana, Fallopia, Jasminum, Trachelospermum and Vitis.
Lawns during a water ban
During a drought, the first part of the garden that people tend to water is the lawn. This is probably because lawns usually make up quite a quantity of most gardens and these lawns tend to look burnt earlier than many plants. However, the lawn would be the last form of plant life within my garden that would receive any rationed water. Lawns are more resilient than you may think, a green lawn that becomes browned off due to water shortage will eventually return after a few heavy rain showers. The burnt piece is the foliage above ground; the roots below ground will sit tight and wait the dry spell out. Of course, lawns comprised totally of fine grass will be damaged significantly by prolonged dry weather, but you should have no worries if your lawn is sown with a utility seed mix .
How to apply water during a drought (if water is available)
I find sprinklers are quite wasteful of the available albeit rationed water, instead I would choose either hand watering or seep watering. With hand watering you direct your watering can or hose to the base of your chosen plant, water deeply at a rate of approx 10 litres per metre squared. Watering lightly will do more harm than good as it encourages surface rooting, which is easily damaged. On many dry soils, water applied directly will tend to run off over the soils surface and away from the plants base, if this happens try the following trick. Sink a two-litre pot filled with gravel at the base of the plant, water slowly into this pot and you will have no run off problems. Seep watering, also known as drip irrigation is an effective and economical way to apply much needed moisture directly. Most well stocked garden centres will sell seep hose or porous pipe, which you will weave between plants within your beds and borders. This seep hose when connected to a water supply will slowly ooze water through small holes along the length of the pipe. It is extremely direct and efficient.
Article by James Kilkelly. James runs a professional garden design service in Galway, Ireland. He has a regular gardening column in an Irish regional newspaper. Visit his website at http://www.gardenplansireland.com/