From food waste to fertiliser

Ever wondered what kitchen scraps you can and can’t put on your home compost heap? March’s gardening column tracks the final link in the food waste chain.


No Time to Waste. This article is part of a joint campaign by Riverford and Wicked Leeks to help people cut food waste and raise awareness.

Today I’m talking about gold, black gold.  A little bit of garden alchemy.

Yes, it’s time to think about compost. If you already have a heap, you’ll be spreading this dark, rich, crumbly stuff on your beds – preparing the soil for that Spring rush of growth. 

The alchemy comes from turning waste into gold. Mix all those grass cuttings and veg peelings, with unwanted paper and cardboard, and let the magic begin. Worms, beetles, springtails, bacteria, fungi all play their part in munching down the organic waste and converting it to black gold. If you want to know more about composting at home, visit Garden Organic’s composting page here.

But today’s cooks keep their carrots and potato skins on, as we now know that the skin helps contain the essential vitamins within during cooking. So what else can you put on your heap? And what if you don’t have room for a heap or two?

Using scraps and trimmings in your compost heap transforms their nutrients for use the your garden. Image Edward Howell.

First, the microscopic life in compost is hungry for nearly all organic i.e. plant-based material. As well as the kitchen inedibles (tea leaves, coffee grounds, egg shells, citrus peel – even pineapple leaves and avocado skins) you can add weed foliage, mashed up prunings, straw, plus ripped up cardboard (non plastic-coated) and scrumpled up paper. 

My little worms get to read my paper credit card statement along with the bags of junk mail, all torn up and stirred into the mix! I keep the balance of ‘greens’ and ‘browns’ at about 50:50, adding water when things look a little dry. Just don’t throw in dairy, cooked food or meat products. You’ll be attracting vermin. And don’t put weed roots or seeds in; they will only come back with a vengeance later.

A wormery is a good option for smaller spaces to use up food waste. Image Sippakorn Yamkasikorn. 

If you don’t have room for a heap, then why not try making or buying yourself a wormery?  This is a plastic box system, which fits in a corner of the kitchen or on the patio. Inside are worms, which are fed by your food waste. As they quietly chomp, the worms digest and excrete a rich compost that leaches a powerful liquid fertiliser, all inside the box.  This is liquid gold.

The worms are pretty omnivorous, so – unlike your outside compost heap – you can add nearly all your leftover food, cooked and uncooked. Although they don’t like too much acid from citrus fruit peelings. Owners of wormeries think of their inhabitants as pets. Carefully feeding them, keeping them warm and moist. And, before you ask, no, they don’t smell!

How do you use your compost?

Now is the time to spread a layer on your veg beds and round any perennials. Make up your own potting compost mix, sieving it with some soil and maybe some grit. Feed hungry plants in pots with a top dressing, lightly forked over.

The soil is coming to life, feed it, put it in good heart, and your plants will grow. The cycle of life is complete.  And the magic of natural processes begins again.


Leave a Reply

  1. I’m a committed composter with 2 big compost bins in my garden and 2 on my allotment. I agree with everything in this article, thanks! I just wanted to warn those new to the black art that it’s not always as straightforward and romantic as it’s sometimes portrayed. For example the language of “this dark, rich, crumbly stuff” makes it sound very clean and tidy-perfect homogeneous compost every time- whereas the reality in my experience is messy and untidy, and often incomplete, most of the time. I’m sure perfect compost is attainable, and people you, Garden Organic and Monty Don are right to encourage it, but newcomers should I think be warned that living with imperfection inevitably comes with the territory!

  2. Hi NickPlant, you are absolutely right! There is no exact science to composting, which would result in anything clean and tidy. Unlike the bags of stuff you can buy, home-made compost is wonderfully bulky, and full of variety in its constituent parts. Thanks for pointing that out.
    And perhaps another thing I should have said, was “Be patient”. It takes from 6 – 12 months for an open heap to rot down, depending on ambient temperature. Turning the heap thereby aerating it helps speed the process.
    But at the end of the day, home composting not only turns waste into fantastic fertiliser, but also reduces landfill.. A win win.


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