This Ancient Watering Technique Will Save Your Plants!

Keeping plants hydrated can be a real slog in a hot summer, but over the years I’ve learnt a few tricks that slash time spent watering – including what I reckon is the most water-efficient, time-saving, quite frankly genius (yet centuries-old) method of all…

Time-Saving Watering Tips

When planting thirsty crops like squash, aim to either create a depression into the soil then plant into that, or push the soil up into a ring around the plant. Both methods will help to contain water every time you splosh the wet stuff so it doesn’t just run off over the soil surface.

Similarly, when planting up rows, use a hoe to mark out a shallow trench a couple of inches (5cm) deep, then plant along the bottom. The trench will help to retain moisture every time you water, making the most of every precious drop.

When sowing into seed drills in dry weather, it pays to trap moisture around the seeds to give them a strong start. Water into your marked out seed drill – twice – then sow as usual before covering over with soil. By doing this you’ll guarantee cool, moist conditions right around the seeds. There will be less need to water again for a while, and this means less risk of creating a crust on the soil surface that makes it harder for germinating seedlings to push through.

Planting something bigger, like a fruit bush? Dig out a generous hole, pop your plant in, then fill the hole with water. Allow the water to drain, refill, and drain once more, then return the soil to fill in the hole. You’ve just created a beautifully moist environment around the rootball, so it shouldn’t need watering again for a while.

Water can drain out of containers way too quickly, especially if the potting mix has been allowed to dry out. So, pop a saucer underneath the pot to hold onto the water. Plants can then soak up as much as they need through the drainage holes at the bottom. Don’t leave plants sitting in water for too long – pour away any that’s left after a couple of hours.

Some plants need more water than others, so spot water those that need a drop of the wet stuff, and leave the rest. Unless you’re in a hot climate, established plants will be just fine without extra watering, but young plants or thirsty ones like celery will need a good drench more often. This may seem obvious, but it’s worth bearing in mind so you’re not slavishly moving from one bed to the next on autopilot.

Ditch the Hosepipe

Watering by hosepipe is convenient, but watering cans are usually quicker. They’re instantly refilled by dunking them into the top of a water barrel (covering the barrel back over when you’re done to keep out the local wildlife and mosquitoes). Water pours out a lot quicker from a watering can than from a hosepipe, especially on hot days when high demand can lead to lower water pressure. And you can double the speed by using two watering cans at once. Nice!

One nifty idea I sometimes deploy when it’s really hot and my rainwater barrels have run dry is to relocate one of them so it’s right next to my vegetable garden. Then I fill the empty barrel using the hosepipe and keep the barrel topped up as needed. While hosepipe-delivered water is slower, it doesn’t matter, because I can still dip my watering cans into the water when I need it to get water out that much faster.

Of course, please be careful that the water doesn’t overflow from the barrel – we don’t want to waste it! If you don’t have a rain barrel, you could always use other large, clean containers for this.

Ollas: Hands-Off Watering

Ollas have been used for a centuries – potentially millennia – as a passive watering technique that not only saves as much as 70% of water, but also a lot of precious time. So how do they do that?

A traditional olla is made of unglazed terra cotta. This is really important – it mustn’t be glazed, painted or sealed in any way, because the water needs to be able to saturate the pores within the terra cotta. Then, once that moisture reaches the outside edges of the pot, it will seep out into the surrounding soil.

Traditionally-shaped ollas have a wide body with a narrow neck, and a lid. The olla is buried in the soil right up to the neck, so there’s less surface area exposed to the air, which means less moisture evaporates away from the top.

Bury the olla into the ground, pour water in through the top, pop the lid back on, and then the water will gradually be drawn out into the surrounding soil.

Now here’s the clever part. The olla works because of soil-moisture tension – the water levels want to equalize on either side of the terra cotta walls. So, if the soil is relatively dry, moisture is naturally going to move from inside of the olla to the soil on the outside. If the soil is already wet, this transfer of moisture isn’t going to happen, so the water stays put inside the olla, and the soil won’t get oversaturated. Clever huh?!

Purpose-sold ollas like this are expensive, so let’s look at a cheaper alternative – before we make our own for even less!

Using Terra Cotta Watering Spikes

Terra cotta watering spikes work in a very similar way to ollas. Bury them into the soil or potting mix next to your plants, right up to the rim, then insert a long-necked bottle full of water upside down into the top. This works in a similar way to the traditional olla, but instead of the water being contained within the olla, the bottle acts as the reservoir. The narrow nature of the spikes makes them ideal for use in tighter spots or in containers.

If you don’t like the look of bottles jutting out from the ground here, there, and everywhere, you could use green-colored wine bottles with the watering spikes in among very leafy plants, to somewhat hide them.

Make sure your watering spikes are positioned as upright as possible and pushed right in so that they don’t rock about in the wind, which could potentially crack the delicate spike, rendering it useless. Glass bottles are heavier, so are less likely to get blown about, but keep them topped up with water for extra anchorage.

Make Your Own Olla

Watering spikes cost around a tenth of the price of a traditional olla, but you can enjoy the same benefits for even less than that by making your own olla from terra cotta or clay pots. It’s super easy to do!

Choose a terra cotta pot with relatively thin walls, because this should allow the water to easily pass from the inside out. The first thing we need to do is seal up the drainage hole at the base of the pot because we don’t want the water to just rush out of the bottom – it needs to seep out slowly through the pores of the terracotta itself.

There are a few ways of sealing up the hole, but I find that a waterproof mounting putty or plumber’s putty works best – something that can be moulded into shape then left to set hard and create a watertight seal. Work the putty onto and around the drainage hole, pushing it down nice and firmly to create a proper seal. And for good measure, flip the pot back upside down and do the same on the other side. Leave it to set overnight. Don’t forget to test-fill your olla to make sure it’s watertight before you use it.

Dig a hole deep enough to sink the pot in almost all the way up to its rim, leaving just the very top poking up so that soil doesn’t fall in. Fill it up with water then place a cover over the top. A pot saucer is just the job for this – terracotta saucers are prettiest, but they’ll lose more water from evaporation out of the top, which means they’ll need refilling more often. A plastic lid or glazed saucer won’t do that, so you may want to opt for one of these instead. Keeping the water covered also prevents beneficial bugs like ground beetles from falling in and drowning, and avoids it becoming a breeding ground for mosquitoes.

How to Make a Bigger Olla

You can also make a double-sized olla by joining two pots together. Use silicone sealant or other strong adhesive piped on with a caulking gun to glue the two pots together. Seal up the drainage hole as before, but leave what is now the top drainage hole unsealed, and just cover it with a pebble.

The advantage of a double-headed pot olla like this is that it obviously holds twice the amount of water, so you’ll need to top it up less often. And because it’s buried almost to the top, there’s a lot more of it underground, so less water will wick up into the air and be lost. The disadvantage is that they are a bit fiddlier to fill up, given the relatively small filling hole, so you might need to use a funnel.

Personally, I’m happy to go for a series of single pot ollas. I only need to refill them maybe every couple of days to once a week, depending on how warm it is, what stage growth the plants are at, and the number of plants around it. They’re really great for plants with searching, fibrous root systems like tomatoes and squash family plants.

How to Use an Olla

How far apart you space your ollas depends on a range of factors. As a very approximate rule of thumb, the moisture from an olla penetrates about as far out as the diameter of the pots themselves. Only a little water will get right to the edge of this zone, so ideally, we want to plant around the olla at maybe half this distance.

You’ll need to keep young plants watered as they establish, then once they’ve developed a decent root system they’ll be able to rely more on the olla. You may find that the roots grow around the pot itself, hugging it tightly to draw on all that lovely moisture.

Try to keep ollas consistently topped up – I wouldn’t let them drop below about half volume as we don’t want the walls to dry out then to have to rewet and start over. Avoid the temptation of putting liquid feeds or fertilizers in there, as these could gunk up the pores in the terra cotta and make your olla less efficient. For this same reason I’d aim to use pure rainwater as much as possible.

Don’t leave your ollas in the ground over the winter if you experience hard, penetrating frosts, because the moisture will expand when it freezes and could cause the terra cotta to crack. So if you get cold winters. Remove your ollas before the first hard frosts, let them dry out, then store them till next season.

Let me know how you get on with your homemade ollas. I’m sure you’ll be impressed!