With the significant majority of vegetables and fruit consisting of water (somewhere between 74 per cent for sweetcorn/corn and, in the case of cucumbers, 96 per cent) the ability of our crops to access the wet stuff is pretty important in determining the final weight of harvests. It doesn't take the brightest brain to work out that if your plants have access to as much soil moisture as they require, they will grow faster, bigger and better.
Alas, hot, dry summers will either thwart your chances of decent results or necessitate considerable effort applying prodigious quantities of water. Tap water takes a lot of energy to treat and distribute while metered water can prove expensive. With droughts an increasing phenomenon in many parts of the world (even where I am in often-drizzly Britain) the more we can do to reduce our reliance on the tap the better.
In most growing seasons some watering will be needed, but it's not how much you apply that counts, it's when and where. Watering efficiently at the correct time can save many, many gallons of water over the course of the average summer.
Young seedlings and fleshy leaved salads need consistently moist soil if they are to thrive. Other plants are more tolerant of soil that dries out from time to time. As a general rule it is better to water really thoroughly once a week or even every two weeks than to dribble it on little and often. Token watering that merely wets the surface will encourage roots to sit at the surface rather than grow down to seek deeper soil moisture. It will create plants that are completely dependent on frequent watering for their survival.
While soil may look dry on the surface, it may be adequately moist below ground which, after all, is where your vegetables' roots are. Not sure? Just dig out a spade's depth of soil and check the moisture of the soil profile. If it's dry, water well. The object is always to persuade roots downwards to encourage self-reliance.
Sowing and planting
Perhaps the biggest influence on how a plant establishes is how it's watered at sowing or planting time. When sowing seeds begin by watering once or twice along your marked out seed drill before spacing your seeds and filling the back with soil. This creates a lovely moist area around the seeds and, in hot weather, will help to cool the ground slightly, ensuring cool-loving veggies such as lettuce germinate without fuss.
Similarly, when planting out young seedlings or plants raised in modules start by filling the planting hole you've made for each plug with water. Allow the water to drain, fill with water again, then allow to drain once more before planting as normal. The advantage of this simple technique is that roots will be encouraged into the soil to ‘chase' the moisture as it filters down.
The same method of filling, draining, filling, draining can and should be applied to the planting of larger fruits trees, shrubs and any container-grown plant. Known as ‘puddling', charging the soil with moisture like this makes a dramatic difference in how quickly a plant gets off the ground. As an added bonus the soil surface is kept dryer, which reduces the inevitable flush of weeds seen when watering from above.
No matter what type of soil you have it can always be improved with the addition of organic matter – be it compost, matured manure or anything else that's well-rotted and ready for action. Sandy soils that drain freely will be the first to dry out but the regular incorporation of organic matter will bind the grains of sand together to create more of a crumb structure that will hold onto soil moisture for longer. The mirror image is true for sticky clay-based soils where organic matter will help to form a crumb structure that ensures better drainage while reducing that hard-baked and cracked effect you get during a dry spell.
During the active growing season, with crops in full growth, the same organic matter can be applied as mulch. This slows evaporation from the soil by acting as a physical barrier between soil surface and the drying actions of sun and wind. It will also hamper weeds while providing additional nutrition and steady improvement of soil conditions as resident worms work to ‘dig in' all this goodness. As well as well-rotted organic matter you could also use grass clippings, straw, disease-free veg trimmings or, around fruit trees and bushes, chipped bark.
Of course, as well as conserving water it's good news if what you do apply is rainwater you've diligently harvested. It's free, resource-savvy and better for your plants. Take a look back at my earlier advice on rainwater harvesting.
There are other ingenious ways to naturally maximise what rain does fall – useful techniques developed in dryer climates where every drop isn't just valued, it's truly precious. Lots can be taken from our advice in dryland gardening and applied to even temperate regions of the world where dry summers may still be a potential stumbling block.
Lots to do with saving water in the vegetable garden is common sense and can be summed up through these five golden rules:
- Feed your soil with organic matter to create a buffer against extreme wet and dry.
- The most important watering opportunity is on planting or sowing.
- When watering, apply plenty of volume, less often to encourage deeper rooting.
- Mulch to conserve soil moisture and improve soil structure. It really works!
- Collect as much rainwater as you're able to save using treated tap water.
By Benedict Vanheems.