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Helen McKerral

Helen McKerral

January 25, 2012

One of the biggest gardening challenges for any owner of a new, bare block, is mulch. Established gardens generate mulch as leaves and twigs, or weeds and prunings that you pile in a heap or in the chicken run to let the ladies do their work. If you don’t have chooks, compost bins are great for kitchen scraps, though the mulch they generate is often high in nutrients and low in volume: more like fertiliser than mulch.

But anyone moving into a new house usually has to start from more scratch than me, because at least I had trees, shrubs and weeds, whereas a new house is generally surrounded by bare dirt; if you’re lucky, the topsoil has been carefully scraped aside and stockpiled for later.

Twenty six years ago, I scrounged compost and mulch from farms, bought numerous bales of pea straw, raked leaves from up and down the street, and snaffled a pile of ancient forgotten Electricity Trust mulch from a farm paddock. I hired a mulcher for prunings; virtually no organic matter from the kitchen or the garden left the property, and soon the orange clay on the cut and fill site around the house turned a rich, friable dark brown.

In the months I was removing the blackberries last year, I’d already started barrowing lawn clippings, compost and leaves from the old garden into the new area, but the real bargain came in early spring. Well, not really.

The trees under the power lines in all the suburbs around me are pruned annually in early spring, and this year was no exception.  I stopped beside the pruner’s truck and asked, could I buy a load of mulch, and for how much?

“No worries, luv, it’s fifty bucks or a slab of beer.”

Well, that seemed reasonable, so I dropped off a slab of Coopers and the foreman told me he’d deliver the mulch in the next hour or two. “It’s a good load, all eucalypt and no pine,” he said, and added something about x cubic metres. I didn’t really listen – any amount was fine by me. I was burning the blackberries that day so left instructions as to where I needed the mulch dropped out the front, as I wouldn’t be able to leave the fire.

I heard the truck arrive and, when the fire was out, checked my delivery.

Crikey! I was gobsmacked to see there was not five or six but TWELVE cubic metres heaped on the verge, spilling out across the street as well! Twelve cubic metres is a LOT to move! And I had to move it a LONG way: sixty metres to a spot on the new block, one barrow at a time, up steps and around corners. But wow, what a fantastic bargain! Twelve cubic metres for fifty bucks! I felt very pleased with myself for saving so much money, though this feeling turned out to be premature.

My HUGE pile of mulch waiting to be moved

I grabbed the barrow and started immediately: I wanted to clear at least the roadway before dark. After three hours with a shovel, I looked at the pile. For the life of me it appeared no different to when I’d started: I hadn’t even made a dent! And I was exhausted already!

I needed better tools. The shovel wasn’t working: half of every scoop slid off between pile and wheelbarrow. I needed a proper mulch fork – one of those wide, square ones with about ten tines and a short handle. I rang around – hardware stores, garden centres and nurseries couldn’t help, but  a nearby fodder store had one. Excellent! I raced down and yes, it was exactly what I was looking for.
I took it to the counter and the proprietor checked the price and frowned, and had the grace to look a little embarrassed. “Ahhh, it’s quite expensive: $259.”

Quite expensive?!? Two hundred and sixty bucks?!? He was joking, right? Or there was a mistake, perhaps that price was for the solid platinum model? But no, he wasn’t and it wasn’t. And none of the dozen places I’d rung earlier had any alternatives. It was this one or nothing.

My expensive but very effective mulch fork

There went my bargain. I glared at the pitchfork for a long time. I could certainly get one at a fraction of the price online, but that could be weeks away, and I needed the fork now.  I thought about the 11.7 cubic metres still remaining out the front. That would be joined the following day by an additional eight or nine cubic metres of mulch when the arborists came and felled the pines on the block; their mulcher would be parked out the front too. That  made a total of twenty cubic metres to shift to a pile in the new area, and it would have to be shifted again onto paths or garden beds. That made forty cubic metres to shift, one forkful at a time. .

I bought the bloody fork, thinking it had better darn well be worth it.

Was it? Well, two months down the track, I have to say, yes, it was, not least because I‘ll buy more mulch next spring.  It’s exactly the right tool for the job; it takes 5 or six scoops to fill a barrow instead of a dozen or more with the shovel, halving the time and significantly reducing effort. If you have a friend who owns one, borrow it and buy them a very nice bottle of wine or carton of beer for the privilege!

So what am I doing with all that mulch?

Initially, I’d intended to spread it conventionally but, although it’s ideal for suppressing weeds, it’s really too fine for conserving moisture. When mulch is this fine, it acts like a sponge and the light showers that fall in our Adelaide summers never get a chance to reach the soil; overhead watering, unless very heavy, meets the same fate. It can actually be counterproductive, because instead of sending their roots down deep in search of water, plants concentrate their roots on the surface in the mulch, and the first hot spell wilts them.

I much prefer open, coarse mulch like pea straw, teased out rather than placed in dense biscuits. The pea straw doesn’t break down much during our dry summers, but over autumn and winter the extra moisture rots them so that the worms incorporate them into the soil, ready for a fresh layer next season. Everyone has their preference for timing of spreading mulch, depending on their microclimate and their priorities – to conserve moisture, suppress weeds or  to nourish the soil. I prefer spreading pea straw in early summer rather than early spring, so seeding plants in my garden have a chance to germinate. But once the new garden is established with vegies, I’ll probably do it earlier.

So I have twelve cubic metres of mulch. That volume is enough to landscape with, to recontour and to build raised beds. I decided I’d use the mulch as soil to backfill terraces. I first scatter generous amounts of gypsum over the bare soil behind the retaining walls and areas I’ve dug over.

Lucerne straw is a very effective, chunky mulch

Then, where more “soil” is needed to raise the height, I barrow the mulch, sometimes to a depth of 60 centimetres. At the same time, I scatter pelletised chicken manure – Rapid Raiser or Dynamic Lifter – to add nitrogen and help worms create friable compost. If the mulch is dry, I sprinkle it with water to speed things up. The mulch is still too fresh to plant into but, by the time I put in my first trees in winter, the worms and soil microflora and fauna should have done their job. I’ll check the pH and water-holding characteristics before planting, too: sometimes compost like this becomes hydrophobic (water-repellent) if it dries out, and requires additives to prevent it shedding water. Or I can simply dig it through so the soil below is incorporated.

To lower the temperature and encourage worms to come to the surface, I’m also mulching with a layer of pea straw or lucerne.

However, I’m not using the pine mulch to create new soil. Pine needles are quite acidic – often a bonus on Adelaide’s alkaline soils – but many of them also contain allelopathic chemicals. These chemicals inhibit the germination of other plants – just envisage the ground under a pine plantation and you’ll have an idea of the chemicals’ effectiveness. This is great if you want to suppress weeds, but definitely not so good for a vegie garden! The effect declines over time, but I’m using all the pine mulch on the paths, where any allelopathic action is most helpful.

It’s incredibly tempting to plant into all these fallow beds, but there’s no point. Vegies won’t thrive in raw mulch, so for now I have to be content just to imagine… and to plan!