Take me to the river...
Updated: Aug 30, 2018
Now that 2018's great heatwave seems to be finished and the rains have returned, what have we learnt about coping with prolonged heat and drought in gardens? Global warming means we should expect more summers like this ahead so we need to adapt or many plant will die.
Here are some tips:
First of all - does the garden need watering?
If plants have been in the ground for 5 years or more, there should be no need to irrigate as plants should be well established and able to source water as the root systems will have settled in well.
Check the soil too. Dig in a spade depth, if the soil is damp at spade level then there is generally no need to water. If the soil is dry at spade depth then irrigation is needed.
It sounds silly but many people don't know how to water correctly and tend to water the foliage of plants rather than directly onto the soil under the leaf canopy. Learning how to water newly installed plants can save a lot of disappointment and possible replacement costs in the long run.
Irrigation is best applied either early in the morning or in the evening when less water is lost to evaporation in the heat of the day. Watering in the cooler hours really does save on water wastage.
Watering cans can also be used to directly apply water to where it is needed. Some plants may be more able to adapt to the dry soil conditions.
Remove any weeds or unwanted plants that are competing for water and nutrients with the plants you actually want to keep.
If you have a lot of pots in containers, then, if possible, move to a shadier position where transpiration rate of the plant will slow down in the darker conditions.
Check any existing tap connectors, irrigation hoses and adaptors for leakages.
Mulch and work that soil
Add organic matter to the soil if you can. Adding organic matter improves soil structure and moisture retention. This can be applied at any time of year and is vital if planting in the autumn to improve soil structure before the plants are planted.
One of the most efficient ways to conserve water and reduce soil temperature around the roots is to mulch. Can’t say it enough - mulch, mulch, mulch!
Mulch is best applied on moist soils after planting and watering to a depth of 5cm. Mulch as well as preserving water around the roots of plants also reduces fungal infection on plants from water stress. Mulch can be applied in beds, borders and containers. Keep any mulch away from the plant stems.
Organic mulch eventually combines with the soil over time increasing organic matter, improving soil structure and moisture retention.
Strulch - A light and easy to use garden mulch with a neutral pH lasting up to 2 years.
Composted Bark - a fine grade composted bark of 0-8mm. Neutral pH.
Border Bark - a larger grade bark 8-25mm mix of conifer bark. Great for use on larger beds.
Bark Pine Mini Mulch - small neat pine chips perfect for use on smaller beds and to cover soil surfaces in containers.
Decorative Aggregates as Mulch
Many decorative aggregates also provide a cooler zone around the roots helping to combat plant stress in high temperatures and low rainfall. Decorative aggregates do not add any organic matter to the soil.
Popular choices for decorative aggregate mulch include:
Slate. Blue / Plum. Looks great when used over large areas.
Derbyshire Gold Chips. Decorative angular chippings of Dolomitic Limestone.
White Pebbles. For a more contemporary look. Excellent for use on soil surfaces in containers.
There are many choices of hose, nozzles and spray pistols many of which are adjustable to suit the material you are watering. Strong jets tend to misplace soil and reveal roots to the elements thus making root stress even higher and water uptake harder for the plant in the long run. Use a gentle setting to ensure the best water penetration to the soil.
Lawn sprinklers are great for watering large flat areas such as lawns as the name suggests. There are some excellent options on spikes that can be inserted into the lawn or on tripods where the height can be adjusted. Check for coverage when looking at sprinklers - range can vary from 64m2 to 320m2
Drip Irrigation is a great idea for newly installed planting as irrigation sprinklers can be placed directly at the base of the plant reaching the roots effectively and efficiently. Drip irrigation is surprisingly easy to install or you could try one of the starter kits. These are just the thing for containers.
Dripper tube provides a quick, simple and efficient method of watering plants. Each tube / pipe has integrated drippers long the pipe length to deliver water directly where needed.
There is also an option for a self-regulating dripper tube that contains a self-regulating mechanism that ensures irrigation is delivered evenly along the length of the tube.
Drip irrigation is most effective when connected to an irrigation timer which can be programmed to deliver water at certain times of day thus eliminating stress and time.
Watering containers in hot weather can seem like a never ending task. Plants in containers can suffer from water stress to a greater degree than plants in the ground. You can help reduce stress by adding swell gel to compost, apply a layer of mulch to the soil surface after watering. Moving containers to a shady position or placing trays and saucers beneath the pots. Also drip irrigation can be a really useful tool in these situations.
Trees can still be planted at this time of year even under these conditions. Install a tree irrigation system to get water right down to the roots where needed.
There is a lot to be said for the old saying’ right plant, right place’. If this weather is to continue over the next few years then it may be time to reconsider some plant choices that may make dealing with this kind of weather less stressful.
Plant drought tolerant plants. Think Mediterranean / Think Beth Chatto Gravel Garden/ Think Native. Mediterranean plants are used to dealing with dry, hot conditions and as such will require less water to establish. Plants that are native to the UK are also used to adapting to conditions in the UK climate. There is a huge list of plants that will tolerate hot dry weather including plants such as Lavandula, Cistus, Perovskia, Rosemarinus, many herbs, Alpines, Geum, Iris, Nepeta, Stipa, Pittosporum, Buddleja, Buxus, Digitalis, Euphorbia, Trachelospermum, Eryngium, Verbascum, Convallaria, Artemisia, Sedum, Erigeron, Sarcococca, Papaver and Osteospermum will all thrive in hot dry conditions. There are many other choices to select from too.
Water butts. It may be too late for this season but you can install one now ready for use later in the year / next year. Using rain water is a sustainable way to look after your garden as you use less mains water. If you have a water meter you'll save money too.