With another impending hot dry summer, which it seems will become our norm, it is time to think about drought tolerant plants and water retention. Tolerant is the important word because no plant can survive without some water.

A perennial border can be planted with many drought tolerant plants but a vegetable garden is different and needs more planning for if you want quality produce. Where wads of newspaper look ugly in a flower bed, mulching between vegetable rows can really help with retaining moisture. Cardboard or newspaper, well anchored, goes a long way to helping in that regard and also makes moving between rows cleaner. The material will gradually decompose over summer and what is left at the end of the season, might be put into the compost or weighted down to decompose further in situ. When it comes time to rotate the vegetables the following year the remaining material can be reassigned or topped with a new layer. As well as assisting in water retention, this method is a great weed suppressant. It may not look pretty but if it works, it may be worth it. An alternative might be bark mulch which could prove expensive if replaced every year.

Consistent water availability is essential for vegetables otherwise some plants will bolt or go to seed prematurely. They will become bitter in the process. Tomatoes may develop blossom end rot and potatoes may develop scab. More on that later.

This heavily mulched pathway, using bark chips provides another weed suppressing water retaining method.

Des Kennedy Garden.

Gravel is frequently used as a mulch but weeds will eventually grow though it. Unless it is fine crush that can compact and form a hard surface, it is not a favourite due to its permanence.

With the greenhouses opening and a gardener’s need to buy new plants top of mind, I would like to talk about what to look for when choosing drought tolerant plants. To be clear however, all plants need to be well watered, not flooded, but kept consistently damp for the roots to establish. Once the roots have grown down to where water is available and are firmly anchored, then the watering can ease off.

Plants defend themselves from heat and heavy transpiration in many ways. Transpiration is the plant ‘sweating’ – its stomata (small openings for gaseous exchange and water vapour to escape), open and water evaporates cooling the plant. So how do they slow the process of water loss and what strategies have plants developed to retain moisture?

• Some plants are more grey than green. This is because grey, like white, reflects light and less heat is absorbed. Look for plants with grey leaves.
• Some plants grown fine hairs over their stems and leaves. This traps moisture in the air around the leaf and also acts as a reflective agent.
• Some plants store water. The Succulents. Fat juicy leaves store water and often have a shiny waxy coat to protect the sap from evaporating.
• Some plants produce volatile oils. The oils prevent water loss by creating an aromatic shield around the plant.
• Some plants grow water storage units in the axils of their leaves, areas where rain water is trapped in little reservoirs.
• Some plants trap water in their leaves or direct the water back down its stem.
• Some plants have tiny needle shaped leaves with less stomata to transpire water.
• Many drought tolerant plants have very deep root systems to access moisture in the depths.
• Some plants only choose to grow when water is available and will then become dormant.
• Many drought tolerant plants have prickles or thorns. These are leaf adaptations to reduce water loss. They do this by creating shadow and reducing air flow around the plan’s surfaces.

Plants are amazingly adaptive and these clever strategies can be grouped into drought avoidance, drought tolerance and desiccation avoidance.  These features are what to look for when choosing drought tolerant or xerophytic plants. Gardening with mostly xerophytes and water retentive hard landscaping is known as xeriscaping.

Can you match the plant to its adaptation? All these plants are drought tolerant and some have more than one strategy.

Lambs Ears, Artemisia, Sedum, Teasel, Balsam Root, Sunflowers, Lavender, Pine, Bitterroot, Gaillardia, Rudbeckia, Catmint, Russian Sage, Veronica, Russian Sage, Hens and Chicks, Yucca,  Globe Thistle, Sage, Creeping Thyme, Sea Holly,  Coreopsis, Prickly Pear, Holly Grape, Russian Olive, Dusty Miller, Echinacea, Lady’s Mantle, Lupin, Sea Buckthorn.

Using these plants, it is possible to create a xeriscaped garden. You may have noticed that many of these plants, not all, are also deer resistant, a bonus!

A few plants demonstrating their ingenuity at saving water.