The best plant food that money can’t buy

When autumn arrives, the garden plants slow their productive summer pace and prepare for the cool weather ahead. Rose hips ripen and tell their plump sticks to harden before the frost arrives. Flowers fade and the foliage turn brown, drawing the harvested nutrients from the buds and bloom back into the roots for perennials to bridge through into spring. The same applies to deciduous trees, whose nutrient-rich autumn leaves are specially tailored to the needs of the shedding tree.

Hence, the best plant food that cannot be bought comes from deep mulching of fallen leaves.

Serious? Yup. When leaves are just too messy to drop leaves where they want, run a mulching mower over them or shred them. Now pile the fluffy pieces in generous piles under trees, around shrubs and all over beds and borders, ornamental and edible alike. Moisturize them well so that they are less likely to blow away in winter winds, or cover them with bird nets weighed down with stones to keep your mulch exactly where you want it.

Where you don’t want it is over lovely patches of moss that you might appreciate. Moss gardens are not improved by a deep layer of leaves, so use more bird nets. Spread out on a moss-covered carpet, the net can be rolled up every few days, and the leaves can be shaken out over vegetable patches or the compost heap. Deep leaf mulches are ideal for areas where you are expanding a bed or border, or planning to expand a pollinator field. Moisten the bare soil, then pile up the leaves and moisten each 2-4 inches of layer. This keeps them in place and also speeds their decomposition. So in the spring you will find beautiful, open soil ready for planting.

Several people have asked if “bad dirt” should be dug up and thrown away. Unless something really bad is going on with the floor, we’re much better off fixing it than throwing it away. Here, too, leaves come to the rescue, adding their accumulated nutrients as well as the humus released during composting. However, if soil has been removed from a site, you are likely working with subsoil rather than natural topsoil. In a situation like this, you can certainly bring in a composite topsoil mix, but I would sprinkle humic acid granules over the subsoil before adding the topsoil mix. If I were lucky enough to have a lot of leaves I would also add a leafy top mulch as our marine soils are usually quite poor in humus.

Soil that is simply starved or exhausted from overuse is best cured by layering it on top of compost annually with a 1-inch top dressing of wood chips (not bark!). The wood chips help maintain soil moisture, resist erosion, and keep many weed seeds from germinating. Every spring, put more compost right over the now-composted wood chips and renew the chip-top dressing as well. Add another 4-6 inches of leaves each fall, filled with a whole range of phytonutrients, from carbon and carbohydrates to phosphorus and potassium. Year after year, these autumn leaves will hold the soil in what farmers call “good heart”, which means fertile and well-drained. By the spring, the deep leaf mulch will have crumbled into a 2 or 3 inch layer. To sow or plant, expose the bare earth for each planting hole, then put the plants in the mulch. Over time, soil that is mulched annually and treated with top dressing can support tighter than usual planting while also requiring less water in the summer.

Contact Ann Lovejoy at 413 Madrona Way NE, Bainbridge Island, WA 98110 or visit Ann’s blog at and leave a question / comment.

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