THE BEST LEAVES TO SUPERCHARGE SOIL
Use autumn leaves to supercharge garden soil.
TREES ARE MINERAL-GATHERING machines. Their roots draw calcium, phosphorus, magnesium, and potassium from the soil, which is transferred through the trunk to the branches and leaves. As the leaves change colour and prepare to fall, some of that goodness returns to the tree. The rest remains in the leaf until it touches the ground and is recycled back into the soil via fungi and microbes. Newly fallen autumn leaves are more mineral-rich than manure and a valuable resource for food gardens. They make nourishing mulch, are useful as the dry component of a compost heap and, with a bit of patience, can be turned into leaf mould. The most minerally rich leaves are the ones that have recently fallen to the ground.
SLOW + FAST
Some leaves break down rapidly, and others take forever. The difference is the amount of lignin in each type of leaf. Lignin is a chemical compound that keeps plants rigid - think of it as an organic form of Polyfilla. Leaves with more lignin (oak or birch) don’t compost as effectively as those with less (maple or poplar). Thin, easy-to-crush leaves are generally low in lignin and a good choice for the garden.
WHEN TO LEAVE IT
Fallen fruit and nut-tree leaves are best left in situ. They have a lovely mineral balance, are low in lignin, and break down easily to provide onsite nourishment for the plant for the next season. Removing leaves only to add some other form of fertiliser is extra work for no reward. Ornamental trees don’t require as much nutrition as fruit trees. Forage some of the fallen leaves but leave half behind for the tree.
COLLECTION ZONES
Get to know neighbourhood trees and forage for leaves in public parks. There are plenty of people with large deciduous trees who appreciate someone coming and collecting them.
SHRED IT
When using leaves to make compost, mulch, or leaf mould (see page 31), the first step is to shred the leaves. Run over
them with the mower a few times, put them through a shredder, or get a gang of jumping children on the job. Keep shredded leaves somewhere dry and dark until ready to use.
WONDERFUL LEAF MOULD
Leaf mould is that beautiful, soft, dark stuff beneath the twigs and leaves on a forest floor. Leaf mould is made of brokendown leaf litter and twigs, and it’s teeming with microbes. It’s the perfect addition to homemade seed-raising mix, a lovely, peaty material that’s great for new roots because it warms up well and holds moisture. While it’s super-easy to put together, it can take up to two years to break down, depending on climate and the type of leaves.
LEAF MULCH
A mix of shredded leaves makes a beautiful, life-giving mulch for vegetables, herbs, flowers, and berries. Leaves attract microbes and worms in droves, which break down, consume, and incorporate them into the soil humus, helping a garden to thrive.
LIFE BELOW GROUND
The soil beneath plants or mulch is home to millions of subterranean life forms, including beneficial fungi, bacteria, nematodes (roundworms), and worms. Bare soil is labour intensive because inevitably, the space will fill back up - hello weeds. These fast-growing, hardy plants are perfect for the job of quickly covering the ground and are part of nature’s cunning plan to keep soil healthy. Microbes are attracted to plants. In 2018, scientists at Rutgers University discovered that plants ‘farm’ microbes by secreting sugars, proteins, and vitamins around root tips. Microbes are trapped in the plant cells, then broken down by the plant to become nutrients. Surviving microbes help the plant produce more root hairs. This symbiotic relationship encourages the plant to grow taller, and roots to grow deeper. More significant root systems provide more opportunities for additional microbes. The broader the range of plants growing above ground, the more extensive the range of microbes. Microbes improve photosynthesis, convert and distribute minerals, protect plants from pests and disease, build humus and, importantly for the planet, capture carbon. It sounds simple, but it’s that easy. Tap into these powerful networks by keeping soil covered. ■