Trumping Jack in the garden

Cloche hoops and tunnel houses create a milder micro-climate for vegetables through the winter.
Cloche hoops and tunnel houses create a milder micro-climate for vegetables through the winter.
Ben Elms checks his cloche hoops are secure before covering them with frost cloth. Photos by...
Ben Elms checks his cloche hoops are secure before covering them with frost cloth. Photos by Simon Williams.

With the seasons changing, Ben Elms shares a few tips and tricks to keep Jack Frost at bay.

Jack Frost has become a new hero for my son this summer with Dreamworks' latest movie Rise of the Guardians.

Alas, Jack Frost does not hold the same hero status for us gardeners. He's more the foe who never dies, coming back to haunt us time and time again.

So how can we combat Jack, and stop him and his winter buddies Southerly Wind and Bone-Chilling Rain demoralising us in the vegetable garden? If you have the luxury of starting from scratch, situate the vege garden on a north-facing aspect which is sheltered from the wind.

Thermal mass can help create an ideal spot for growing. Look at what you have to work with: north-facing walls, especially stone or concrete, catch the sun and radiate heat outwards during the night. Courtyards often create their own microclimate, staying a few degrees warmer than surrounds.

Medium to large trees in the immediate area have a cooling effect in summer but can help to ward off those unseasonal frosts.

I'm always amazed at how few water tanks I see used in rural areas, particularly those subject to Jack's frosty sword. These are gigantic balls of thermal mass. Building vege gardens around a water tank means you can grow frost-tender plants (pumpkins, tomatoes and corn) around and over it during the summer, and then move on to leafy greens in the winter.

Covered structures can help extend the growing season and also provide a safety net in a cooler summer or an unsettled early spring. Tunnel houses, glasshouses and large cloche hoop systems can aid us in this mission of harvesting vegetables year round. They still get cold inside, but the bitter edge is taken off.

Some strategic thermal mass will raise the temperature inside, even on the coldest nights, by storing the sun's heat and releasing it after dark. Options include deep concrete or rock paths, black barrels filled with water and brick walls built on the south side. Another trick is to cover plants with frost cloth inside your growing house. You can install some cloche hoops inside to make it easy to do.

Not everyone has access to a tunnel house or glasshouse, but you can easily create a mini-microclimate by using cloche hoops and covering a section of your garden with plastic frost cloth or wind-break. You can buy ready-made hoops or build them yourself from some scrap metal or used irrigation pipe. For the cost of a few dollars, you can harvest fantastic leafy greens all winter under a cloche system.

Getting your location and cover sorted is important, but the key to winter veges is getting the seedlings in the ground soon enough. Timing depends on your region and climate and even then it can be a bit like Russian roulette depending on what the weather decides to do.

Many people do not start planting winter veges until they notice the days are getting cooler, but by then it's too late. The key is to sow seeds often and early, or to buy and plant seedlings.

In Central Otago, and most other regions, you need to plant leafy winter veges from early February onwards.

The secret weapon we have on our side is plant varieties. There are a whole load of vegetables that will grow over winter (even if only a little) or will at least survive until you harvest. Let's give it up for those ''cut and come again'' leafy delights, such as mizuna, mibuna and miners lettuce, which will all grow a fresh crop if you leave a few centimetres of green when you harvest them.

You can feed your family as many healthy greens as you loke with these in your arsenal.

Ben Elms (aka Dr Compost) gives advice and runs workshops as part of the Dr Compost project to encourage home composting and reduce waste, funded by Queenstown Lakes District Council. He will be running a winter gardening workshop in Wanaka on Thursday, March 14. Visit for details.

Top winter veges

Almost no need to say anything about this hardy old fave, but there are some interesting varieties to choose from. Pick the outer leaves and it will keep on producing for you.

Mizuna and mibuna
These Asian greens sound similar and like the same conditions, so let's group them together. Harvest them using the ''cut and come again'' technique or by harvesting outer leaves. Prefer to be grown under cover in the depths of winter.

Miners lettuce
This will grow abundantly outside. Allow your plants to go to seed at the end of the season and you will be rewarded with even more plants next season without having to sow any.

Get started outside early. A well-established plant will survive nearly all frosts. Happy inside too.

Add some spice to your winter salads. Rocket grows best in spring and autumn, and will grow under cover over winterKaleLots of varieties and so many uses: we love you, kale. Plant heaps outside now.

Yes, some varieties can withstand those freezing temperatures, but best planted inside a tunnel house or glasshouse. Varieties to grow include cos, merveille des quatre saisons and freckles.

Carrots and beetroot grown over summer and autumn months can be harvested over the winter months. Give them a deep cosy covering of straw to keep Jack Frost off them. Dig them up as you need them.

Give komatsuna, corn salad and minutina a go. More leafy greens to keep scurvy at bay.

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