Drought

growing drought-tolerant plants

By Bridgette Saunders

Photo: Illustrative image for the 'Drought' page

One way to cope with the problem is to grow drought-tolerant plants.  These tend to put on growth in spring but have reduced water needs in summer and are typically from areas with a Mediterranean climate – cool, moist winters and hot, dry summers. 

Many drought tolerant plants have silver or grey-green leaves, their light leaf colour reflecting the harsh rays of the sun. Some have a coating of fine hairs on their leaves or stems, helping to trap moisture around the plant tissues. The RHS have completed a trial of drought tolerant vegetables. See the table right. 

Many plants have adapted to drought conditions – here are some examples of how plants have evolved to cope with much less water – many of which are suitable for growing on your allotment.  Don’t forget that plants are much better than weeds – which take water from the soil – so grow ground cover plants such as Stachys byzantine (lambs ears) instead.  You can often pick a cutting or two up from a friend and start them off in a pot before planting them out.

Small leaves shed heat and have few pores from which to lose water. Good examples are Rosmarinus officinalis (rosemary) and Thymus (thyme).

Long, narrow leaves are very good at shedding heat without losing water. Plants with these include grasses (eg. Helictotrichon sempervirens) and phormiums.

Grey leaves usually signify drought resistance. They can typically be seen on ArtemisiaLavandula (lavender), and Verbascum.

Hairy leaves shade themselves with their own hairs. Verbascum bombyciferum and Stachys byzantina (lamb’s ears) are just two easy-to-grow examples.

Leathery foliage loses less water than soft leaves. Look out for plants such as Salvia officinalis (sage) and Cistus ‘Silver Pink’.

Waxy leaves have a shiny surface created by the waxy cuticle in which they are enveloped. This reduces evaporation, particularly in windy conditions: examples include pine trees, Pittosporum , Acacia and Eucalyptus.

Fleshy, succulent leaves store moisture for dry spells. Sedum spectabile (ice plant) is a hardy example, while Aeonium can be grown outdoors in summer.

Aromatic leaves contain volatile scented compounds that are thought to cool foliage as they evaporate, reducing water loss. Try Cistus and Lavandula.

Spikes act as ‘cooling fins’, ensuring plants like Acanthus spinosus (bear’s breeches) and Eryngium oliverianum (sea holly) lose heat but not too much water.

Slow growth By restricting growth of both stems and leaves, plants can conserve limited supplies of water (e.g. many cacti and succulents, including Sempervivum arachnoideum).

Underground storage organs enable plants to save water for long periods of drought (e.g.daffodils, Dahlia, Eremerus).

This page was added by Melanie Matthews on 04/06/2011.
Comments about this page

Regarding the article.... it was indepth and has helped out a lot. I have found that in the past when I have not been able to water I have had fruit and veg. though they are smaller and less in volume but it is not the end of the world. In a commercial point of view its a disaster but in an allotment situation its all good. Maybe next year you can take the following steps above.

By joseph rudwick
On 25/06/2011