Garden School:


Garden School:
Teaching this week: Rose pruning (as always!) and leaf mold.

Friday, 11 November 2011

Time to make leaf mould!

Yes, it's that time again: I spent a happy hour yesterday raking up leaves and stacking them in the Leaf Mould bins for a client. 

I'm into compost and leaf mould in a big way, I even lecture on the subject, (If you want me to come and give a talk at your organisation, just email me - but only if you are near to Wantage!) so it's lovely to be paid for doing it!

In case you're not totally clear on the subject, here's the briefest precis:

Garden debris rots as an aerobic process, meaning that it needs oxygen. Hence the presence of worms, earwigs, and other livestock in your compost heap.

Leaves rot via an anaerobic process, meaning without oxygen - they use fungus. Hence there are no worms, earwigs or other livestock in the leaf mould bins, just fungus.  It also take a lot longer - two years, normally.

If you don't have many leaves, it's ok to put them on the compost heap, if you mix them in well - they will eventually rot. Even better if you can shred them, or mow them up.

But if you have a lot, it's much better to treat them separately. You can either make special leaf-mould bins out of chickenwire, or you can simply stuff them into black plastic sacks and stack them out of sight somewhere.  (Black bags are not the prettiest part of gardening.)

Honestly! It works just as well in bags, but if you have a lot of them - and most of my clients have big gardens and lots of trees - then making chickenwire bins is much quicker and easier.

The only "trick of the trade" (if you can call it that ) is to make sure the leaves are wet.

The resultant leaf mould is wonderful stuff for conditioning the soil - it doesn't have a great deal of nutrients in it, unlike proper compost, but it lightens the soil and helps it to hold water. And it's completely free! All you have to do is collect the leaves, leave them for two years, then spread it around...

...and as I like to be helpful,  here are my Top Tips:

A - Leaf Mould bins/pens

1) Leaves are not heavy, so you literally only need chicken wire wrapped around four posts.
2) They are, however, very bulky, so you may need to make three or four of them.
3) Make sure they are wet - frosty days are ideal for raking up the leaves. If not, just water them. This also helps reduce their bulk so you can stuff more in on top. If you site them under trees, you may have to add more water a couple of times during the year.
4) Next year, you could shift the half-processed stuff from three bins into one, to free up a couple more bins - but that is making work for yourself. Do it the easy way, make plenty of pens, let them sit for two years.

B - Leaf Mould In Bags

1) Rake up the leaves, stuff them into plastic sacks. The bigger the better.
2) Throw in a bucket of water, make sure they are good and wet. You want them to go mouldy.
3) Tie the top of the bag, loosely, then stab the sides viciously with a fork. We are aiming for wet, not sodden. If you don't tie the top, and stab too enthusiastically,  they all come flying out of the top of the bag. Ask me how I know this......
4) Stack the bags out of sight somewhere. Behind a shed is ideal.
5) In two years' time, they will have shrunk into flattened slabs. Open, or peel off the bags, if you used thin bin-liners. Good quality bags can be re-used. Break up the slab of dark, peaty stuff and there you go.

C - General Points

1) Don't attempt this with evergreen leaves - holly, laurel, conifers - as it won't work.
2) Don't bother with Horse-Chestnut leaves either, they don't rot well.
3) Other than those, yes, you can mix up as many different types of leaves as you can.
4) No, you don't need to shred the leaves.
5) This is for leaves only - don't mix in grass cuttings, or normal garden waste.

I've often read on the internet that leaf mould is a good potting compost, but I'm not convinced about that, as it is pretty low in nutrients. I would say that it makes good seed compost, as it does not contain weed seeds, as long as you pot the seedlings on into "normal" compost or bought compost.

Anyway, there are the basics, so off you go! Rush outside with a rake and make yourself some free leaf mould.

As far as I know, there is nothing to stop you raking up leaves from public areas such as parks, grass verges and footpaths, so if you have room to stack the bags, but no trees, this need not stop you!

Thinking about it, it would be lovely if we could start some community schemes - I live on a housing estate which a huge number of grassy areas and a good variety of trees, and there are leaves everywhere. If only the local brats weren't so bratty, I would make some pens and encourage my neighbours to help to fill them, and to help themselves to the leaf mould in due course. But - sigh - I just know that the pens would be pulled apart, or the leaves would be set on fire.

Oh well, maybe one day...

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