Don't let plants suffer from thirst in hot spell

WE may have had the hottest July day on record and relatively little rain this month, but water companies are indicating they’re not going to introduce hosepipe bans this year, according to a report in trade publication Horticulture Week.

However, gardeners are being advised to take a common-sense approach to watering and not to reach for the sprinkler at the first sign of a sunny spell.

After all, a sprinkler can use up to 1,000 litres of drinking water, or 220 gallons, in an hour, which is more than a family of four would normally use in a day.

There are so many products on the market now to help us save water that there’s really no excuse not to, from controlled irrigation systems where sensors monitor the moisture in the soil and only water your plants when the soil really needs it, to bath water diverters which send all your ‘grey’ water to your water butt.

Add to this an increasing choice of drought-tolerant plants and hopefully the sprinkler will become a thing of the past.

If you must use annuals, which are notoriously thirsty, keep them in pots rather than borders and go for ones which can withstand drier situations, like pelargoniums, gazania and osteospermum.

If you are creating new beds and borders, consider drought-resistant plants such as lavender, Sedum spectabile, lamb’s ears and ornamental grass such as Stipa tenuissima, while middle-sized drought-resistant plants include Echinacea purpurea “Magnus”, Erysimum “Bowles’s Mauve” (wallflower), Russian sage and Nepeta “Six Hills Giant” (catmint).

At the back of the border you could use species more than 1.8m tall, including Cotinus coggygria “Royal Purple”, Choisya ternata (Mexican orange blossom) and Trachelospermum jasminoides. Most drought-tolerant plants will have either aromatic leaves, fleshy and succulent leaves (which store moisture for dry spells), grey leaves, hairy leaves (which shade themselves with their own hairs), long narrow leaves (which are good at shedding heat without water), or spikes (which act as “fins” to cool the plant). Don’t water established lawns - if we have a long hot spell they may turn a bit brown, but they will recover with the autumn rains. Leave them to grow a bit longer to preserve water and introduce drought-tolerant clovers and trefoils which will prevent the lawn from just changing colour completely when a dry spell hits.

Try to recycle water as a matter of course.

Use a plastic bowl for washing up and then deposit the water on to your plants, as a small amount of washing up liquid isn’t going to hurt them.

Save the really dirty washing-up water for tougher plants such as mature shrubs and trees.

Bath water can also be re-used if you install a diverter which redirects water from the downpipe into a water butt. The organisation Waterwise (www.waterwise.org.uk), which promotes water-saving and conservation, recommends attaching a trigger nozzle on your hosepipe to halve the amount of water used and help direct the flow to the root of your plants.

Up to 85,000 litres of rain falls on your roof each year so install a water butt and use it to water your plants and wash your car. If you’re not sure which water butt to buy, check out the Waterwise guide to waterbutts on its website.

Watering cans can significantly reduce the amount of water used while getting the desired amount to your plants.

Don’t water in the heat of the day – do it early morning or early evening to reduce evaporation, and mulch over thirsty specimens to conserve moisture.

If you have plants in pots, gather them together to create a little micro-climate and again reduce evaporation, and you can water them all together. But it’s preferable to use the biggest pot you can afford for patio plants, which will require less watering than smaller containers.

Some more thirsty specimens in pots may benefit from being placed on a tray lined with capillary matting, which soaks up the water and then delivers the moisture to the roots, gradually when it’s needed. It’s handy if you’re going away and don’t have someone to water the garden for you in summer.

Alternatively, place one end of a strip of capillary matting in an elevated bucket of water and the other end in the compost in your pot and it should hopefully filter through over a prolonged period.

With luck, you shouldn’t need to get the sprinkler out this summer.

BEST OF THE BUNCH: AGAPANTHUS (AFRICAN LILY)

THESE beautiful perennials, which bear globes of blue or white flowers above stiff upright stems in summer, used to have a reputation for being tender, but some varieties will withstand frost and come back year after year.

Headbourne Hybrids, for instance, were raised in Britain in the late 1940s, while A. campanulatus varieties can also withstand harsh weather. If you’re planting them in pots don’t give them too much space, as they do better tightly cushioned - although you may have to replant them into a bigger pot every couple of years. Place them in full sun in well-drained but not dry compost.

Move the container next to the house or insulate it with bubble wrap to protect them in winter. If you are planting them in a border, they may benefit from a winter mulch of bracken.

While blue and white varieties are the most common, try A. ‘Twister’ (available from www.thompson-morgan.com), the first deciduous bi-colour agapanthus, which produces globes of white flutes with inky-blue bases.

GOOD ENOUGH TO EAT: GREENHOUSE TOMATOES

YOUR greenhouse tomatoes should now be swelling, so it’s time to take action to ripen the fruits on the lowest trusses.

The most effective method is to cut off the lower leaves around the tomatoes, allowing more light and heat to be shed on the ripening fruits and increasing air circulation which in turn deters fungal diseases.

Repeat this higher up the plant throughout the summer as fruit appears on the higher trusses, and keep removing sideshoot regrowth.

By the end of the summer, you won’t have many leaves left but your tomatoes should be fantastic.

WHAT TO DO THIS WEEK

Pinch out the growing tips of greenhouse aubergines once the plants are 30cm tall to encourage more flowering sideshoots to form

Buy winter varieties of spinach to be sown in August and September to crop between October and April

Transplant wallflowers sown in May or June into rows 30cm apart, leaving 15cm between the plants. Their roots should be strong enough to bed out in October

Sow 10-week stock and larkspur to give you extra colour under glass in winter

Propagate African violets by inserting leaf cuttings now

Water dahlias regularly and feed fortnightly, paying particular attention to young plants which are slow to grow

Peg down runners on strawberry plants that you want to propagate

Reduce the length of wisteria tendrils by half

Plant autumn-flowering bulbs such as amaryllis, nerines, colchicums and autumn crocuses

Feed long-flowering and late-flowering border perennials