No need for the jury to retire: Going solar - the outcome

It probably seems like a very early finish to what was expected to be a long running battle between the teams plastic (clear and black) to prove once and for all which one could dominate the reigning champion of weeds - Kikuyu grass.  I too was expecting a close fight between these two behemoths, but sadly, as is all too often the case, I've had to step in to end the contest prematurely, declaring black plastic the winner by a long margin.

The clear plastic was clearly not generating the high temperatures I'd been expecting, only getting warm enough to act as a nice little green house for the grass.  In fact, as you can see in the photograph below, the only damage done to the Kikuyu was caused by the bricks I had used to keep the plastic down.

Clear plastic after two weeks.  Dead area caused by the brick not the plastic.

In the other camp, black plastic, with its amazing powers of light suppression, was making clear inroads into the Kikuyu.  As can be seen in the photograph below, after the same two week period the damage to the grass is obvious.

Black plastic after two weeks.

With such dramatic differences between the two and needing the area for a new garden bed it seemed a sensible decision to end the competition and use the winner.

Clear plastic has its supporters so it obviously must work, but not in my situation. It's probably a combination of climate (temperatures don't often get above 30 degrees Celsius), the location of the bed (it's not 100 percent full sun) and the hardiness of the grass (it's hard to get the plastic tight to the earth).

It's not all bad news though - I've now got about five metres of cloche material :)

And just to prove it's not just me on an anti-Kikuyu crusade.  Below is a poster for a local landcare event scheduled for this Easter - note the competition categories: "Longest Kikuyu runner".

How do you solve a problem like Kikuyu? Going solar.

Probably the first post in what's likely to be a long running series – think Rocky, but with less talent and lower budget.

Let me say upfront: Kikuyu has its uses. It's a good pasture and is quite a good lawn – the sort of lawn you can enjoy walking over barefoot. In our climate, it's set and forget. But, this grass is not a homebody. It likes the jet setting lifestyle and is keen to explore every nook and cranny of your garden, sending out rhizomes like a demented octopus. And once it finds a place it likes, such as my nice new garden bed, it moves in, suppressing all around it (well, all I've tried to grow so far).  So, my challenge is to create safe vegetable enclaves in the semi-hostile territory currently controlled by Kikuyu - all without resorting to extreme chemical measures.

Talking tactics

As far as I can determine there are three main strategies to successfully conquer this persistent little plant – digging, sheet mulching and solarising. I'm currently some way into trials of all three approaches, but unfortunately this commenced before my epiphany that record keeping is a gardener's friend – i.e. I don't have any really good before photos. But, it's still very early days, so better late than never.

Going solar

I started with solarising as I didn't have all the ingredients for sheet mulching and as a new earth gardener is seem a little beyond me. Solarising on the other hand was pretty easy to grasp – get plastic, wet grass, cover grass with plastic, wait. That I felt I could do. And it required much less digging than, well, digging.

There seems to be two trains of thought when it comes to solarising Kikuyu – clear plastic vs. black plastic. Clear plastic will apparently generate higher temperatures than black plastic, whilst black plastic claims light suppression as a key advantage. I started with black plastic as I could get it in greater widths and it was cheaper than clear plastic.

 Solarising: Phase I

I started with an area that I had decided to convert to raised beds and steps after a less agile member of the family tumbled down the grassy slope that dropped away from the house (hmmm, I seem to recall that conversion bit required quite a lot of digging). Anyway, as you can see above, the slope is well covered with black plastic and remained so for about 10 weeks over summer.  I spent my time doing summery things - frolicking in the sea, having picnics and so on.

Until the day of the great unveiling...

Well, to tell the truth I unveiled the top bed about two weeks prior to the photograph and planted out a cover crop to take advantage of some rain we'd had.  But so far there's not a hint that Kikuyu plans a comeback tour.

I'd keep score, but mother nature will always win and claiming a victory will only incite some form of retribution (toads probably).  We'll call it a compromise arrangement currently in my favour.