Jo McCarroll, September 2016

Me & My Garden: Sue Daly's productive straw bale vege patch on Great Barrier Island

Sue Daly's straw bale garden on Great Barrier Island

Fancy a vege bed that's cheap, portable and super productive? Why not try straw bale gardening?

I was very impressed by Great Barrier Island's Sue Daly's five "beds" each consisting of three bales end to end in a row. When I visited she had lettuces the size of soccer balls growing, with tomatoes, eggplants, chillies, cucumbers, melons and gherkin seedlings waiting to be planted in any gaps left as the lettuces were picked.

The technique is called straw bale gardening although on remote and sparsely populated Great Barrier Island in the Hauraki Gulf, there were no straw bales to be had for love nor money, so Daly used bales of native reeds which are harvested and baled on the island by a local farmer. Like straw, the reeds have hollow stems which means water and nutrients can penetrate into the bale. 

Great Barrier Island gardener Sue Daly.

Lettuces did well in the straw bale vege beds.

It was the first time Daly had tried this technique she wanted to make better use of a boggy spot. The heavy clay soil on the south-facing slope was impossible to dig, and only kikuyu grass seemed to grow there. So she cut the kikuyu back as short as possible, and put down a thick layer of cardboard (at least three sheets deep) as a weedmat to stop the kikuyu growing into the bale beds. The cardboard was weighted down with wood shavings and long wooden planks. "The planks proved useful to walk on," she says. "The cardboard got terribly slippery when it got wet." Then the bales of reeds were laid on top, with the "cut" side of the hollow reeds to the top.

You can't just grab a bale of straw and plant straight in it, of course. First, Daly had to "condition" her bales for 12 days. The first day she sprinkled three cups of blood and bone onto each bale, the next day she watered them. On day three she added more blood and bone, on day four, more water. She added wood ash and fish meal too. Before she planted anything she made small holes in the top and filled them with potting mix, to give her seedlings a slightly more comfortable start in life. 

To begin with, she says, the bales were so tightly packed she needed to use brute force to make a hole. "I was punching the bales with my trowel! You think you can't get the plants in but, just a few weeks after starting, you can cut it like butter." Adding all that water and nutrients means the bales become mini hot beds, and start composting from the inside out, breaking down into a rich growing medium. Once your bales are up and running, you should be able to stick your finger into the straw; it will feel hot and moist, like a good compost heap.

Daly's first bale crop were lettuces. They grew spectacularly well, she says, as did the cucumbers she put in next: "We had gherkins almost beyond coping." She also did well with chillies, eggplants and tomatoes, which all seemed to appreciate the warmth.

The strawberries she planted in the sides of the bales failed to thrive, but she admits it might be because they went in too late. Onions and potatoes were also a bit of a let down Sue wondered if all the blood and bone she had used made her bales too rich in nitrogen for those root crops. Keeping up the irrigation was hard too. But she is trying the method again this year, and started conditioning her new bales in August. She hopes the artificial warmth created by the decomposition will fool her summer crops into ripening sooner. "We have so many visitors and family who come to the island for Christmas and nothing is ready. This year I want ripe tomatoes, cucumbers and zucchini ready for Christmas Day."

Want to try this yourself? Just be sure to start with straw, not hay. Straw is the hollow stems leftover after harvesting seed crops like wheat or oats, whereas hay is the dried leaves and stalks of grass or clover. So if you use hay not only will water and nutrients run off the top rather than soak into the centre of the bale, the bale will be packed with the seed heads of grass and weeds! 

Reproduced with permission from Jo McCarroll, NZ Gardener - Subject to copyright in its entirety.

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