Labour Weekend gardens: What to plant to survive Auckland hose bans and water restrictions

Early preparation is the key to keeping the tomatoes planted at Labour Weekend thriving through a hand-watered summer. Photo / 123rf

Top tips for long-weekend gardens that will go the distance (and the surprisingly recyclable water you've probably been pouring down the sink).

Tomatoes, lettuce - and an upturned, cut-down plastic bottle.

Naturalist Ruud Kleinpaste says the best thing Labour Weekend vegetable gardeners can plant to beat outdoor hose bans is a drip-fed watering system.

"Sprinklers are stupid. Only about 60 per cent of the water that comes out of a sprinkler will actually benefit the plants. The rest will evaporate before it hits the ground, or land in places where there are no roots and no point in having water."

Labour Weekend is traditionally when New Zealanders begin planting tomatoes and other summer staples. But with Auckland dam levels low and bans on residential outdoor hosing in place, Kleinpaste says growers need to get smart. He recommends cutting the bottom off a plastic bottle and planting it neck first, about 10 centimetres deep, alongside thirsty vegetable crops.

"Then you fill the bottle, and it slowly drips into the soil, but only around the roots."

A root-targeting watering system reduces the risk of diseases that can occur when a plant's leaves get wet, says Kleinpaste.

"Last year, I grew about 50 tomatoes and not one of them had mildew or blight, just by being diligent and only watering the roots."

Grevillea Fireworks is a dry-tolerant splash of colour. Photo / Supplied

Auckland residents have been using water cans and buckets on their gardens, since the May 16 banning of outdoor hoses connected to the metropolitan supply. Restrictions won't be reviewed until December. The city's dams are averaging about 20per cent lower than normal for this time of year, after one of the worst droughts on record.

Kleinpaste says to survive dry times, gardeners need to take their cue from nature.

"The word is 'biomimicry'. It's not David Attenborough learning about nature, it's learning FROM nature, and using nature's best ideas.

"Look for Mediterranean plants, look for plants that live in deserts. The ultimate one is cacti. These things stand no rain for two years, no problem. The only bastard is when you back into them while you've got a wheelbarrow of soil ..."

Euphorbia glauca, an endangered native plant well-suited to surviving an Auckland summer hosing ban. Photo / Supplied

Plants with silvery leaves reflect sunshine and often store water, says Kleinpaste.

"So you're looking at things like Euphorbia. We have a sensationally beautiful species of this, which, by the way, is an endangered species in its natural habitat. Euphorbia glauca. That's a hot tip for a native plant that is available in garden centres that is really drought tolerant."

Kleinpaste says plants with hairy leaves can also tolerate low water conditions - the natural in-built "hedge" acts like a windbreak, protecting them from moisture evaporation.

Heat-loving show-off Portulaca. Photo / Supplied

Auckland's drought is one of its worst in modern times. In April, dam storage dropped below 50 per cent for the first time in more than 25 years. While commercial users have had some water restrictions lifted this month, households are still being asked to save 20 litres - or about two average buckets - of water a day.

Watercare reports that, from May to October, it received 3338 complaints about alleged water misuse and, while it can recommend Auckland Council prosecute (with offenders liable for fines up to $20,000), so far it was taking an educational approach.

Lamb's ear, protected from moisture loss by its fuzzy leaves. Photo / Supplied

Brie Stafford-Bush, from garden centre group Palmers, confirmed customers were keen for water conservation tips. She says it's still possible to grow traditional summer vegetables, but preparation is key. Edibles need more water when they're first established and then again in their flowering or fruiting phases.

"Tomatoes, courgettes and pumpkins benefit from extra water when their fruit is developing. Peas and beans will develop heavier pods if they're watered regularly after flowering, but too much early on will result in extra leafy growth - and fewer flowers and fruit."

She says gardeners should always check soil moisture before reaching for the watering can.

"You can purchase a moisture meter but a pencil or even your finger will do the trick - pop your finger into the soil, slightly below the surface … if it feels damp, your plant will be fine for another day or two."

Dry-tolerant, sun-loving Gazania. Photo / Supplied

Spreading mulch around plants will help conserve soil moisture, and, for those starting a garden bed from scratch, compost or poultry manure will help lock in moisture.

"Another wee gardening hack? I keep boiled vegetable water and wait for it to cool down before adding it to my garden. Vegetable water holds lots of nutrients that plants love. Pour, grow, eat and repeat!"

Other top tips include getting rid of weeds that compete for water, and collecting the grey water from showers, baths and washing machines, before treating it with an alkaline neutralising fertiliser and recycling it onto the garden. "Dark" grey water (from dishwashers and the kitchen sink) is not recommended for reuse, as it often contains more chemicals and fats.

Native Brachyglottis "Otari cloud" is a tough and showy shrub.

MetService and Niwa recently forecast an average to dry spring and wetter weather in January and February with possible cyclones, but also advise there is little reliability with the long-range forecasts.

Any wet weather may have a bonus silver lining for gardeners. Ruud Kleinpaste says Auckland can be the "city of snails". The good news? Our common brown garden variety is also France's second most popular eating snail.

WHAT TO PLANT WHEN WATER IS SCARCE

• Drought-tolerant (and endangered) natives like Euphorbia glauca

• Bee-friendly rosemary makes a good border or hedge

• Hairy-leaved plants like lamb's ear or borage

• Mediterranean herbs - think thyme, sage, oregano, et al

• Dry-tolerant, colourful show-offs include alstroemeria, gazania grevillea and salvia

• Brachyglottis "Otari cloud" is a tough and showy little shrub

• Hot weather floral star portulaca comes in a rainbow of colours

• Flaxes and grasses add form, natural hues and (double check the label) usually enjoy sunny, dry conditions.