It's possible to make your own wormwood (Artemisia absinthium) fertiliser, a natural plant food for your garden. Made from fresh plants, this fertiliser acts as a repellent against mites, slugs, snails and insects. It's also effective against certain fungal diseases like rust and leek moth. This powerful aromatic plant grows easily in gardens or vegetable patches.
You can buy it ready-made or try making your own wormwood fertiliser at home. Rich in thujone, wormwood is a natural insect repellent, fungicide and pesticide, and when used in fertiliser, it becomes essential for natural gardening. Here's the recipe to make this potion, how to use it and its benefits.
Discover how to prepare wormwood fertiliser and use it properly, either diluted or neat!
Discovering Wormwood
This aromatic perennial is easy to grow in gardens. Artemisia absinthium is also known as grand wormwood, absinthe, absinthium, common wormwood or mugwort. It thrives in both sun and partial shade, adapts to all soil types and can quickly become invasive. It develops fine silvery leaves and small yellow flowers in summer. Its strong scent repels insects, hence its repellent and insecticidal properties.
Required Equipment
To make 10 litres of wormwood fertiliser, you'll need:
- A bucket or any non-metallic container
- Another container for filtering
- A cloth
- 1 kg of fresh wormwood
- 10 litres of non-chlorinated, non-calcareous water
- A stick
- One or two plastic containers
- A pair of gloves
- A pair of secateurs
- A funnel
Wormwood foliage. © Nicolas Weghaupt, Public Domain
Step-by-Step Fertiliser Preparation
To make fermented wormwood extract, follow these key steps:
1) The Recipe
For making fertiliser, it's best to use rainwater or non-calcareous water as limestone blocks the absorption of active compounds. The water shouldn't be chlorinated either – if it is, let it stand for 48 hours while stirring occasionally to reduce chlorine content. For containers, prefer plastic or wood. Metal may oxidise and compromise the preparation.
To make about 10 litres of wormwood fertiliser, you'll need to harvest 1 kg of fresh leaves and flowering tops for 10 litres of water.
2) Harvesting
Using secateurs, gather fresh leaves and flowers at the start of flowering. If you don't have fresh wormwood, you can use dried plants – about 30 grams of dried wormwood per litre of water. Weigh approximately 1 kg of leaves.
3) Preparing the Fertiliser
Place the leaves and flowers (unchopped) in the container and add water. Cover with an old cloth to allow fermentation gases to escape and let the mixture steep for 10 days. Keep the container in a shaded spot.
4) Stirring the Fertiliser
Using a stick, stir the mixture daily for at least 10 minutes.
5) Fermentation
Depending on temperature, fermentation may take 10-15 days. When you see no more bubbles or white foam on the surface, fermentation is complete and the fertiliser is ready. If left too long, the mixture will rot and you'll need to start again.
5) Filtering
Using a sieve or old cotton cloth, filter the mixture to remove plant residue. Any impurities could clog your spray nozzle!
6) Transferring the Fertiliser
Once filtered, use a funnel to transfer the fertiliser into opaque, labelled plastic bottles with airtight lids. For safety, store them on a high shelf in a cool, ventilated room. Avoid heat exposure.
Storing Wormwood Fertiliser
Use opaque plastic bottles with airtight lids to preserve the fertiliser's properties. Store in a dark, well-ventilated area away from heat. Wormwood fertiliser keeps for several months until you prepare a new batch.
How to Use Wormwood Fertiliser in the Garden
This fermented extract is highly effective in the garden against:
- Cabbage white butterflies, carrot flies, asparagus flies, onion flies, flea beetles, caterpillars, leek moths, aphids, ants and codling moths – use as an insect repellent and insecticide;
- Slugs and snails – use as a repellent;
- Diseases like currant rust – use as a fungicide.
Wear gloves when handling the fertiliser.
Use it neat or diluted in a sprayer depending on application:
- Dilute to 10% (1 litre fertiliser to 9 litres water) against codling moths or cabbage whites. Spray trees or vegetables before and during butterfly emergence and caterpillar hatching. Treat every 15 days from early June to late July during egg-laying periods;
- Use neat against flies (carrot, asparagus, onion), moths, rusts, aphids, currant rust and slugs. Repeat spraying after 10 days if needed until pests disappear. As with all plant extracts, use sparingly!
Apply sprays in the evening or morning during dry weather. Avoid sunny days to prevent plant scorching.
For more homemade fertilisers, read our guide on nettles and their benefits, and discover our tutorials: How to Make Nettle Fertiliser, How to Make Fern Fertiliser, How to Make Comfrey Fertiliser and How to Make Horsetail Fertiliser.
Discover other artemisias like Artemisia vulgaris and valuable growing tips in our article about planting, pruning and caring for artemisia.
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