Block of compressed coco coir removed from its packaging, dense brown fibre block on a white background

Rehydrated coco coir held in both hands, airy texture blending peat, fibres and chips

UGro XL Rhiza 70 L compacted coco fibre block, full packaging seen from a three-quarter angle on a white background

UGro Slab Rhiza 15 L grow bag, one-metre-long coco coir block, on a white background

UGro implementation diagram for the 15 L bag: cutting the windows, hydrating, making drainage slits, placing the plugs

Compressed coco fibre brick seen at three-quarter angle on a white background

UGro Slab Rhiza 15 L coco coir block in its one-metre white packaging, placed diagonally on a white background

Hydrated coco coir expanded view – swollen coco substrate for aquaponic grow bed

Compressed coco fibre, 15 or 70 L

¥1,500

Volume	Prix	Prix au L	vs 15 L
15 L	¥1,500	¥100	—
70 L	¥3,500	¥50	−50 %

A compressed coco fibre block weighs 1.6 kg and sits neatly on a shelf. Soaked in water, it expands to give fifteen litres of ready-to-plant grow medium.

The fibre is double-washed in fresh water and buffered at the factory: it comes out of the bag at pH 5.5 to 6.5. The 15 L grow bag can be planted straight away; the 70 L block fills your own pots and baskets.

Volume : 15 l

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Payment in instalments, free of charge

The summary

What you receive: a washed and buffered UGro Rhiza coco block, in a 15 L bag or a 70 L block.
How long it takes: 2 to 3 minutes to expand for the 70 L block, a resting period for the 15 L bag.
Preparation: 6.5 L of clean water for the 15 L size, 18 L for the 70 L, and a container sized for the final volume.
Before use: a rinse with clean water, the runoff from which must not return to the fish tank.
Maintenance: none for the grow medium itself — only the watering or fertigation of your crops.
How to choose: the 15 L bag can be planted directly as it is; the 70 L block fills your own pots.

Washed and buffered coco coir for seedlings, pots and grow beds

A block of compressed coco weighs 1.6 kg and fits on a shelf. Left for a few minutes in a bucket of water, it yields 15 litres of grow medium ready for planting. That is the whole point of compressed coco: you store a dense block all year round and produce the growing volume on the day you need it, without cluttering a garden shed all winter.

The 15 L bag

It is a flexible growing bag of around one metre, UV-treated, which you simply set down and plant into as it is.

The 70 L block

This is a block to rehydrate in a container, ready to fill your own pots and baskets.

💧 Preparing a loaf

No tools are needed for preparation. The 70-litre block requires 18 litres of clean water and expands within two to three minutes in a large tub or wheelbarrow. The 15-litre bag is prepared differently: cut one of the four marked openings on the top, pour 6.5 litres of clean water through the opening, then allow capillary action to distribute the moisture before planting. Allow a good hour before the bag is uniformly moist along its entire length.

🌿 Coco coir in aquaponics

In aquaponics, coco is used as a planting medium in pots and baskets. It holds the root ball, keeps the roots cool, and provides a surface for bacteria to colonise. Keep it for this purpose rather than filling a flood-and-drain bed entirely, where its fine texture eventually compacts the grow medium and restricts flow. The guide on which grow medium to choose in aquaponics compares each option one by one.

Rinsing, dosing, placement

The commissioning rinse must not be skipped, as in aquaponics it prevents the first wash-off water from reaching the fish tank. Run the rehydrated grow medium under clean water and drain this water away elsewhere. Soaking the block serves no purpose either, since beyond the quantities indicated the coco loses volume and compacts instead of remaining aerated. Finally, keep it away from any permanently flooded area of the bed, where its fine texture causes it to migrate towards the strainer and the pump.

Rehydration equipment

Have a basin, rehydration water and a complete fertiliser ready, as coco coir provides no nutrition on its own and everything depends on what you add. If you are filling your own pots and baskets, the 70-litre block is what you need; the 15-litre bag is designed to be planted as it is, without opening.

♻️ After growing

Used coir does not necessarily have to be thrown away. After a healthy crop, it can be shaken to remove the roots, rinsed thoroughly and used a second time, with slightly reduced water retention and a somewhat finer structure. After a root disease outbreak, however, it goes to the compost rather than into the next pot, as a fibrous grow medium retains spores far more readily than a mineral one. Compost is, in fact, its natural end of life: coir fibre breaks down slowly while improving the structure of a heavy soil.

Technical specifications

The essentials

Volume once hydrated: 15 or 70 litresDepending on the capacity chosen.
Rehydration water: 6.5 or 18 litresDo not exceed this amount: beyond it, the coco compacts instead of staying open.
Grow medium pH: 5.5 to 6.5Range in which most vegetables absorb minerals most effectively.
EC conductivity: Below 0.6 mS/cmOn fresh grow medium, before any fertiliser application.
Water retention: 40 to 65% depending on size40 to 45% for the 15 L bag, 60 to 65% for the 70 L block.
Reuse: A second season in a potRemove the large roots and re-moisten the grow medium, provided the previous crop did not suffer from root disease.

To budget for separately

Water and container: 6.5 or 18 L of clean waterPlus a bowl, a wheelbarrow or a container large enough for the final volume.
Fertilisation: A complete fertiliserAll nutrition comes from what you add, from the very first watering.

In the box

1 growing bag of 15 hydrated litres, with 4 marked planting slots to cut open, drainage holes on the underside, and a UV-stabilised film (15 L variant)
1 compressed block of 70 hydrated litres, 32 x 32 x 14 cm, film-wrapped with a carry handle (70 L variant)

Hydrated volume, rehydration water, pH, conductivity, retention and weight: figures supplied by the manufacturer, recorded on 10/09/2026. Retention and structure vary between formats; full details are given under each line.

15 litres or 70 litres: which one is right for you

Both sizes contain the same washed and buffered coco, but they are prepared differently and serve different purposes.

The same coco, two ways to set it up The bag is planted as it is, with no need to transfer anything. The block is expanded in a tub and fills your own pots, in one go or in stages.

	Volume once hydrated (L)	Clean water required (L)	Weight of the parcel to carry (kg)	Packaging	Coco structure	Water retention	Enriched with endomycorrhizae	Prepared in several stages	Ready to plant with no repotting	Fills your own pots and baskets	Price	Best volume-to-price ratio
15 L growing bagYour choice	15 L	6,5 L	1,6 kg	Flexible bag with marked cut-out slots	Medium coco, long fibres and chips	40 to 45 %	Yes	No	Yes	No	¥1,500	No
Recommended 70 L compressed blockYour choice	70 L	18 L	5 kg	Block under film, 32 x 32 x 14 cm	Medium coco with a medium fibre content	60 to 65 %	Yes	Yes	No	Yes	¥3,500	Yes

15 L growing bag

Format and rehydration

Volume once hydrated (L)15 L

Clean water required (L)6,5 L

Weight of the parcel to carry (kg)1,6 kg

PackagingFlexible bag with marked cut-out slots

Grow medium behaviour

Coco structureMedium coco, long fibres and chips

Water retention40 to 45 %

Enriched with endomycorrhizaeYes

Prepared in several stagesNo

In use

Ready to plant with no repottingYes

Fills your own pots and basketsNo

Price¥1,500

Best volume-to-price ratioNo

70 L compressed blockRecommended

Format and rehydration

Volume once hydrated (L)70 L

Clean water required (L)18 L

Weight of the parcel to carry (kg)5 kg

PackagingBlock under film, 32 x 32 x 14 cm

Grow medium behaviour

Coco structureMedium coco with a medium fibre content

Water retention60 to 65 %

Enriched with endomycorrhizaeYes

Prepared in several stagesYes

In use

Ready to plant with no repottingNo

Fills your own pots and basketsYes

Price¥3,500

Best volume-to-price ratioYes

Technical values taken from the Slab Professional Rhiza and XL Rhiza data sheets.

Product videos

A UGro XL 70 L block expanding in real time

Rehydrating a coco fibre block, step by step

Growing in coco coir: the basics

Preparing and planting a UGro grow medium, demo on the Small format

Growing in coco bags explained

Documents & manuals

Catalogue UGro Coco, Tree of Life 2024

Full range of UGro coco grow media and the characteristics of each product. English and Spanish.

PDF · 4,4 Mo

Download

UGro 2022 range leaflet

Detailed compositions of the Slab 15 L and XL 70 L, weights and volumes. English and Spanish.

PDF · 2,9 Mo

Download

UGro product catalogue

Condensed datasheets for the full range, dimensions and pack sizes. English and Spanish.

PDF · 3,3 Mo

Download

Rhiza 1200 instructions, the mycorrhizal inoculant

Manufacturer's document on endomycorrhizae in the Rhiza range. In English.

PDF · 2,2 Mo

Download

Estimate your
delivery time

The 70-litre block weighs 5 kg; the 15-litre block approximately 1.5 kg. The exact delivery cost is calculated in your basket based on the total weight of your order.

Frequently asked questions

6 questions

6 key questions

Which capacity to choose between 15 and 70 litres?

Format	Water to add	Getting started	Suited to
15 L grow bag	6,5 L	Plant straight away: cut along the marked slots on the top.	A growing table, a gutter, or a workstation already in use.
70 L compressed block	18 L	Expand in a container, then distribute into your own pots and baskets, all at once or in stages.	Those who already have their own containers, space to work, and don't mind a little handling.

Per hydrated litre, the 70 L block works out considerably cheaper than the 15 L bag. The comparison between the two formats comes down to three questions.

Coco fibre or clay pebbles: which to choose for soilless growing?

These are two opposing functions, which are often complementary rather than competing.

Clay pebbles drain. Clay pebbles shed water very quickly and retain almost none: they are designed for flood-and-drain beds with short cycles, where the grow medium must empty completely at each cycle, and for base drainage.

Coco retains moisture. It holds water between waterings, with a capacity of 40 to 45 % for the 15 L bag and 60 to 65 % for the 70 L block. It is therefore well suited to pots, planters, seedlings and all plants that do not tolerate sudden changes in moisture levels.

Sphagnum and perlite serve different purposes. Sphagnum retains considerably more water and holds its structure for a long time, but it is expensive per litre and is used mainly for cuttings, orchids and carnivorous plants. Perlite is not a complete grow medium: it is added to coco to lighten it. Soil, on the other hand, introduces nutrients you cannot control, which is a disadvantage in soilless growing.

For a full overview, see our article on choosing a grow medium in aquaponics and the grow media collection.

How much water is needed to rehydrate a coco fibre brick?

6.5 Lfor the 15 L bag

18 Lfor the 70 L block

2 to 3 minfor the block to expand

Do not exceed these quantities. Fill the bag with clean water through one of the pre-cut openings on top, then leave it to stand while capillary action distributes the moisture evenly; the block expands in a large basin.

Adding more water does not produce more grow medium: the material becomes saturated, loses volume and compacts, which is detrimental to root development.

One side of the 15 L bag may appear wetter than the other at first: this is normal, as the coco's capillary action distributes the water on its own.

Should you rinse coco fibre before using it in aquaponics?

This coco coir can be planted straight after rehydration, with no further preparation. In aquaponics, do carry out a start-up rinse beforehand, as the first flush of water would otherwise flow directly into your fish tank.

Rehydrate the block with the specified amount of water: 6.5 L for the 15 L bag, 18 L for the 70 L block.
Break the material apart by hand or with a cultivator.
Rinse it under clean running water until the water runs clear.
Discard this first rinse water in the garden or down the drain — never into the fish tank.

This coco coir has already been double-washed and buffered at the factory, with a conductivity below 0.6 mS/cm. Even so, coir fibre retains a high cation exchange capacity: when it comes into contact with soft, mineral-poor water, it releases some of the potassium and sodium still bound to it.

Does coco fibre lower the pH of the water?

How do you store an unused coco coir block?

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Compressed coco fibre, 15 or 70 L

The summary