Don’t Throw Out Potato Peels: How To Turn Them Into Powerful Natural Fertiliser
Every year, countless Zimbabwean households and smallholder farmers peel potatoes only to discard the skins as waste. Yet these humble potato peels hide a treasure trove of nutrients that can transform soil health and significantly boost garden productivity when reused correctly. As Zimbabwe pursues its National Development Strategy 1 (NDS1) to promote sustainable agriculture, such simple, cost-free fertiliser alternatives offer great promise for resourceful farmers across the country, especially women and youth cultivating home gardens.
Potato peels are a golden source of starch and minerals. On a dry-matter basis, they contain roughly 75% carbohydrates, including about 16.5-20 grams of starch per 100 grams of fresh potato. This starch fuels soil microorganisms that improve soil structure and fertility by breaking down organic matter. Berry crops like currants and gooseberries, which also grow well in Zimbabwe’s climatic zones, benefit immensely from this natural stimulation.
In addition to starch, potato skins are rich in potassium — often referred to as a “quality nutrient” in horticulture because it supports photosynthesis and sugar translocation within plants, enhancing the size, flavour, and quality of fruits. One hundred grams of raw potato skin can contain over 400 mg of potassium along with magnesium, phosphorus, calcium, and trace elements essential for balanced plant nutrition.
When potato peels decompose, the resulting organic matter loosens compacted soils, making them more crumbly and friable, thus improving aeration and root penetration. The peels’ relatively low carbon-to-nitrogen (C:N) ratio of 15-20:1 means they decompose quickly, but for optimal effects, they should be balanced by “brown” materials like dried leaves or shredded paper to maintain soil harmony and avoid nutrient imbalances.
Farmers in Zimbabwe can utilise potato peels effectively in three main ways:
Direct burying: Fresh or thawed peels can be dug into the soil beneath shrubs or crops during the growing season. However, frequent digging risks damaging delicate shallow roots.
Under mulch: Spreading peels on the soil’s surface and covering with a thick layer of mulch offers a gentler nutrient release, though the benefits take longer to manifest.
Starch infusion: This involves drying potato peels and steeping them in water to produce a liquid fertiliser that can be watered directly onto plants. This method is popular among gardeners for its ease of application and rapid impact.
To prepare potato peels for starch infusion, follow these simple steps:
Collect potato skins after peeling, avoiding any greened or spoiled pieces.
Dry the peels in a thin layer on a tray placed in a warm, well-ventilated area to prevent mould and ensure they become brittle.
Grind the dried peels into small crumbs or powder using household tools such as a blender, coffee grinder, or rolling pin.
Store the dried peel powder in a dry, cool, and airy container such as a paper bag or jar until needed.
To make the starch infusion:
Measure out approximately 1 kilogram (2.2 lbs) of dried, crushed potato peels.
Pour about 10 litres (2.6 gallons) of water, preferably warm, over the peels.
Allow the mixture to steep for about three days, stirring occasionally to release nutrients into the water.
Use roughly 3 litres (0.8 gallons) of this infusion per shrub. Apply during flowering, fruit set, and before the ripening period for best results. An additional watering in late summer (August) helps strengthen shoots ahead of colder conditions.
Farmers should be cautious never to use peels from spoiled or disease-affected potatoes, as this may spread pathogens back into the soil, jeopardising crops.
For gardeners without access to potato peels or who prefer a shortcut, plain potato starch can be used:
Mix 250 grams (8.8 oz) of potato starch with water, ensuring no lumps form.
Cook into a thick jelly using about 3 litres (0.8 gallons) of water.
Once cooled, dilute the jelly further with 10 litres (2.6 gallons) of clean water.
Water plants as with potato peel infusion.
While simpler, this starch jelly lacks some of the natural potassium and trace minerals present in whole peel infusions.
In Zimbabwe’s context, adopting potato peel fertilisation supports sustainable goals by recycling household waste into valuable nutrients, reducing dependency on costly synthetic fertilisers that many smallholder farmers cannot afford. Women, who traditionally manage family gardens, and young farmers can particularly benefit by increasing yields and soil health through this low-cost method.
Integrating such organic fertilisers aligns with NDS1’s vision of climate-smart agriculture and rural development, enhancing food security and empowering communities to steward natural resources effectively. Zimbabwe’s agricultural extension officers can promote workshops demonstrating this method to spread knowledge, especially in rural districts where organic inputs are scarce.
By recognising the value in what was previously discarded, Zimbabwean farmers can forge a future where healthy soils and bountiful harvests support livelihoods, nutrition, and environmental stewardship alike.
FFA Explainer Box
“Carbon-to-nitrogen ratio (C:N) is a measure of the amount of carbon relative to nitrogen in organic materials. Materials with a low C:N ratio, typically under 25:1, decompose faster, releasing nutrients to plants more quickly.”
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