With most of the UK suffering drought conditions and millions of gardeners unable to use their hosepipes with mains water, things are not good for growers. Welcomed summer heat has given way to enervating recurring heatwaves with scorching days and tropical nights.
Parched ground, not a drop of rain
Even when temperatures are more normal, the rainfall has been next to nothing. Some people have hardly seen a drop for over six weeks. This got me thinking about what we can do as individual growers.
Just like floods, these very dry spells seem to becoming more frequent in recent years. And, just like it’s too late to take out insurance when the house is on fire, it’s too late to do much for this drought. But it may be worth preparing for the next, which may be next year or the year after. I’d bet on next year being dry too – except my predictions are usually wrong!
Resilience
Adding organic matter to soil will increase resilience to drought as well as to flooding from rain. The organic matter – compost and manure – acts as a sponge. It absorbs and holds more water when it rains, storing it for the dry period.
Clay soils are made up of tightly packed small particles, so water doesn’t penetrate and runs off in heavy rain. It dries to a solid hard layer, making it more difficult to absorb the next rainfall. Sandy soils are made up of larger particles with more gaps. Water is absorbed easily, but it runs down below where the plant roots are, making it unavailable for the dry periods. Both are much improved by adding organic matter.
The thicker the layer of organic matter rich topsoil, the more water stored for use by the plants. Aim for a 60 cm layer of topsoil above the base clay or sand. This is not something that can be achieved easily. It took me eight years to get that depth of topsoil. Each year it was dug and tons of organic matter added to the plot.
It does get considerably easier when you have the topsoil deep. All that is needed is the addition of organic matter to replace that naturally lost.
Cultivation
Cultivation can help save water. The soil loses water by plants drinking it and they lose it by transpiration. Just as we sweat, the hotter it is, the more the plant will use. Another loss is from the soil to the air, evaporation.
Water from below reaches the surface by capillary action. Capillary action in soil is the movement of water through tiny pore spaces against gravity, caused by adhesion to soil particles and cohesion between water molecules. It is strongest in finer soils with smaller pores, so clay usually draws water higher than sand, though sand moves water faster over short distances.
Hoeing the surface will break the capillaries and greatly reduce water loss. Simple and very effective.
Mulching with lawn clippings or compost will also greatly help reduce loss by evaporation whilst blocking weed seedlings from light.
Lawns
You obviously don’t want to be digging up and adding organic matter to your lawn each year, but you can increase the amount of organic matter below the surface without destroying the lawn.
Thinly spread a layer of sieved compost over the lawn in spring and autumn. Not to bury the grass, just enough so you can see the top of the leaves. Between worms and rain it will be taken below, The soil will improve, and the grass will grow better for it.
Rather than collecting and removing grass clippings, mow frequently and leave the clippings on the lawn. This can build up a thatch over time, though. Annual scarification (hard raking) will take care of that.
Taking a tip from regenerative agriculture can improve the level of organic matter in the soil. Allow the grass to grow long, ideally to the point where it is about to seed. Then mow it down. Don’t try and mow it in one pass, take three or four passes, reducing the cut height each time.
Grass produces more roots to support longer growth. When cut back hard (or grazed down in agriculture) the grass reduces its active roots. The surplus roots rot down, adding to the humus in the soil. It’s a slow process, but it works. After a few years, I can see the difference in areas where I’ve used this system.
When you know a heatwave is coming, thank you the Met Office, don’t mow too closely. Let the grass grow a little longer than is ideal for a show lawn. This creates a microclimate at soil level and helps preserve the green grass. It does depend on how long the drought goes on for, but worth a shot.
Finally, when drought appears to kill off the grass – it hasn’t. Come the rains the dormant plants come back to life and very quickly begin growing and greening up. A nitrogen fertiliser boost will help accelerate this.
Watering most effectively
Do You Need to Water?
The first question is: Do we need to water? It seems on our allotments that the moment the sun comes out so does the hosepipe. They spray away with no regard to any actual need and often their unnecessary watering does more harm than good. See my video here
Poor Watering Weakens Plants
Just spraying lightly encourages the plant roots to spread out on the surface rather than going down into the soil where the moisture and minerals are. These shallow roots are easily damaged and vulnerable to drying out in really hot dry weather.
Timing
Watering is best undertaken at night or in the evening when the sun isn’t strong. This allows the water to soak in to support the plants rather than evaporating in the heat of the day. If you can’t water late, early morning is the next best option.
Watering by Hand
Pour the water around the base of the plants, if possible, without using a rose. Pour slowly enough for the water to sink in to the soil rather than run off. Concentrating the water to get the most from it. You’re not watering the weeds either, so they aren’t happy. Another benefit.
Sprinklers
Sprinklers are not very efficient but help them by trying to get the spray pattern to just cover the area that needs watering. With impulse sprinklers, you can control the throw distance and the arc.
To judge how much water the sprinkler delivers, place a straight-sided jar in the area and measure the depth of water after a period of time. 10 mm of water is equivalent to 10 litres per square metre.
Soaker Hoses
Soaker hoses are porous hosepipes, usually made of recycled rubber, that allow water to seep out. Being delivered slowly and directly into the soil, little water is wasted and careful positioning enables concentration at the plant roots.
The amount of water delivered depends on the pressure of the water put through. A reasonable estimate is around 15 litres per metre run per hour.
My experience is that soaker hoses often develop pinhole leaks, spraying water rather than seeping. They deteriorate quite quickly and none have lasted me more than three years.
Drip line
I use drip lines to slowly deliver water in the polytunnel and greenhouse border. They can be used outside. It’s a pricey but permanent solution to efficiently water. My drip line is some years old now, but works as well as the day it was laid down.
The pipe emitters compensate for high water pressure, so delivery is slow and steady. The only problem I have found is that, if the tap is turned up full, the pressure in the hose can push it off the corner and T connectors.
I sourced from Access Irrigation who provide all the components and a lot of helpful information on irrigation systems on their website.
Storing water
When we get dry conditions, the water companies issue a hosepipe ban. And, like the East German secret police, encourage people to ‘shop their neighbours’. So the only answer to get water security is by storing your own rainwater from the winter rains.
How much to store is up to you and your pocket. If you take a standard allotment plot of 250 square metres and average summer rainfall of 50 mm, you would need to store 12,500 litres to fully compensate for one zero rainfall summer month. That’s a lot of standard 200 ltr water butts! 62 to save you the maths!
The answer to volume water storage for gardeners is to use IBC tanks, which hold 1,000 litres. Price varies, but expect to pay around £100 each delivered. eBay is a good source.
There’s a good article I published in 2021 about the rainwater harvesting and storage system adopted by Elizabeth Way Allotments, Coventry.
Connecting the taps to the IBCs
I wonder if it would help to put a sprinkling of water retaining gel into the soil before planting? Since having to give up my allotment due to my husbands health, and needing to be at home, I try to grow my favourites in my smallish garden which has clay soil. I just try to grow a row of runner beans in the ground, tomatoes and cucumbers in two small greenhouses, mangetout peas, salad and courgettes in large pots, and spinach under an apple tree. I have 2 large compost bins which I brought from the allotment and a smaller wormery composter, which all help but the ground has still dried out this year.
I remember when I was young my grandfather used to dig a trench for the beans in the autumn and put in the peelings etc, that we now put in compost bins all through the winter, covering each layer with soil. I wondered about trying this out for the bean plot.
Hi Janet
Bean trenches work well, don’t forget to line the bottom with brown card and or newspaper to further help retention. Mulching with grass clippings also helps a lot.