Composting: the shortcuts that make a difference (and what to do with citrus skins)
If I ever tell you I am going away for three weeks in June again, please confiscate my passport immediately. As I hugged huge trees in the temperate rainforest of the west coast of Canada (see above), back in my garden in the UK, whole empires of aphids rose and fell, tomato sideshoots sprawled and succumbed to blight, and roses melted in the rain.
What didn't suffer in my absence was my compost heaps. They did just fine: the heat of summer brought the temperature up nicely, and a capping of cardboard and old bath towels on the heaps ensured that they stayed moist. That's what I love about composting, its not an exact science, and your heap will forgive you if you neglect it for a few days, weeks, or even months.
And yet ... I've been looking back at a chapter about composting I wrote for my book on allotments, published back in 2008, to see whether anything has changed in my approach during the intervening years. Not much: I stand by my opening line, "An allotment without a compost heap is like a car without an engine: going nowhere."
But I would quibble with my past self over one matter: whether it's worth the time and effort to chop up plant stems and fruit and veg into small pieces before adding to the compost. At the time, I thought it wasn't. But a greater understanding of soil science (in great part due to the wonderful book Teaming with Microbes by Jeff Lowenfels - listen to the composting episode of Sow, Grow, Repeat for an interview with Jeff) and a tip from Toby Buckland made me realise that chopping up the ingredients for the compost is worth it, and it doesn't have to take forever, either.
I can't remember where - maybe it was on Gardeners' World - but Buckland was showing how even putting a cut or two in a really thick brassica stem - the kind that's as thick as your wrist and likely to resist even the sturdiest shredding machine - helped to increase the surface area for microorganisms to get to work breaking down the organic material into humus. Since then I've been doing just that - and getting stabby with melon, grapefruit and avocado skins (perfect therapy for processing the latest cabinet reshuffle news) too. I'm assuming it works from the fact that I've yet to find any big lumps of said skins in my "finished" compost since I started this approach. I wonder, if you happened to have an old food processor, whether you could whizz kitchen waste up in that before applying to the heap to speed things up yet further.
Citrus skins can be a problem in wormeries and to a lesser extent compost bins if, as in my household, you get through quite a few. Here are three alternative things you can do with citrus skins:
1. Turn them into firelighters.
This was a trick I learned off the wonderful Jack Monroe's Instagram feed. If you have halved lemons left over after they've been tested and juiced, stick them in an old baking tray in the bottom of the oven when you next use it until they turn black and hard - then use them just as you would firelighters, either in a fireplace or on a barbecue. I haven't tried it with other citrus but can't see why they wouldn't work just as well.
2. Use them as slug traps.
A grapefruit half placed cut-side down can be a great slug lure - in the morning, pick them up and dispose of your catch however you see fit. I have found this works best on moist soil.
3. Mulch acid-loving plants with them.
I have never heard or seen anyone else do this, but I place grapefruit skins on top of the compost around my potted blueberries, on the basis that they will appreciate any raise in acidity they bring, and also help to keep the soil moist - crucial for good fruiting. Top with a further layer of spent compost if you find fruit flies become a problem.
Or just add them to your compost heap, following my advice above about cutting into them a bit.
Now, people get all overheated about this, but it's mostly not a problem to add citrus to the heap. If you have a juicer and are getting through a dozen fruits a day, maybe yes it's an issue, but otherwise, provided you balance it up with other non-acidic stuff, citrus is not usually a problem. The local mice have found it makes a fabulous nest for their babies, which was, I admit, super-cute.