Watering should be the simplest thing in the world, but watering effectively and efficiently requires a little know-how. How you water depends on the type of plant, the stage of its lifecycle, and the conditions you’re growing in, including temperature, how sunny it is, and your soil type.
I’ll share everything you need to know to keep plants quenched and your garden thriving. We’ll look at when and how to water, which plants to prioritise, and I’ll be revealing some clever water-saving ideas that’ll even save you time, too!
When to Water Plants
How do you know when to water? Well, most of us have the perfect portable tool for determining this: your index finger! Pop it into the soil, down to where the roots are, and have a feel. Does the soil feel cool and moist to the touch, or is it dry and dusty down there? Water if dry.
It’s best to water in the morning if you can. The soil will be cool from the night, and plants can fill up on water ahead of the day’s heat. Plants grow more during the day, so loading up on moisture ahead of expected growth makes sense. Watering in the morning also means the soil surface has a chance to dry before nightfall, making plants less susceptible to slugs and diseases.
That said, not everyone has time in the morning – perhaps you have to rush out to work or go on the school run, and don’t fancy getting up extra early to fit it in. No problem – watering in the evening comes a close second, and to be honest, this is typically when I water.
Whenever you water, just try to avoid the hottest part of the day when water evaporates far quicker, leaving less for your plants.
Which Crops Need Water When
As the saying goes, different strokes for different folks – and that’s certainly true for our crops.
Seeds and Seedlings: The highest priority is watering seedlings and young plants which won’t have expansive root systems yet, and which are more vulnerable to dry conditions. Extra water at this early stage will help plants to establish successfully.
Leafy Crops: Leafy vegetables like lettuce, chard and cabbage are some of the thirstiest crops, requiring consistent moisture. Heading types of lettuce and cabbage especially need this as they start to develop and firm up.
Root Crops : Potatoes need plenty of moisture as the tubers start to form. Other root crops like carrots are more self-reliant, but water before the soil totally dries out so growth isn’t checked.
Peas and Beans : Step up watering of peas and beans once flowering begins. These guys need plenty of moisture from this point on if they’re to successfully set and swell their pods, though French beans are more tolerant of drier conditions than runner beans. I find that climbing beans need a lot more water than dwarf beans, simply because there’s so much foliage to support, so keep them well quenched!
Alliums : Alliums like onions and shallots are more tolerant of dry weather, but grow faster if water isn’t limited while they’re establishing.
Stem Veggies: Veggies like celery and fennel are much thirstier and will bolt (flower prematurely) if it’s too dry, so water them consistently.
Fruiting Veggies : And then we have our fruiting vegetables, such as tomatoes and eggplant. These need consistent moisture from the moment the first fruits form to encourage steady ongoing production. This will also help to avoid complications that arise from irregular watering, for instance split fruits, or nutrient deficiencies like blossom end rot.
Symptoms of Water Stress in Plants
Plants often give visual cues that they’re water-stressed. Sparse foliage or a lack of pods or fruits can be a signs that they’re struggling. Leaves may lack the luster of a healthy plant, or they might be drooping or wilting. Container plants might become very light or easily blow over. And water-stressed plants are far more likely to come under attack from diseases like powdery mildew, a common disease of vegetables like peas, beans and squashes.
Get to know your plants and read the symptoms. And, as I say, test soil moisture with your finger regularly as some of these symptoms, would you believe it, can also arise from overwatering – so you want rule that out before sploshing about more of the wet stuff!
How to Water Plants
Water nice and deeply, and as close to where the ground, where the roots are, as possible. Overhead sprinklers make me wince, because so much of that water lands on the foliage and just evaporate or sit around increasing the humidity around plants, which raises the risk of disease.
Get the hose or watering can’s spout close to the base of plants and aim the water at the soil to avoid wetting leaves as much as you can. This way every last, precious drop is delivered right down at ground level, which you can then lock in with a mulch (more on that shortly…).
Water each area thoroughly before moving on to the next, then return to the same area and water all over again. The first pass softens up the soil surface, making it more receptive to the second pass of water so that more penetrates second time round.
The mantra ‘little and often’ is great for so many things – but not watering! The water needs to really penetrate the soil, ideally down to a depth of at least 6in (15cm). It’s a case of ‘more, and less often’!
Dampening only the uppermost layer of soil encourages roots to form just below the surface, making plants a lot more dependent on regular watering. But by watering deeply, roots are forced to search out moist soil further down as the top layers of soil dry out, resulting in resilient, self-reliant plants.
Sandy soils drain through and dry out a lot quicker, so are likely to need watering more often. Heavy clay soils dry out slower, but may need a more sustained drenching to rewet if they dry out completely.
Watering Containers
Plants in containers are vulnerable souls because they can’t send roots deep down or far and wide, so available moisture can quickly get depleted.
Drip irrigation can help particularly demanding plants like tomatoes to stay quenched. In hot weather, group pots together to cast mutual shade, and so you can water them more quickly and easily.
Peat-based potting mixes dry out quicker than soil-based mixes, which have more density to them and, therefore, a higher water-carrying capacity. Another option is to mix in water-retaining gel or crystals, which take on lots of water, swelling to many times their original size, to then release over time as things dry out, thereby helping to smooth the peaks and troughs between waterings.
Conserving Water in the Vegetable Garden
Watering by hand takes time, which is why conserving water – so it lasts longer – is a wise move.
The best way to improve any soil so it holds onto moisture for longer in dry weather – and drains better in wet weather for that matter – is to add a mulch of organic matter. Organic matter is anything derived from living materials – so, for example, garden compost, well-rotted manure or leafmould – anything that was once alive will add valuable goodness to the soil.
Improving soil like this is a gradual process, done over many seasons. I like to add the bulk of my organic matter to the soil surface in the winter months so it has time for soil organisms to incorporate it ready for sowing and planting into in spring.
Then once the growing season’s here and plants are growing, I mulch again to create a barrier between the soil and the air. This reduces evaporation by as much as 70% while also suppressing weeds, which will tire themselves out pushing through all that mulch to get out into the sunshine.
Lock in moisture by laying mulches at least an inch (3cm) thick after you’ve watered or following a sustained period of rain. Dry grass clippings also make great summertime mulches, but spread them in thinner layers to prevent them matting into a soggy mesh – they can always be topped up as they disappear down into the soil.
You can also use water-permeable plastic mulches that sit on the soil as a barrier between it and the air. These can be great for chunkier vegetables like onions and potatoes, or perhaps big old squashes. Woven mulches are popular, but you may want to avoid them because of the plastic. In which case, use cardboard: it’s usually free, it can be laid in sheets to smother the ground and – would you believe it – it rots away by the end of the season, helping to improve the soil in the process. Lovely stuff!
You can even plant through cardboard. After laying it, simply cut an X-shape where you want to plant, fold back the cardboard, and plant into the soil underneath before returning the flaps. To finish things off, add bark chippings or other organic matter on top of your cardboard.
Save and Store Water
Rain is better for our plants, and collecting it both saves money on metered water and reduces watering problems caused by hosepipe bans, which always come at just the wrong time! Set up as many water barrels, coming off every roof surface, as you can – the bigger, the better!
Save water from inside the home too. Catch any water you wash or cook vegetables in and, once cooled, throw this out onto parched ground. Bath and shower water can be used too, but only if you use ecologically sound products, and only around non-edibles like flower and shrub borders.
Don’t forget to keep yourself well hydrated – we don’t want you wilting either!