KiSwell® chitosan-based: the new generation of water-retaining granules for gardeners facing heatwaves

Daniel Platteau

The need: gardening through heatwaves that are now the norm

Summers are changing. Heatwaves follow one another, water restrictions last longer, and watering pots, young shrubs or a vegetable patch becomes a daily juggling act — with a dose of environmental guilt thrown in. The amateur gardener, already dealing with soil that dries out fast and plants that suffer, is looking for concrete solutions.

This is where water-retaining granules, or superabsorbent polymers (SAPs), come in. Their promise is simple: store water in the soil near the roots to smooth out drought peaks, then release it gradually to the plant. Until now, this category has been dominated by synthetic, often petrochemical, products — which European regulation is now preparing to phase out. That opens the door for a new generation of products.

KiSwell®: chitosan, not petrochemistry

KiSwell® is a water-retaining granule developed by the French startup Biomanity. Its innovation lies mainly in its raw material: chitosan, a natural biopolymer derived from chitin, extracted from crustacean by-products (shrimp and crab shells). It is one of the most abundant natural biopolymers on the planet, widely studied in agronomy for its biocompatible and biodegradable properties.

The product's claimed benefits, according to its designer:

• massive absorption and gradual release of water at root level;
• a possible reduction in irrigation needs (up to 50% claimed in favourable cases);
• stimulation of soil biology and the root system;
• reduced use of chemical fertilisers;
• no microplastics or persistent residues — unlike conventional petrochemical SAPs.

So this isn't just another water-retaining product: it's an attempt to widen the category toward a profile that is far more acceptable, both agronomically and from a regulatory standpoint.

How it works, explained simply

A water-retaining granule is a granular hydrogel. The process works as follows:

1. Mixing into the soil: the granules are worked into the planting substrate (pots, open ground, vegetable beds);
2. Watering: on contact with water, the granules swell and absorb a considerable amount of it — up to several hundred times their own weight for the best-performing products;
3. Localised storage: the water is held right next to the roots, without draining away or evaporating;
4. Release on demand: the plant draws on this reserve as needed, especially during periods of water stress;
5. Recharge cycle: the granules recharge with every watering or rainfall.

The chitosan used in KiSwell® adds an extra dimension: some studies suggest it also has properties that naturally elicit plant defences, though this still needs to be confirmed under the product's real-world conditions.

The water-retaining granule market: who else is out there?

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The SAP industry has been around for decades, and several products have established themselves as references:

What they all have in common: reducing watering needs and better managing the plant's water stress. What differs is the raw material and the environmental impact once the product reaches end of life.

Is it worth it for the amateur gardener facing heatwaves?

Yes, under a few conditions:

Where it makes sense

• Planters and pots: containers dry out fast, a water-retaining granule stabilises moisture;
• Planting young trees, shrubs, perennials: helps them establish successfully through summer;
• Intensive container vegetable growing: tomatoes and courgettes in particular benefit;
• Gardeners who are often away: eases watering needs over weekends and holidays.

Where it's less relevant (worth saying plainly)

• In heavy soil that's already well structured, classic organic amendments and mulching remain the foundation;
• Over large areas of open ground (a lawn, a big vegetable plot), the cost can be prohibitive;
• It's a complement, never a substitute for good practices (mulching, soil amendments, variety choice, rainwater harvesting).

An essential word of caution

KiSwell® is presented as a "bio-based alternative" to traditional SAPs — a genuine plus. But:

1. the exact composition and real-world biodegradability across different soil conditions still need to be confirmed by the manufacturer;
2. check compliance with local regulations on soil amendments;
3. as with any water-retaining product, run a small-scale trial before extending its use;
4. chitosan, derived from crustaceans, warrants a note for anyone with a shellfish allergy (unlikely to be triggered by handling soil, but worth mentioning).

Conclusion: a revolution announced, tempered enthusiasm

KiSwell® isn't empty media buzz: it's a serious player tackling a real limitation of the water-retention industry — the dependence on petrochemical polymers. Chitosan is a promising raw material, and if the product delivers on its promises in the field (something still to be demonstrated through independent publications under real-world conditions), it could become the go-to solution for responsible gardening through heatwaves.

With summers growing longer and harsher, the water-retaining granule is no longer a gimmick. But choose it carefully: check the composition, favour products with publicly available technical data, and don't forget that the foundation remains mulching + soil amendment + smart water management. KiSwell® — if its performance holds up — is an excellent candidate in that approach.

Sources

• Official Biomanity communications / press releases
• KiSwell® technical data sheet (to be added)
• Stockosorb® / Evonik technical data (to be added)
• TerraCottem® website and documentation (to be added)
• Scientific publications on bio-based SAPs and chitosan in agronomy (to be added)
• European regulation on fertilisers and superabsorbents (to be added)