Watering in drought conditions (July 2018)

High summer is here and we've, so far, had one of the sunniest and driest summers for years.

Newly planted trees, shrubs and hedges need regular watering until they become established, which we usually advise as being for the first two years or so. However, please note the current conditions are now so dry that even fully established and mature trees are becoming stressed due to drought, so please carefully check your garden and water as appropriate. You must ensure that any relatively newly-planted plants are watered regularly and sufficiently as any that fail or die due to drought (or from waterlogging for that matter) would not be covered by any guarantees. If you need further advice regarding the watering of stock you've bought from us please don't hesitate to contact us.

Don't be tempted to water little and often as this will encourage surface rooting and effectively make the tree/shrub/hedge more prone to drought conditions in later years. When you water, ensure that you give the plant enough water for it to soak right through to the bottom of the rootball (obviously in the current weather you may be watering more often than normal, but still give them a good soaking so that you won't have to water as often - if you're on heavy clay soil be careful not to overdo it if the water can't drain away). A good rule of thumb is that an inch of water sitting on the surface will penetrate nine inches down through the soil, as long as that soil isn't too compacted or baked (you may need to lightly spike the surface in these conditions to help the water to penetrate), so if the pot or rootball of the plant was 13-14" (approx 33cm) high/deep when planted you'll need the equivalent of about one and a half inches of water on the surface to soak to the bottom of it which, depending on the width of the pot/rootball, could be two to four gallons of water (or more).

The best time to water is in the late evening so that little is lost to evaporation. Early mornings are good too, but if you see something wilting don't wait for a "better time of day" to water, give it a drink at the root as soon as you can to see it through then go back to it again later.

Water butts are always a good resource in a garden to collect the rainwater off roofing for use in the garden, but the weather has been dry for so long now that, for most of us, the water butts have long since been emptied.

Rather than just tipping it down the drain, ‘grey’ water can be used for watering ornamental plants in the garden. Unless something has already been plumbed in, getting used bathwater to the garden may involve some kind of siphon pump and a hose out of the window, which may be more hassle than we're prepared to put in, as much as we like the idea of it (unless you can somehow divert the bath waste pipe - but for many houses this is shared with the waste pipe for the upstairs toilet - and you certainly don't want raw sewage on the garden, and there are legal issues associated with this too!). However, even with more and more of us having dishwashers at home, most of us still have a bowl full of dirty washing up water from time to time which could be tipped on the garden rather than down the drain. Similarly, if the water from boiled vegetables isn’t going to be used elsewhere in a meal, you can leave it in the pan to cool before tipping it into your hanging baskets; as well as watering them, the plants in the baskets will benefit from nutrients and trace elements from the vegetables.

 

Other issues

In periods of hot, dry weather, avoid applying granular lawn fertilisers on exceptionally hot days, or particularly when the lawn is suffering from drought stress, as these conditions make the grass more likely to scorch. Always read the label and follow the application instructions carefully. The same applies to feeding plants in general; never feed plants with dry roots or when suffering drought or heat stress as this can shock the plant. This drought will have weakened a lot of plants, so many will benefit from a feed after the weather breaks and we finally get some rain.

The stress caused by hot, dry weather, and especially weakened tissues due to drought stress, makes plants more susceptible to certain problems. One of the most common and obvious problems is Powdery Mildew, an opportunistic fungal disease common in dry weather on members of the rose family (apples, pears, Amelanchier, roses, hawthorn, etc), acers, and a wide range of other plants. Fungicides can be used if practical, but never spray in the heat and sunshine of the middle of the day, but ultimately it's best to improve airflow, water the plant (at the root) to help avoid drought stress in the first place, feed (when possible) with a high-potash fertiliser to help harden-off the growth, and avoid composting fallen leaves (dispose of them) to minimise the carry-over of the disease.

 

If you're going away on holiday

If you know that you have a holiday planned and that watering might be a problem, it might be prudent to delay any planting, depending on what it is and on the time of year, until after you get back.

It’s well worth investing in a basic automatic watering system if the need is there; pots and hanging baskets can be grouped together wherever possible to make it easier for setting up a drip irrigation system with a timer connected to an outside tap or water butt. Similarly, for newly planted hedges, a length of soaker hose attached to a timer will efficiently irrigate, usually using less water than traditional methods. With the threat of possible hosepipe bans looming it should be noted that sprinkler systems will of course be included in any hosepipe bans – personally I’m not a fan of them anyway for most uses as they can be an extremely wasteful method of distributing water, not to mention the other problems that they can cause, but they are commonly used by people after first putting down new turf so be aware of the possible restrictions before laying a lawn, especially in the summer months.

Other, more drought tolerant containers can be moved to a shady spot to minimise evaporation, and there are various products available which slowly release water from their own reservoir which can be used to increase the time period between waterings. Established plants in the garden soil should be fine up to a point (see above), but applying a mulch to beds and borders to help hold moisture is always a good idea.

In the vegetable plot, salad crops could well have bolted by the time you return from holiday. Bolted lettuces are really only fit for the compost bin, but if you grow salads as a ‘cut and come again’ crop rather than as whole round heads of lettuce, successive sowings quickly produce more for the kitchen. If space allows you can leave some bolted Rocket in flower as, although it is too bitter to eat, it will attract hoverflies, which will in turn feed on aphids nearby, and if allowed to run to seed this will of course provide plants next year. Indoors, houseplants can be grouped in a bathtub with a shallow layer of water, and standing them on an old towel, which will act like capillary matting, will help to keep them moist without waterlogging whilst you are away.

Unless it's newly laid turf (which shouldn't really be laid in these conditions anyway if possible as the amount of sprinkler watering needed to keep them happy would be huge), don't bother watering lawns as, even though they may look unsightly when dry, they will come back eventually after the weather changes. Don't cut the lawn so closely in dry weather as the longer grass blades will help to shade and cool the roots, minimising the long-term damage.

 

Planting a "Dry Garden"

Of course all of the above are simply methods to help an average garden to muddle through whilst you go away for a short period. If you are likely to be absent for longer periods, or on a regular basis, it would make more sense to have a garden more able to withstand drought and to plan the garden for this from the very start. The basic principles of gardening for dry conditions tend to be a combination of good practice and common sense, such as by minimising the number of container plants which need watering, but most of all in choosing plants which have evolved to cope with drier conditions in the first place. Rather than going into any detail myself here I will simply recommend reading ‘The Dry Garden’ by the late, great Beth Chatto, which was first published in 1978. This book contains a wealth of both guidance and inspiration based on actual practical experience creating a garden on a very freely-draining site in one of the driest parts of the country, as well as on sound horticultural knowledge.