Drought Tolerance

The experts are saying we’re in for another hot dry summer in South Canterbury, maybe worse than last year. I’m reminded of last summer’s straw coloured lawn, wilting trees, and searing hot water coming out of the hose if I’m allowed to use it. The next thought is for the farmers watching their crops and animals suffer in the heat. That must be even more heart breaking. 

So what can we do to help ease the pain and survive this drought and the next one - we all know it won’t be the last one. Whether you believe in climate change or not, droughts are something we need to be prepared for. There are lots of tips on how to conserve water like getting your dripping tap fixed - seriously it doesn’t cost that much to get a plumber in to fix a drip. See the Timaru Council website for more tips on water usage and the latest water restrictions.

What I really want to share with you in this blog is how to design and prepare your place to do the best that it can. I’m not just talking about your garden but also your business property, the carpark, your school grounds, and even your street. All the outdoor spaces you visit.

Limit concrete and asphalt 

Solid payment like concrete and asphalt do three things that you don’t want during summer:

  1. They absorb and release the sun’s warmth making your place even hotter! Cities with lots of concrete actually record average temperatures 3-5degrees warmer than surrounding rural areas receiving the same weather.
  2. They reflect the light up into your eyes and onto the undersides of plants making them feel more scorched than before.
  3. They prevent rain water from filtering down through the soil and back into the underground aquifers where the wells draw from. Solid hardscape areas tend to direct water into channels and drains connected to the stormwater system which eventually pipes it all out to sea.

Instead of hardscaping with something solid, consider a permeable surface i.e. a material that lets water permeate through it and into the ground. For Example

  1. Gravel
  2. Pavers set on sand not mortar
  3. Porous paving blocks
  4. Gobi blocks
  5. Cobblestones
  6. Specially invented glue for setting pebbles together into a porous pavement
  7. Specially engineered plastic grid and cell products
permeable paving.jpg

Or direct the run-off from your concrete pad to an area of lawn or garden that can handle getting soggy occasionally. Along a road side this solution is called a swale which is a bit like a dolled up ditch.

Rain water tank

Install a rain water tank to collect your own rain water from your roof. There are several shapes and sizes of tanks available these days so you can generally stash one in a place where it won’t be seen or in the way. Better yet design it into a place where it can be seen and used for something else too like a bar leaner or back wall of a bike rack or a circular patio. Get an expert like Wrights Tanks to see what can be done at your place. It might cost a few thousand dollars to install. Think of it as an investment for the future that will be absolutely invaluable when a disaster strikes and water is cut off. i.e. a drought or an earthquake.

Plant trees

They say the best time to plant a tree is 20 years ago, the second best time is now. Ok, maybe not this Summer but come Autumn or Spring next year plant a tree and you’ll be thankful in a few years time.

Also consider not chopping down your existing established trees. Or ask the Council to protect your favourite tree in a public place. 

The benefits of trees far out way the nuisance they cause.

  1. Shade prevents moisture loss from the soil, so your soil stays alive and the so do the plants.
  2. Shade on a hot hot day is much nicer place to be than frying in the sunshine or sweltering inside even when the aircon’s on.
  3. Through the magical act of transpiration, leaves actually cool the air by making it less dry.
  4. Most trees have much deeper roots than other plants so they’re more likely to survive a drought than smaller plants. This in turn helps the smaller plants stay alive too.
  5. Trees provide shelter for other wildlife keeping the ecological diversity alive which means less chance of a infestation/plague on your struggling plants.
  6. Leaves shed by trees provide a natural mulch for plants underneath. Mulch helps the soil retain moisture.

These are just the benefits that relate to drought conditions - among the many other benefits of trees are the fact that leaves converts air+sunshine into oxygen. Isn’t that just magic? They convert Carbon Dioxide into wood i.e. less greenhouse gases in the air keeping the earth too warm. A great avenue of trees and greenery lifts the mood and spirits like no other anti-depressant drug can - that’s a proven fact! Trees along our streets help to create a wall effect which encourages drivers to go slower, i.e safer. 

Plant Choices

Use plants that come from dry climates in the wild. i.e not rhododendrons (from Chinese forested mountains). Here a a few of my favourites:

  1. Rock Rose - Cistus species (from the mediterranean)
  2. Rosemary - Rosmarinus species (from the mediterranean)
  3. Tussocks and Grasses (from Canterbury plains)
  4. Osteospermum species (from Africa)
  5. Libertia grandiflora (from NZ)
  6. Mexican orange blossom - Choisya ternata (from Arizona - USA)

Water features

This might seem counter intuitive to use water for the frivolous purpose of aesthetics but so long as you’re using water you’ve collected yourself from the roof or your own well I think it’s ok. 

Here’s how it will help you survive the hot dry summer months. Water features that allow hot winds to pass over the water’s surface will actually cool the air like an air-conditioning unit. If you position your water feature between a Northerly breeze and your outdoor dining area or better yet, near the windows and doors leading into your home, so the air-conditioned wind can create a cooler environment for you to enjoy.

Just remember that a shallow bit of water will warm up and evaporate quickly so the deeper the water, the more effective it will be. However there is a limit of 400mm deep before it will be considered a swimming pool and therefore need a pool fence.

 

Spatial Layout

Thank about what is where in your space. For example, a carpark is better on the south side of a building rather than the north so they can rest in the shade of the building rather than bake in the sun. 

When you're constructing something for shade like a pergola or shade sail, think about the angle of the sun and where the shade will actually fall. It won't be directly underneath the structure.

Raised garden beds are easier to maintain but the taller they are the quicker they dry out. That’s because they’re warmer and the soil is often light and fluffy so they drain vertically very quickly. 

Locate your vegetable garden to get morning sun, not afternoon sun. Most vegetables only need 6hrs of sunlight a day so in the summer time 5am til midday is plenty. Winter time, not a lot grows anyway so don’t worry too much about maximising daylight hours in Winter. Spring and Autumn are the best times for garden growth and most of this is based on rain and soil temperatures rather than direct daylight hours.

Place a glasshouse so that it gets early morning or late evening sun, not midday sun. This can be a bit of a trick considering there is very little shade at midday. What you want to achieve is longer seasons for more growing days i.e an earlier Spring and a longer Autumn making the non-productive days of winter as minimal as possible. A glass house isn’t much use in Summer apart from frying plants and maybe protecting them from pests…expect you’ve got the vents open to keep things cooler. What I’ve done is positioned my glasshouse between two tall trees so in the middle of the day it is partly shaded overhead but both morning and afternoon it gets low angle sun underneath the branches of the trees.