3 Steps for Making Comfrey Slurry
Garden Science

3 Steps for Making Comfrey Slurry

3 Steps for Making Comfrey Slurry


– Focus on the fertilizing properties of comfrey manure

– Step 1: Prepare the comfrey liquid manure

– Step 2: Filter and preserve

– Step 3: Dilute the comfrey liquid manure

– Use comfrey manure

Comfrey manure is an excellent fertilizer, with extraordinary fertilizing properties as crucial as those of manure. It is also used as a repellent against insects (e.g., aphids) and as a compost activator.

Making your comfrey manure is within everyone’s reach. This post explains the science of creating an organic comfrey slurry.

1. The fertilizing properties of comfrey slurry

Easy to grow in the garden, comfrey is a plant rich in potassium, calcium, and nitrogen (although its nitrogen content is lower than that of nettle). It is also rich in magnesium, copper, zinc, boron, and manganese.

Comfrey can be used as is, as green manure, or to make a slurry very useful in the organic garden. Comfrey manure stimulates plant growth, flowering, and fruiting. It is as beneficial for flowering plants (especially roses, as its magnesium content, protects them from diseases) as it is for fruits and vegetables (strawberry plants, red fruit bushes, tomatoes, peppers, artichokes, etc.).

2. Prepare comfrey manure

The preparation of comfrey manure takes about 15 days:

– Collect 1 kilo of fresh comfrey leaves.

– Chop them coarsely.

– Put them in a non-metallic container (wood, plastic) to avoid oxidation.

– Add 10 liters of water (as with all liquid manures, use preferably rainwater, less calcareous).

– Cover the container with a piece of cloth.

– Stir the mixture daily with a stick to promote fermentation.

– Let the mixture macerate for about 15 days:

o The exact fermentation time depends on the ambient temperature.

o In any case, the slurry is ready when the liquid is black, the leaves form a kind of mashed potato at the bottom of the container, and when there are no more bubbles on the surface, indicating that the fermentation phase is over.

3. Strain and store

– Put on gloves and filter this maceration finely (e.g., on a fine cloth) to remove all residues and obtain a clear liquid. Save the residue.

– Store the slurry in non-transparent bottles or cans (milk bottles work well).

– Close tightly.

– Store away from heat and light: with these precautions, the liquid manure will keep for a few weeks.

Good to know: comfrey manure does not smell as bad as nettle manure!

4. Dilute comfrey manure

Depending on its use, comfrey manure can be diluted more or less.

– 10% dilution: dilute your liquid manure at a rate of 10% in 90% water (for example, 1 liter of liquid manure for 9 liters of water).

– 5% dilution: dilute your slurry at a rate of 5% to 95% water (e.g., 0.5 liters of slurry to 9.5 liters of water).

Using comfrey manure

3 Steps for Making Comfrey Slurry

Comfrey manure can be used as an organic fertilizer, insect repellent, or compost activator.

Use comfrey puree as an organic fertilizer

To use comfrey manure as a fertilizer, there are two methods:

– Water at the base of your plants (with a watering can), using a 10% dilution.

– Or spray directly on the plants (with a sprayer):

o Pour 5% diluted comfrey slurry into your sprayer.

o Spray directly on the plants concerned.

Use comfrey puree as an insect repellent

– Pour 5% of comfrey slurry into your sprayer.

– Spray the plants concerned (for example, your roses).

– Repeat the operation if necessary.

Use the comfrey slurry as a compost activator

Add the leftovers from the filtration of your compost (leaf mashed potato) to your compost to improve its quality and speed up its decomposition.

Materials needed to make and use comfrey manure

Gardening gloves



Opaque plastic bottle

Watering can with apple

Pressure sprayer


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