Don't Make Rookie Watering Mistakes in the Garden

#1. Watering Too Little (or, Yes, Too Much)

Every gardener has over-watered or under-watered. What is too little water, or too much? 

The symptoms of plants struggling with too much or too little water are often the same: drooping or curling leaves and a sorry-looking appearance. So how do you know whether it’s down to overwatering or underwatering?

1. Be guided by the current conditions and give this some thought. If it’s hot and you’ve not been around, chances are your plants are gasping for a drink! If it’s dull and cool and you’ve been watering every day, your plants are probably drowning!
2. Look at the plants itself. Plants that are beautifully hydrated have good, green leaves; they’re generally lush and thriving. Plants that are suffering in heat have leaves that are curling/going a bit floppy simply due to the heat. You’ll see this on tomatoes and zucchini. But watch them once temperatures have recovered.  Sometimes plants react to the heat in this way and it’s not necessarily down to lack of water.

How to tell if your plants need watering? Here are a couple ways:

1. The finger test: push a finger down into the soil to feel for moisture. Cool and damp versus dry and warmer.
2. The weight test: Pick up a container or tub and gauge its weight. I can even judge the weight by simply pushing the container with my foot to make a call on weight.

The common causes of under-watering is to pass the hose over the surface too quickly so it gets wet, but the water doesn’t penetrate enough. Again, do the finger test to check if in doubt.

If you’re growing in pots, bear in mind the size of the container. Larger containers have much more potting mix in them, which means there’s more for plants to draw on. This should mean they need watering less often. Again, pick up or push your pots to judge their weight and how moist they are.

The temperature, how windy it is, how much direct sunshine plants are getting – these are all factors to consider when getting a feel for how much water to apply and how frequently.

#2. Watering Incorrectly

Closely related to how much water we give our plants is the way in which we apply it. 

1. The first thing to do when our soil is dry is to go over it thoroughly. Methodically water one bed at a time and then move on to the next and then the next. Then go over the whole lot again and repeat the process. This way, the first drenching has a chance to drain down into the soil, so it’s receptive to the second drenching, and really drives that moisture deeper down.
2. Aim water at the base of plants. Water simply evaporates from the leaf surface, rather than going down to the soil where the roots are. Wetting the leaves isn’t the end of the world for most crops but what it is, is a waste of water. 
3. This is where soil-level irrigation comes into its own. Drip irrigation, soaker hoses – anything that delivers water at ground level is going to get much more water to the roots than water applied willy nilly from overhead. 
4. Many gardeners prefer to water by hand because it gives us time to think – and inspect plants. But, for larger crops like tomatoes and corn especially, get in there among the foliage, aiming the water right at the base of those plants.
5. Especially avoid wetting the leaves of more disease-prone plants like tomatoes or potatoes. Wet leaves encourage problems such as blight. It can be hard to avoid wetting the leaves of seedlings and young plants of course – and, look, it’s fine at that stage. But just try to avoid wetting the leaves of the most at-risk crops.
6. Then there’s plant type and stage of life to consider. Not all plants should be given the same amount of water. Seedlings and shallow-rooted crops like beans may need watering more often as they can’t draw on moisture from that far down. Root crops like carrots and other veggies that go down deeper will be more self-reliant and can go longer between waterings.
7. Larger plants producing juicier, fleshier fruits will of course need water – I’m thinking of the likes of cucumbers, tomatoes, squash and zucchini or courgettes. More water in equals more fruit out, but of course consistency is important to avoid issues with fruits cracking or splitting.

See the Almanac’s page on When to Water Garden Vegetables.

Watering Containers

And finally on this point – let’s talk about how to water dried out containers. Water will just run straight down the sides of potting mix that has shrunk away from the walls of the pot because it has completely dried out. It simply doesn’t soak in. Instead, re-wet by standing the container in water to soak up water gradually. Don’t let it get to this point – regular watering should avoid this ever happening!

#3. Watering at the Wrong Time


It’s tempting to water in the middle of the day – after all that’s when plants are hottest and probably thirstiest right? Wrong! Yes, they’re hot, but if you’ve watered earlier in the day they’ll be just fine. There’s a bit of a hierarchy of when to water, and top of that is first thing in the morning.

• Watering in the morning sets plants off to a flying start. They’ll have plenty of soil moisture to draw on and will be stronger to face the heat of the day. It’s a great way to start the day – a little commune with nature when it’s quieter and a good boost for your mental wellbeing. It’s a calm moment to psych yourself up for the day. It will also mean the soil surface will dry off as the day progresses, meaning fewer problems with soil-borne pests like slugs or diseases.
• But not all of us have time in the morning. Or maybe you just want to wake up slowly. Watering later in the afternoon or early evening is the next best time of day. There’s still time for the soil to dry out a little, and the worst of the heat of the day will have passed, ensuring less evaporation from the soil surface and more moisture left in the soil to support plants the following day. Let’s be honest, this is when many of working stiffs tend to water.
• But all of that aside, if plants are struggling, water them at any time of the day – don’t hang on until the ideal time – get in there and save them!
• Clearly this is where an automatic irrigation system – set to a timer – can prove invaluable. Set it to water at the optimal time of day and let the system do the work for you.


  
  See the video below in which Ben demonstrates the proper way to water!

#4. Not Collecting Enough Rainwater 

Rainwater is best for our plants. Mains or city water is good enough, but with the high levels of chlorine used to treat the water, it isn’t ideal, and it can be alkaline, which is a definite no-no for acid-loving plants like blueberries. Rainwater is free, unlike treated water which can cost quite a bit in some areas, especially water-stressed regions.

A rain barrel coming off an outbuilding harvests rainwater from quite a big area. The result is that it recharges from empty during just one rainstorm. It’s beautiful stuff, and in this shady area and with a lid, it stays nice and cool and clean – no algae. That said, you can water on water contaminated with algae so long as you’re not going to eat the parts of the plant that come into contact with the water. 

You can connect rain barrels to any roof of course. This one’s on my greenhouse but imagine how much you’d harvest from your house roof. You can even link up rain barrels.

A quick word on water harvesting restrictions in some states. In almost all cases it’s fine for garden use – and in fact actively encouraged. But if you’re planning a big setup, just check – to be on the safe side. Learn more about rain barrels.

#5. Not Covering the Soil

If you have a long period without rain or a strong heatwave, this can be do a good job of drying out the soil till it turns dust dry or rock hard.

• The best way to keep moisture in the soil for longer, and thereby reduce the frequency we have to water, is to cover the soil. But many of us are guilty of leaving soil uncovered. You wouldn’t go out into the hot sun without some sunscreen – well it’s kind of like that for our soil too. Also consider the erosive effect of wind – we’ve all seen those horrifying clips of topsoil being blown away by strong wind; well a mulch should prevent this.
• Once the soil is well watered and a mulch is applied, it will slow down evaporation, locking in moisture for longer.
• Organic mulches – that is mulches that will eventually rot down into the soil – are best because they will feed the soil as they break down, but any cover is better than none in a hot summer.
• You don’t need to spend much on fancy mulches. Try straw on the potato beds and around tomatoes (not hay, no seeds!). Dried grass clippings around leafy greens are another option. You could also use wood chips around my fruit bushes. Pine needles are another great option, or just more garden compost.
• Mulch also stops the soil splashing up onto the foliage – this is great for crops like tomatoes that are prone to soil-borne diseases like blight. It keeps everything clean, and it cushions the water you add, so it doesn’t compact the soil surface or lead to a hardpan and runoff over the surface. And it keeps the soil cooler in hot weather – great news for soil life – everything from earthworms down to the micro fungi that help our plants thrive.
• Shallow-rooted crops will especially appreciate a good mulch. And you can mulch containers too of course. 
• If it’s really hot, you can use shade cloth to slow evaporation.

How do you make the most of the water you use around the garden? Share your own ideas and tips in the comments below.  Keep your cool out there!