To garden sustainably and protect the environment, turn to natural alternatives to chemical pesticides. Certain plants serve as green manures—planted directly in holes, used as ground cover, or fermented into sprays and watering solutions.
Liquid manures, or fermented plant extracts, act as stimulants, repellents, and fortifiers to strengthen and protect plants. The plants used—prepared as manures, decoctions, or infusions (some requiring boiling)—are packed with trace elements, organic matter, and minerals. During maceration and fermentation, these beneficial substances release into the water.
Experienced gardeners favor nettle, comfrey, horsetail, and ferns for manures, but tomato leaves, rhubarb, mugwort, compost, and even slug traps work too. Weeds like horsetail and nettle gain a valuable role in organic practices.
The standard recipe: Macerate 1 kg of coarsely chopped fresh plants in 10 liters of water for 1-2 weeks, depending on temperature. Variations exist by plant. Dilute to 10-20% and apply as a foliar spray or base watering.
Scientific studies on manures and decoctions are limited, but decades of gardener experience—backed by rare analyses from organizations like FREDON and INRA—confirm their benefits.
Nettle manure, nitrogen-rich, balances soil iron and nitrogen levels. Young batches (under 3 days) repel insects; mature ones fertilize and boost growth. Horsetail, high in silica, fortifies plants against fungal diseases.
For best results:
— Use rainwater, not chlorinated tap water;
— Mix in wood or plastic containers, never metal;
— Filter finely through cloth for residue-free storage;
— Store in opaque bottles (like recycled milk jugs) filled to the brim in a cool spot.
Fermentation creates a strong odor—part of the natural process.
Forage responsibly: Avoid roadsides or chemically treated fields.
Tomato manure recycles pruned leaves effectively, preventing leek moth, flea beetles, cabbageworms, and treating aphids.
Embracing plant manures commits you to natural garden management—ditching synthetic pesticides with their harmful side effects—and harnessing nature to nurture your garden.
Co-editors: Myrtille Vanardois / Daniel Lys
