FALLEN leaves are an invaluable resource for gardeners. I can’t collect enough and find endless ways of using them to enhance the soil. But be aware that some collecting methods could damage micro organisms and the habitats for some small garden residents.

I never underestimate the value of these tiny creatures. They play a vital role in breaking down fallen leaves, like the the ones we’ve collected. But leafmould adds little nutrient. Before deciduous trees shed leaves, they extract a leaf’s remaining nutrients such as nitrogen and phosphorous.

However adding leafmould gradually improves soil structure, letting it absorb and retain moisture more efficiently. Astonishingly this is even beginning to matter in Scotland, given the long dry spells caused by climate change. This improved ground lets plants grow more strongly.

As with all other composting, in making leafmould we gardeners use a perfectly natural process to improve our ground. We just need to make sure we don’t accidentally cause any environmental damage.

The lawn must be cleared of leaves: they look unsightly and smother the grass. Predictably, these leaves are also welcome shelter for small invertebrates, so remove leaves promptly before small creatures move in.

I go over the grass several times but still have to face the environmental question: do I sweep up the leaves with the noisy, fuel-guzzling lawnmower or use a tine rake? If I had a small lawn, I’d certainly use the rake, but with my large area of grass, I’d be devoting every daylight hour to it. We all have to choose: for me, frequent mowing = a sane compromise.

Hard surfaces are a different matter. Again, leaves must go to avoid a slimy, unsightly mess. Leaf blowers are the mechanical equivalent to mowers, but are much more damaging. Each leaf is sucked up and chopped into tiny pieces, killing the organisms sheltering on it.

And the German government has just urged gardeners not to use leaf blowers because of their potential damage to insects. This is all part of that government’s programme to help mitigate the global collapse in insect numbers.

Of course, collecting leaves from gravel paths is challenging and using a blower to sweep them on to a hard surface may be necessary, but you would reduce damage by then brushing up the piles of leaves; using them to make leafmould.

Flower beds can be treated differently. You may need to brush fallen leaves off plants, clearing stems and crowns. But leaves are mulching for any bare soil between flowers and shrubs. They look perfectly natural and as the leaves gradually rot down they improve a bed’s structure and biodiversity.

I’ve got a poor bed at the bottom of the garden. Excavations to instal a septic tank many years ago threw up clay which weathers very slowly indeed. Fortunately the bed is fairly close to an elm tree so its natural largesse is very slowly working its magic.

So, supplement this natural harvest by constructing a special leafmould bay with wood or rabbit netting or use a leafmould bag.

Compostable bags are available, but, not having used them, I can’t comment on how well they work. You may find these bags dry out round the edges preventing leaves from breaking down. Give the bag an occasional soak if necessary.

You could use a stout plastic bag, pierced with lots of holes, leaving the top open to collect rainwater. The top layer may dry out, but the plastic should keep the inner leaves moist and allow them to compost well.

This takes about 18 months, but oak and, beech take another year because of their high tannin content.

Plant of the week

Blueberry ‘Rubel’. The leaves turn brightest fire red in the autumn warming the dreichest of days. The berries are particularly tasty and said to have an extra high antioxidant level.