Making the most of your climate

Inside a tunnel house, plants are protected from cold and wind, creating a perfect growing...
Inside a tunnel house, plants are protected from cold and wind, creating a perfect growing climate for more sensitive plants. Photos by Si Williams.
Hoops draped with frost cloth can even out the temperature extremes of hot days and cold nights...
Hoops draped with frost cloth can even out the temperature extremes of hot days and cold nights and extend the growing season into winter, even in frosty Central Otago.
A house has huge thermal mass so next to it can be a warm and sheltered place for plants to grow.
A house has huge thermal mass so next to it can be a warm and sheltered place for plants to grow.

The microclimate at your place will have special features you can enhance and work with, writes Ben Elms. 

It's hard to believe sometimes we can drive 30 to 40 minutes in one direction and see huge climatic differences.

We can drive from Lake Hawea to Makarora and in that 30-minutes we move from an average annual rainfall of about 700mm in Hawea to more than 2m in Makarora.

You only have to watch the greening landscape and lush forests that emerge as you get closer.

Drive 30 minutes from Wanaka and you hit the grapes, apples, stonefruit and booming cherries of the Cromwell region, possible because of the higher sunshine hours and a different climate.

The annual rainfall average here falls to about 400mm.

Drive from Central Otago to Dunedin and you can experience a rollercoaster of temperatures and rainfall averages all the way there.

Wherever you live in the region you are dealing with climatic variables day to day and week to week.

Dunedin had a couple of weeks there in January when it was struggling to break past 15degC.

Central Otago has had one frost-free month so far this year, with a frost recorded in January and earlier this month.

So what to do in these colourful climatic spaces we call home, where we try to grow fruit and veges.

District-wide we need to think about how to create a microclimate in our backyards.

There's not many gardens that would have been calm a few weeks ago, and the wind is a double-edged sword.

On one side it can have a beneficial cooling effect.

Here at Wanaka we have a tunnel house on a north-south axis, so the prevailing winds naturally cool down this space at the height of summer.

On the other side of the sword, we sometimes want to keep the heat in our gardens.

The wind cools down and removes heat, even though it feels like the reverse on a scorching nor'wester day.

In the spring when we're trying to establish seeds and seedlings, the wind can be devastating.

Freshly planted pumpkin seedlings can be destroyed in an afternoon when the winds howl.

Newly sown seed can struggle to emerge.

The soil dries out before the seed has a chance to germinate, or just when it is germinating.

Many a carrot or lettuce crop hasn't emerged as the soil dries up in the spring winds.

Hoops on a vege bed draped with frost or shade cloth have many uses.

They keep the space at a more constant temperature, levelling out the extremes of the cold night and hot day.

They also keep the wind at bay, slowing the moisture's evaporation from the soil and from the seedlings themselves.

Frost-cloth left on over winter will allow many winter greens to grow inside the sheltered environment, protected from the harsh weather outside.

It's a wee microclimate within your bigger garden's microclimate.

We can also increase protection in the vege garden with windbreaks, either permanent walls and fences or shrubs and trees.

Those same fences are key to your microclimate.

Anything between north- and west-facing will reflect sun back into the vege garden.

These spots are great for plants that need a bit more heat; think tomatoes, pumpkins and corn or even a lemon tree trying its luck.

Microclimates can expand your range of plants, and the seasons you can grow in.

There are some key factors to consider on microclimate.

It's all about observation.

Get out there on a cold morning and see where the frost lies and where it is lighter or free of frost.

You might be surprised.

On the windiest days, take a walk around your garden.

Get a feel for the windy spots or wind tunnels.

Keep that wind out.

We've mentioned fences, windbreaks, native shrubs and trees.

As a season progresses, certain crops can be used for their wind and shade protection.

Corn, Jerusalem artichokes and climbing beans are good ones.

Rocks have thermal mass but don't forget your house also has huge thermal mass.

Proximity to ponds and lakes or water tanks is a bonus.

Permanent pathways with pavers or deep, rubble-filled concrete paths trap heat.

Big black barrels of water dotted around will help lift and even out the lows.

The concrete jungle has its advantages in thermal mass everywhere you look.

Reflective heat is a further resource.

Houses, tunnel houses, fences and trees all reflect sunlight back into your vege garden.

Glasshouses and tunnel houses are terrific food-growing spaces, but if they're beyond the budget this year, make some mini ones with a hoop system.

You can buy the hoops or use some ingenuity with recycled irrigation pipe.

You can reuse clear plastic, too.

Raised beds lift your veges away from the frosty floor.

The soil heats up more quickly in the spring, giving you a head start.

That same height will help to keep Jack Frost's freezing tentacles away in early autumn.

Vege beds next to a tunnel house or glasshouse are going to receive extra heat night and day because of their close proximity to a giant heat sink.

They're going to be the last place that gets those late and early unseasonal frosts.

Trees in the right place lift the temperature.

The more trees the better.

But poorly sited they can create too much shade and lower the temperature.

• Ben Elms (aka Dr Compost) gives home composting advice and runs composting workshops. The Dr Compost project is funded by the Queenstown Lakes District Council and delivered by Wanaka Wastebusters to reduce the amount of organic waste going to landfill.



• Dr Compost will be running a free Get Composting workshop in Wanaka at the St John rooms on Thursday March 31, 6-8pm.



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