Alys Fowler: Leaf mould

Near my school was a deep ravine covered along its ridges by beech trees. It was a great illicit spot, though I liked lying there not to consume cigarettes and alcohol, but to watch the autumn leaves fall. You could lie back and watch them tumble, and beneath you was a bed of the thousands that had tumbled before them. You could reach down into this cool mattress and under your fingernails would be dark black stuff – leaf mould.

This stuff is amazing. It's been described as nature's substitute for peat. Like peat, it is a soft, inviting medium for plant roots. It's kind to seedlings and a great place for them to start life. For older plants it will seal in the moisture and, if spread thickly enough, will suppress weeds as a mulch. It will take heavy soil and make it light again. The worms love it and so should you, because it's free and easy to make. Simply gather the leaves and wait.

The drawback is time. Good leaf mould is a bit like vintage port — year one is fine for mulching (particularly around woodland plants), but year three is much better. A vintage mould is dark, crumbly and smells sweet. This is the stuff for seed compost (made from equal parts leaf mould and sand).

Autumn leaves take a long time to rot because they go down the fungal route, rather than the bacterial one that your home compost uses. To work efficiently, bacteria needs moisture and a lot of nitrogen, two things autumn leaves lack. The simplest way to make leaf mould is to gather the leaves into black bin bags with holes punched in the sides. Leaf mould takes an extra long time if it's too dry, so gather the leaves after the rain. The bin bag method is successful because it holds in extra moisture.

If you want to make more, create a wire bin with four posts and line with cardboard. Heap the leaves so that they have a flat top to catch rain. Discard any dead branches and never include weeds. The heap will drop considerably in size, so collect more leaves than the bin can hold. Never include infected leaves.

If all that waiting is just too much, there are tricks to hurry things along. Mowing the leaves before you pile them up hastens the process. Spread the leaves out on the lawn, take the collection box off the mower (they'll just clog everything up) and mow away, rake up and heap on. But to truly speed things up, you need to get hold of some nitrogen, and the best source, at least the cheapest and most environmentally friendly, is your pee. If you take this route, I advise you site your bin somewhere sensible.

Alys on... Forcing rhubarb

You can divide rhubarb both now and again in spring. Lift the plant and split it into decent-sized pieces, each with a crown (where the new growth will appear). You should not harvest from these young plants for the first year, so they can establish a good root system. Replant with lots of compost and mulch again in spring – all those huge leaves need lots of food.

If you have a giant that has been sitting around for years, you could force fresh rhubarb for Christmas. You'll need a large container with holes in the bottom, somewhere frost free, and, of course, rhubarb. Dig up some good-sized crowns and pack them tightly into the container with moist compost. In a warm greenhouse you'll have fresh shoots in about four weeks; cooler conditions will take about eight weeks. Exclude light for very tender stalks by placing a bucket or cardboard box on top. Once you've harvested, plant the crown out in spring and don't pick or force again for at least another year.