Carry on Gardening : Gardening topics : Watering

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Reducing the need to water
Mulching
Techniques for watering
Containers
Plants that are drought tolerant

Reducing the need to water

Weather is the most fascinating topic of conversation for both farmers and gardeners. Despite the apparent abundance of water in 2000 we still need to think about how we can reduce the need for watering and conserve what we can.

Firstly, consider the types of plants you grow and whether they are suited to the conditions in your garden. Some soils, such as chalky, gravelly or sandy types allow water to drain through before the plants get a proper chance to use it. Incorporating humus to trap water can make a big difference to the need for artificial watering, although it is important not to create soil which remains water-logged in the winter.

If there are moist and shady areas in your garden, position plants such as hostas there. Likewise, on a sunny well-drained site, the obvious choices will be sun lovers such as lavender, rosemary and the Mediterranean species.

Water is lost from plants through transpiration, the process by which they 'breathe' through the leaves; plant roots are constantly replacing this loss. So, a critical time for the plant will be when it has any disturbance to its root system.

Seedlings will need water, as will any plant that is moved or is newly established. A good soaking after planting settles the soil around the roots and improves the chances of survival. Apply the water accurately around the base of the plant. It is a good idea to ridge soil around large plants to prevent water running away. In hot weather it is a good idea to shade newly planted material.

Try not to waste water on your lawn. Grass will recover from prolonged drought and it is better to ensure that the lawn is cut regularly, but not any shorter than 2.5cm (1 inch). Prepare the ground thoroughly and incorporate as much organic matter as you can. This will improve the condition of the soil and increase its ability to absorb and retain moisture.

Mulching

Water is continually lost from the ground through evaporation and mulching will help to prevent this. Always apply the mulch when the ground is already moist - otherwise you could create an area surrounding your prized plants that will not absorb as much water. Adding a 7.5cm (3 inches) layer of organic or inorganic mulch will:

Improve the absorbency of the soil
Conserve water
Inhibit weed growth
Protect roots from frost and keep the soil a little warmer
Organic mulch will add humus to the soil

A wide range of material can be used for mulches, including:

Home made compost
Spent mushroom compost
Composed bark chippings
Grass clippings
Farmyard manure
Straw, paper, or plastic matting
Grit or gravel

Techniques for watering

Water in the evening to avoid the effects of transpiration.
Water thoroughly - and preferably not more than once a week.
Annuals which have been sown in situ may only need water during the period when flower buds are forming.
Vegetables will need water - but time this to coincide with when they need it most: potatoes, when the tubers begin to form; soft fruit, as the fruit sets; leafy vegetables, as the hearts begin to develop; peas and beans, when they are flowering.
Heavy pruning (if you can bear to do it to a gorgeous new shrub proudly carried home from the garden centre) will, by reducing the leafy growth, lessen the water lost while the plant is establishing itself. Cut back deciduous native hedging plants by about a third; this will ensure the resulting growth is vigorous and bushy. Even bedding plants such as Tagetes and Petunia benefit from having all buds removed as you are planting them, especially if they are a little leggy. This will give the roots time to settle down before expending too much energy in producing flowers.
A 30cm (1 foot) drainage pipe sunk next to a recently planted tree will ensure that water is available to the roots where it's needed.
Did you know that a sprinkler hose used for an hour takes as much water (about 500 litres) as a family uses in two days?
A seep hose is a most economic method of watering
Conserve rain water by having at least one rain butt; catch the run-off from gutters and roofs. Rain water is often better for plants than tap water especially for acid lovers; most tap water is fairly alkaline. Having rain butts positioned at various points in the garden will lessen the need to carry heavy cans of water.
The temperature of water in rain barrels will be similar to that of the soil and so less of a shock to tender plants than water from the main supply. Irrigate plants in the glasshouse with water that has been allowed to warm up a little. How would you like an icy shower when you were enjoying a cosy time in a sheltered environment?
Don't waste water by giving it to plants that don't require it. Herbs will have improved flavour and scent if grown in hot and dry conditions similar to those in their native countries.

Watering accessories

With modern snap fittings and the multitude of hose accessories available, a little expenditure can make your watering very much easier. Lance sprays, fan sprays and squeeze-grip or trigger-grip spray attachments extend your reach and allow a variety of spray strengths for different purposes.

Semi-automatic sprinkler fittings are usually mounted on sturdy bases or spike mounted for firm fixing in the lawn.

Sprinklers are available in a number of different actions offering a range of spray patterns and strengths. These include models with rotating or spinning heads, or gyrating, oscillating or pulsating actions.

Select a sprinkler with a spray action/pattern to suit your requirements:

small circular pattern
large circular/adjusts to half circle
oscillating sprinklers for watering rectangular areas (or part of a rectangle)
border sprinklers producing a gentle arc for a border
'dial' sprinklers which can be adjusted to produce a number of spray patterns: square, circular, semicircular, rectangular and strip
pop-up sprinklers which only appear above the lawn surface when in use a micro misters or mini-sprinklers for individual plants.

Drip watering systems are mostly for special plants where consistent watering is vital. Small-scale pipes are run from the main hose to drip-valve units positioned to drip water continuously into the root zone of each plant. These can lead to soil compaction and while they are most usually advertised as suitable for the vegetable garden, repositioning each drip unit when replanting vegetable beds can be very labour intensive. The most sophisticated have moisture sensors and microprocessor controlled delivery systems.

Very small-scale drip systems can be extremely useful, for example keeping gro-bags moist. Different drip systems are available for use outside and for taking water to individual pots or trays in the greenhouse. Seep hoses have minute holes along one side which can be positioned so that water gently seeps out of them to saturate the surrounding soil area. They are generally expensive. Some are designed to be turned 'holes up' to spray and 'holes down' to seep.

Containers

Obviously plants grown in window boxes, pots and containers are dependent on the water we give them and unlike plants in the ground, don't have access to water deep in the soil. Grouping container plants together provides some protection and it makes sense to move them out of full sun during prolonged dry weather. Standing pots on a layer of moist gravel can help to improve humidity. It is useful to do this with your house plants too.

Container plants will have to be watered at least once a day in warm dry weather. Remember that in windy weather even more water is lost through transpiration.

Terracotta pots can be lined with plastic to help prevent moisture loss.

Plants that are drought tolerant

Shrubs

Buddleja, Ceanothus, Cotoneaster, Cytisus (broom), Eleagnus, Euphorbia, Cistus (rock rose), Helianthemum and many rock plants; Philadelphus, Rosa rugosa, Rosa rubrifolia and lilac.

Silver-leaved plants

Achillea, Artemisia, Senecio, Lavendula,

Nepeta, Santolina, Stachys, Cerastium, Echinops (globe thistle) and Erigeron.

Low-growing plants

Aubrieta, Campanula poscharskyana, Geranium macrorrhizum, Sedum, Sempervivium, Dianthus, Phlox douglasii and varied ivies.

Bulbs

Allium, Amaryllis, Crinum, Gladiolus species and Nerines.

Bedding

Felicia, Gazania, Pelagoniums, Helichrysum, Nicotiana, Osteospermum,Petunia, Cosmos and Portulaca.

Herbs

Sage, thyme, marjoram, melissa, rosemary and fennel.

Perennials and shrubs are the plants to choose for ease of maintenance - as once established they will generally fend for themselves. Watch out for those pretty self-sown annuals found in corners and in cracks, such as Eschscholzia corydalis and Erigeron; all of these will happily thrive in hot dry conditions.

Publications

Thames Water Waterwise fact sheet
www.thames-water.com

The Dry Garden
Beth Chatto, 1998
Orion
ISBN 0 7528 1642x

Or the converse The Damp Garden
Beth Chatto, 1998
Orion
ISBN 0 7528 16438