Bag of ZeroMix Guano Diffusion unfertilised potting compost, front face with the window showing the grow medium

50 L bag of ZeroMix compost standing on a wooden floor, in front of a dark wall

Unfertilised compost for you to feed yourself

8,90 €

Volume	Price	Price per L	vs 10 L
10 L	8,90 €	0,89 €	—
50 L	23,90 €	0,48 €	−46 %

ZeroMix is an organic potting compost that contains no fertiliser: blonde peat, coco fibre and chips, clay. You therefore decide for yourself what your plants receive, whether in pots, in the vegetable garden or in the greenhouse, with a water retention of 700 ml per litre and a pH of 6.

Ref. 99915·Growing medium

Volume : 10 l

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The summary

Ingredients: a compost made of blond peat, coir fibre and chips, and clay, with no fertiliser, plus added calcium and magnesium.
Why no fertiliser: the plants' nutrition depends entirely on what you supply, from planting onwards.
Its values: pH of 6, water retention of 700 ml/L, 92% organic matter on a dry basis.
With a pond: for the pots and tubs around the system, never in the grow beds.
Bags: 10 L for a few pots, 50 L for a balcony or a greenhouse.
Organic farming: a 100% organic compost, to be fed with a fertiliser approved for use in organic farming.

A neutral organic substrate, to be fed according to your own fertiliser programme

Guano Diffusion's ZeroMix is a fertiliser-free compost of blonde peat, coco fibre and clay, with a pH of 6. You feed it from planting onwards, for example with dried blood guano, after sowing in SeedMix. Sold in 10 or 50 L bags, it fills pots and trays, never an aquaponic bed.

Most commercial potting mixes are pre-fertilised: they sustain the plant for several weeks on a reserve of fertiliser whose exact dose and release rate you do not know. ZeroMix from Guano Diffusion takes the opposite approach. This potting mix contains no fertiliser, so everything the plant absorbs comes from what you supply. It is the medium to choose when you follow a precise feeding programme, organic or mineral, and want to avoid an unknown reserve being added on top.

🧱 Four raw materials

The blond sphagnum peat forms the base of the mix and gives it its lightness. The coco fibre retains water, while the coarser coco chips create spaces for air to circulate and prevent compaction over repeated waterings. The clay increases the grow medium's capacity to hold the nutrients you add, which limits their loss in the drainage water. Finally, a supplement of calcium and magnesium corrects the natural acidity of the peat without adding any nitrogen, phosphorus or potassium. Overall, the mix contains 92% organic matter on the dry product and retains about 700 ml of water per litre of compost, or 35 litres for a 50 L bag. With a pH of 6, most elements remain available to the roots, and the conductivity of 10 mS/m, measured in a 1:5 dilution, confirms a grow medium almost empty of salts.

💧 Feeding from planting

Because the grow medium starts from zero, feeding begins with the very first watering, rather than two or three weeks later as with an enriched potting compost. A fertiliser for soil is suitable, as is one formulated for coco fibre, given the proportion of coco in the mix. For a pot-grown vegetable garden run organically, a liquid organic growth fertiliser is added to the watering water at each pass; for closer monitoring, measure the pH of the solution before applying it. For a long crop, the dried blood guano from the same brand, mixed at 10 g per litre at planting, forms a base reserve whose content you know exactly, and the Startrex soil conditioner adds to it, at 25 g per 5 litres, the microbial life that a new compost lacks. You can thus adjust the dose at each stage, from growth to fruiting, with no hidden reserve to throw off your calculations.

Testing your fertiliser on a neutral compost

If you are looking for the right dose for a pot culture, ZeroMix gives you a clean basis for comparison: two pots, two doses, and the difference in growth owes nothing to the potting compost. To read what the plant is actually receiving, a drop-based pH test on the watering water completes the approach.

Without feeding, the plant turns yellow within a few weeks

Planting in this compost without a feeding programme leads to leaves that turn pale and then yellow, starting with the oldest, because of a lack of nitrogen. The grow medium is designed to be fed at almost every watering.

The 10 L bag fills a few houseplant pots or a small herb planter, while the 50 L bag covers a whole balcony or several large vegetable containers. The mix keeps well in its resealed bag, protected from frost and from drying out, so you can keep a reserve for this season's repotting. The article on choosing a grow medium compares this type of potting compost with the inert supports used in soilless growing, clay pebbles and pure coco fibre, which work on the same logic of nutrition supplied entirely by the grower. Seedlings, for their part, germinate in the SeedMix seed compost, which is finer and lightly fertilised, before moving into ZeroMix at the first repotting.

🪴 For which crops

Container vegetable garden

Tomatoes, peppers and herbs grown in containers receive exactly the formula chosen for each stage.

Houseplants

The light mix suits potting on, with a diluted fertiliser applied when watering.

Shrubs and borders

When planting out, it is worked into the soil in place to lighten it and hold water.

Lawn

When overseeding, it covers the seeds with a fine layer that stays moist.

🐟 Around an aquaponic system

Potting compost does not belong in an aquaponic grow bed. Peat and fine fibre break down in the circulating water, cloud the fish tank and clog the inert grow medium, clay pebbles or gravel, that the biofilter bacteria colonise. Seedlings intended for the system are therefore raised in an inert medium: the FAO recommends rockwool or coco coir, followed by transfer into the beds at least two weeks after the first true leaves appear. The rockwool blocks thus go into the baskets in the tank with their own clean root ball.

ZeroMix, on the other hand, finds its place with the crops you keep in pots beside the system: a tomato plant in a large tub, herbs on the greenhouse shelf, strawberries in a planter. As it contains no fertiliser, you apply your own feeding programme, independent of the fish water. Note that its pH of 6 is more acidic than that of an aquaponic system, which is run at around 6.8 to 7.0 to look after the fish, the bacteria and the plants alike: the two environments are managed separately.

Within the system itself, shortages are corrected with products made for fish water. Iron comes first: a DTPA chelated iron is applied at about 2 mg per litre every 3 weeks. Potassium and calcium are topped up by alternating small doses of calcium hydroxide and potash, which bring the pH back towards 7. The article on deficiencies in aquaponics helps you identify the missing element from the leaves, and the one on fertilisers in aquaponics distinguishes what can go into the fish water from what is reserved for pots.

Technical specifications

The compost

Composition: Blonde peat, coir, clayBlonde sphagnum peat, coconut fibre and chips, clay, calcium and magnesium supplement
Fertiliser: NoneFertilisation begins at planting
pH: 6Measured at a 1:5 dilution
Conductivity: 10 mS/mMeasured at a 1:5 dilution, almost free of salts
Origin: Made in France
Water retention: 700 ml/LAround 35 litres retained by a 50 L bag
Organic matter: 92% of the dry product
Dry matter: 35% of the raw product

Use and sizes

Crops: Pots, vegetable garden, shrubs, lawnOutside aquaponic grow beds
Volumes: 10 or 50 L

2 further specifications are available in the detailed view.

In the box

1 bag of ZeroMix compost, 10 or 50 L, depending on the size chosen

Composition, pH, conductivity, retention, dry and organic matter: manufacturer's datasheet (guano-diffusion.com). Aquaponic benchmarks: FAO, NMSU.

Manufacturer and product safety

Manufacturer: Guano Diffusion
Website: www.guano-diffusion.com

Information provided under Regulation (EU) 2023/988 on general product safety.

Estimate your
delivery time

The bag is sent from a distributor's warehouse in France, in a 5 kg parcel for 10 L and a 16 kg parcel for 50 L. The exact shipping cost is shown in your basket.

Frequently asked questions

6 questions

6 key questions

When should I start fertilising?

Which fertiliser should you use with this potting soil?

What is the difference from a standard potting compost?

Point	ZeroMix	Pre-fertilised compost
Fertiliser at the start	none	several weeks
First feed	at planting	once the reserve is used up
Control over the dose	total	partial

Which volume should you choose?

Can it be used to raise seedlings destined for aquaponics?

Can you reuse potting compost from one season to the next?

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Unfertilised compost for you to feed yourself

The summary