How to keep a garden green on less water

Most of it never reaches a root

A garden that needs watering every single day in summer usually doesn't have a water problem, it has a soil problem and a mulch problem, and those are both fixable. Water that runs off the surface, evaporates off bare dirt or soaks past the root zone is water you paid for and the plant never saw.

Fix the losses and you'll water less often, and the plants will actually be tougher for it.

Mulch is the biggest single change

Bare soil in a Strathalbyn January bakes, and the top of it goes hard and hydrophobic, which means the next lot of water beads up and runs off sideways instead of going in. A layer of mulch stops the sun hitting the soil, keeps the temperature down and slows the evaporation right up.

Put it on about 50 to 75mm thick. Thinner than that and weeds come through and it doesn't do much. Much thicker than that and water struggles to get through it to the soil. Keep it back a bit from the stems and trunks, because mulch piled against a stem holds moisture right where you don't want it and rots the bark.

A coarse mulch like pea straw or a bark lets water through better than a fine one, and a fine mulch can set into a mat that sheds water. If yours has gone like that, rake it up and fluff it before you water.

Soil that holds water instead of losing it

Sandy soil lets water straight through. Compacted or clay soil won't let it in at all. Both problems have the same answer, which is organic matter, dug through the bed and topped up every year.

Compost, composted manure, a seaweed based conditioner, whatever you've got. It acts like a sponge in sand and it opens up the structure in clay. It's the least glamorous job in the garden and it does more for your water bill than anything you can buy in a bottle.

If water is beading on top and running off, the soil has gone water repellent and no amount of standing there with a hose fixes it. Fork the surface up, put organic matter through it and water it slowly a couple of times to get it wetting again.

Deep and less often, not a daily sprinkle

This is the habit worth changing. A short water every evening keeps the top 30mm damp and the roots stay up there where it's damp, so the plant has a shallow root system and it wilts the first hot day you miss.

Water properly and less often and the water goes down, the roots follow it down, and the plant sits in cooler damper soil that doesn't dry out in a day. Established plants in an improved bed will often go a week in summer once they're set up that way.

Push a finger or a screwdriver into the bed after you've watered to see how far it actually got. That's the only way to know whether you're watering enough or just wetting the mulch.

Time of day

Early morning is best, because the soil is cool, there's no wind and the plant goes into the heat of the day with a full tank. Evening is the second choice and it's fine, with the one catch that leaves staying wet overnight is what fungal problems like, so aim at the soil rather than over the top of the foliage.

Watering at 2 in the afternoon in a northerly is the one to avoid, because a lot of it goes up before it goes down.

Put the water where the roots are

A sprinkler waters the paths, the mulch and the air. Dripline and soaker hose put the water on the soil under the plants and nowhere else, and on a veggie bed or a row of shrubs it's a big difference for very little money.

Run it under the mulch rather than on top and you lose almost nothing to evaporation. Put a simple tap timer on it and you stop the two classic mistakes, which are forgetting to turn it on and forgetting to turn it off.

Pick plants that suit the place

Something from a cool wet climate will need water here forever, and that's not a gardening failure, it's just physics. Grouping the thirsty plants together in one bed near the tap and letting the tougher things go elsewhere means you're not watering the whole garden to keep four plants alive.

Lavender, rosemary, kangaroo paw, correas, succulents and most of the local natives will handle a dry summer once they're established. The words once they're established are doing a lot of work in that sentence, so water a new planting properly for its first year and then back off.

Catch what falls

A tank or even a few buckets under a downpipe gets you free water for the pots, and pots are the thirstiest thing in most gardens because they dry out from every side at once.

Shop related products

• Pope Drip Eze 13mm x 30m. Dripline for putting the water straight on the soil.
• Pope Simple Set Tap Timer. Stops you forgetting to turn it off.
• Neutrog Whoflungdung Mulch 20kg. Goes on top to stop the soil baking.
• Seamungus Green 20kg. Seaweed and fish based, for getting organic matter into a bed that dries out fast.

Did you know we also stock soaker hose, pea straw bales and gypsum in the shop that aren't all listed online, so give us a ring on (08) 8536 4333 to check what's on the shelf.

The irrigation fittings, the mulches and the soil conditioners are all in the garden centre, and if you sketch out the bed on the back of an envelope we'll work out what dripline and fittings you need rather than you guessing at the shelf.

More from the garden

• How to prevent lawn burn in the summer sun
• How to keep your lawn green, and what usually goes wrong
• How to make compost at home without it going wrong

I am the one who buys the tap timer and then leaves it in the ute for a fortnight, so that tip is very much hard won.

Cheers,
Candeece

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