Drowning in leaves
A heavy blanket, hiding slugs and smothering everything beneath it
Our garden sits beneath one of the biggest oak trees I have ever seen. Every year, come October, we begin to garden under a steady drizzle of leaves, and by mid-November we face a deluge. We have been inundated in the last few weeks and they are driving me crazy. Small enough that they slip through the tines of a rake, they form a dense, dank mat that smothers everything growing beneath it. They tangle themselves into the crowns of plants and have to be combed out by hand, one by one. Arthur has been giving me a hand with his wheelbarrow, but the temptation to throw them lies heavy on him, and our gardening sessions often end as frostily as these November mornings begin.
Having painstakingly gathered buckets and buckets of them, I’m left with the question of what to do with them all. First off, in order to reduce the wildly unmanageable volume, and speed things up a bit, I chopped them up by mowing over them. Unfortunately, my mower is about as dodgy as you can find (left to us by the garden’s previous owner) and in 5 minutes I had successfully redistributed around the garden what it had taken me 5 days to collect. Still, it was quite fun while it lasted and the product (once I had scooped it off every surface within a mile radius) looked satisfyingly ‘professional’.
The very first leaves to fall were swept into the compost heap where they act as a ready carbon source to balance out end of season Nitrogen from cutting back, weeding, a last mow of the lawn, and my growing hibernal coffee habit. But as the drifts deepen I’m reluctant to throw them all on the heap for several reasons.
Some leaves litter isn’t so bad… these are scattered underneath my Acer…
First, we just can’t compost that volume. A compost heap needs a fine balance of Carbon to Nitrogen and, no matter how many flat whites I make myself after a sleepless night feeding Laurie, no matter how many veg scraps we throw out, we just won’t produce enough ‘green’ waste to balance so much brown.
Second, oak leaves (and most other dead leaves) aren’t the ideal composting material. Not only can they clot together and smother the heap, they also break down incredibly slowly. Oak leaves are full of tannins which, in high concentrations, can inhibit the action of some microorganisms in a compost heap. This won’t stop the rest of the heap from breaking down, but it does seriously slow the process when what we want is a compost heap that acts quickly. Untreated cardboard and brown paper are a much easier option for compostable carbon and also hold the texture of the heap open rather than gluing it together.
There’s also a lot of talk about the acidity of oak leaves, but this is less of a concern. Theoretically the acidity could slow the composting process, but mostly people seem nervous that using oak leaves could lower the pH (increase the acidity) of their soil. In fact, the soil beneath mature oak tress has been found to vary widely in pH, based on the underlying soil type, and it isn’t really possible to adjust soil pH with a mulch long term, so on this point at least, I can set my mind at ease.
Fungal action already visible on the leaves before I gather them
So, what to do with them? I’ve seen them recommended as a mulch in their raw, undecomposed state, chopped up so they allow air and rain to penetrate, and then applied thickly over the soil, but this doesn’t appeal and I’m not ready for mulching yet anyway.
This year, I have gathered them up into bags to become leaf mould. The leaves are broken down slowly by fungi rather than the quick, hot action of bacteria. The process may take a while (about 2 years), but the result should be a rich and dark resource for the garden. Having stuffed the damp leaves into bags, I have bundled them away to lie forgotten, working their slow magic. Any acidity and toxicity from the tannins (and the juglone in my walnut leaves) will gradually fade away as they decompose and in 2 years, with any luck, I will unearth a magical, musky prize. Leaf mould is light and low in nutrients, qualities that make it a great addition to homemade potting compost. It’s also a great soil improver, helping to bind with clay and open it out, but inversely containing lignin which holds nutrients in light sandy soils. Now, with the hard work over and a garden free of leaves, all I have to do is be patient!
