Since 1992, family-owned Castleton Farm in Aberdeenshire has grown into one of Scotland’s leading soft-fruit producers, supplying major UK supermarkets, including M&S.

With current coir prices increasing dramatically as a result of the rising cost of fuel, transport and importation, Castleton Farm faced a challenge in managing recurring coir substrate expenditure.

Castleton, like many growers, had large volumes of spent coir accumulating on-site; representing tied up value. Doing nothing meant continuing to purchase high-cost imported virgin substrate blends, including buffered coir, while the valuable spent material went unused. Reusing the spent substrate in the absence of steam treatment is simply not viable; it would compromise crop performance, cause worse yields and carry high risk of disease carryover.

FlowSteama has enabled Castleton to safely and economically reuse the spent substrate for growing additional strawberries, raspberries, blueberries and cherries; enabling the immediate recovery and recycling of a super-useful, high-value material, improving yields and extending growing seasons.

Based on a typical, hypothetical situation, the chart below details the ongoing annual single-use coir input cost reductions enabled by the FlowSteama. Calculations are based on current market estimates, as of November 2026. Speak to our team to discuss your potential annual cost savings: enquiries@stronga.com

Composted coir (coconut husk fibre) and perlite blend, post heat treatment in the FlowSteama.

The FlowSteama Rova model supplied to Castleton Farms is capable of processing 12-16m³ of used coir blends per hour with a 20–30-minute time-at-temperature treatment period at 85’C, enough to remove all pathogens, harmful bacteria, diseases including (Botrytis cinerea), Powdery mildew (Podosphaera aphanis), and Anthracnose (Colletotrichum) and weed seeds.

In financial terms, FlowSteama immediately recovered the whole capital investment of the equipment within the first growing season including operating costs. Removing recurring coir input costs while offering long-term continued savings and sustainability and lowering CO₂, created a more cost-effective circular growing operation.

The FlowSteama Rova and SteamBoila (background) onsite at Castleton Farm in Scotland. Steam sanitised coir mix, discharged from the Rova in the client’s shed.

Stronga’s steam sanitisation equipment goes beyond simply reducing substrate costs. Independent trials have demonstrated that steam heat treating used coir at approximately 75’C+ can deliver more fruit per square metre than spent coir, improving growing productivity and the return from every crop.

In our own experience, FlowSteama customers have reported results confirming as much as a doubling of fruit yield after substrate blend heat treatment, demonstrating that steam sanitisation can revitalise the growth potential of coir, delivering outcomes exceeding virgin coir-based substrate.

Did you know? Repurposed, enhanced coir can also be used on other areas of the farm. It is known to improve soil structure, increase organic matter and contribute to sustainable agricultural output.

Castleton Farm have made regenerative farming and sustainability a priority.

Reusing untreated spent coir was not an option due to the risk of disease carryover (Botrytis cinerea), crop loss and impacts on fruit quality and compliance. Market-leading Stronga steam treatment equipment provides a clean approach to steam pasteurisation, enabling the safe reuse of the coir substrate while enhancing crop yield.

Benefits of Steam-Treating Coir with FlowSteama

Castleton Farm is a family-run Scottish fruit farm, farm shop, and food producer located in Aberdeenshire, owned by Ross and Anna Mitchell.

Castleton Farms recovered unseen value locked in its used coir blend compost heaps; a result from years of production, while improving performance and quality.

FlowSteama offers a compelling economically viable opportunity for closing the loop on horticultural waste: less reliance on purchasing new coir fibre and chips, better utilisation of existing idle assets, lowered coir input operating costs by 80% and extended fruiting season, enabling growers to supply high-value soft fruit markets earlier and for longer. Overall, FlowSteama allows you to prioritise your commercial returns.

Castleton Farm’s strawberry propagation polytunnels.

Castleton Farm is far more than a strawberry grower. Across roughly 1,400 acres, this impressive operation produces a diverse range of premium soft fruit, including strawberries, blueberries, raspberries and cherries. With hundreds of acres dedicated to soft fruit production, Castleton combines large-scale farming with sophisticated growing systems designed to produce high-quality fruit across an extended season.

Castleton Farm’s successful steam sanitisation integration demonstrates how innovation can transform what was previously a waste stream into a productive, high-value resource.

The heat-treatment process is simple, reliable and extremely well proven across many operations. The SteamBoila generates super-heated, low-pressure steam up to 200°C, providing the benefits of highly penetrative steam while avoiding many of the maintenance requirements associated with high-pressure systems.

The insulated FlowSteama vessel retains heat throughout the process while the agitation system continuously tumbles the used coir, exposing material evenly to the 200’C steam. This achieves a consistent, guaranteed temperature heat treatment profile throughout the substrate. The HMI touchscreen provides a measurable, repeatable and auditable treatment process, important when crop quality, food safety and supermarket compliance are critical.

The Castleton operation is demonstrated in the video below.

FlowSteama equipment offers a genuinely low carbon solution for soft fruit growers which is highly likely to attract regenerative farm grant aid support, which can turbocharge the return on investment. Scotland’s Fruit and Vegetables Aid Scheme is one example where growers can turbocharge return on investment.

By enabling coir reuse, reducing waste and CO² import emissions and improving resource efficiency, FlowSteama supports grower’s wider investment objectives. Eligibility and funding would depend on applicable criteria. Please contact Stronga for more information.

Talk to Stronga today and discover how FlowSteama can turn your used coir into a valuable, reusable growing resource, reduce substrate costs and unlock greater productivity from every growing cycle: enquiries@stronga.com