Garden Woodworking

Compost Fettling

Spring and Summer in lockdown. What to do?

There are always things going on out in the garden. I should use the time to do some tidying up, and fettling of the various things that tend to decay over winter.

Specifically; the compost bins. I built these many years ago. Four bins in all; two for rotten veg, weeds, etc, and two for grass cuttings. Alongside, I set an area for bags of leaf mould. Basically, the corner behind the big Cedar tree is a place where things can deteriorate. The hard part is stopping the bins themselves from deteriorating.

I made the bins by embedding treated fence posts in the ground using Post-Fix. Then I scavenged for pallet wood, gravel board, and other scrap that looked like it would last a few years outdoors. I used deck screws to fix boards to the posts on three sides each, to make a series of U-shaped containers. I then screwed wood strips to the front posts, producing slots into which I could slide planks to build up each box. I figured that making the front pieces removable would make turning the heaps over and emptying them much easier.

And would you believe it? I found a PowerPoint sketch I made of the original plan!

I originally thought of marking the bins out by drawing two big circles and putting posts at even spaces around the arc. When I began construction I realised I had a number of 2.4m long planks which were perfectly good as they were. There was little point in cutting them just for the sake of the shape. So I adapted and went with two straight lines at the back. (This also meant I could switch two of the back pillars from circular to rectangular, using up an old fence post and saving the round pillars for future use i.e. the repairs that would be needed 15 years later!)

No photos of the original work though. Sorry! I guess I was too worried about getting that new fangled digital camera mucky. I’m less worried about my phone these days. Priorities, eh?

The bins lasted very well. Some planks were replaced from time to time, but it was easy to unscrew the old and slot in something new. And so they stood for 15 years. A fair investment I think.

Of course, the main weak point in the bins would be the posts. 15 years in the ground is generally the limit for a wooden pillar, and these had the added problem of a concentration of insects, worms, nematodes, bacteria and other things whose duty is to break down organic matter. This year, it was time to swap out the posts and give the bins an overhaul.

Given the loss of wood availability due to lockdown, I had fortunately pre-empted this work. Last autumn, when I needed to repair the leg of the swing on The Den, I also bought a selection of fence posts and a few sacks of Post Fix on the presumption of doing this work sometime soon. I then took a tour around our and various neighbours’ gardens (with their permission!) seeking out bits of scrap that could possibly be re-purposed. Here’s some old decking that looks ideal for this new use:

While I think of it, here’s a quick tip: If you want to saw a rough piece of wood leaving a square end, you can use your saw as a set-square. The outside line of the handle should be set at 90 degrees to the top of the saw blade (the saw above gives me both 90° and 45°.) So, if you lay your saw across the wood to be cut, with the handle pushed up to the wood edge, you’ll get a nice square line to mark up and saw along.

I worked one or two posts at a time, spreading the work over several weekends. For each post, the first thing to do was to shift any remaining compost and soil, and clear the work area down to the concrete. Then I could take away the attached planks and wood strips, and see whether the post would lift out of the hole, or would need to be drilled out.

Next step was to look at the concrete and decide how to fit the new pillars. The new pillars were a smaller diameter than the originals, and so in theory would slide into any holes left in the concrete. This was tempting but, in the end, I chose not to do this. I was concerned about how easy it would be for water to funnel into the gap. Water would bring creatures to attack the wood. I felt a good close bond between wood and concrete would be best.

So, I opted to take my impact drill to the concrete and break it up, using the rubble as ballast around the new pillars, with fresh post-fix to secure the whole lot together. I would also bring the concrete up to a higher level around the pillar, then cap it with a ring of gravel. I was aiming for maximum drainage in the area of the wood and minimising the amount of soil the post would be in contact with.

Before anything went near the plot, it was given a thorough coating of Wood Preserve. I’ve found over time that you can get wood stains, and wood preserves, and they’re not the same. I go for a preserve that is applied in 2-3 coats, with plenty of drying time between. Rather than just sitting on the surface, this stuff will penetrate deep into the wood, making it intolerable for wood-eating creatures. I don’t need elegance or colour consistency in these bins, I need them to hold off the rot for a decade or more.

So, with new posts in place, I could restore or replace the wood panels forming the bins. Much fettling, refashioning and preserving later, the bins gradually remerged.

I mentioned earlier about fitting strips of wood to the front posts so that planks could be inserted and removed easily. Here’s an example of this, that also shows how I coped with the post being circular.

The curve of the post meant that the edges of strips would’ve diverged from each other, reducing their ability to hold the plank. I countered this by running a jigsaw down the length of the wood strip with the blade set at 30 degrees, to saw off a triangle from the edge. Then, when two strips are screwed in place, it the two sawn edges create a tighter slot for the planks to sit in.

Jobs like this always feel somewhat fruitless, especially when the rest of the interaction with the bins is not that pleasant – we pile up rotten veg on the heap, and every now and then get busy with a fork to turn it over. Eventually, we shovel it out into a wheelbarrow to throw on the borders and veg patch. Grass cuttings are particularly hard work, mainly because there’s such a lot of it. We have a big lawn that produces too much grass to mix in with the food waste – it would turn the compost all sloppy if it wasn’t treated separately. I found a composting method for grass in which you keep it as dry as possible and don’t turn it. Instead layer it with soil and fibre (I use egg boxes and loo rolls, mainly) and cover to keep the heat in and rain out. The soil adds back the nematodes and things to help break it down, and the fibre gives them something to mix in to give it a firmer structure. It takes a couple of years to properly break down, which explains the size of the bins – I have the grass ones full to overflowing by the autumn – but it produces a very rich, thick compost that seems to go down well around the plants in the borders.

Anyway, at the end of it all we get good tasting veg, we have a nice clean lawn and borders, and we don’t throw much stuff away. So all in all, investing a few afternoons in keeping these bins fettled seems to be a good thing. Lets see if I still think that in 15 years time…

By nickcnickcnickc

I spend my working life staring at computer screens, so in my spare time I look for things to do with my hands, preferably involving wood. It's a little ironic then that I've now starting writing a blog about my woodworking, and thus introducing computer screens to my main hobby..!

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