This report is from Farmers Weekly, dated 17 July 2026
In an interview with Farmers Weekly, Natie Ferreria (pictured here), owner of Dagga Farmacy Nursery and director at Cheeba Cannabis Consultancy, said that as South Africa’s cannabis sector continues to expand, post-harvest handling is emerging as one of the most critical and often overlooked stages in production, particularly for small-scale farmers.
Ferreira, says that while many producers are improving cultivation practices, significant losses continue to occur after harvest.
“Most growers can, after three or four seasons, get the growing side of things under control. There are strict programmes to follow for those who do not get it right intuitively,” he says. “But the moment they harvest, that is where the problems normally start.”
He explains that drying and storage require a level of environmental control that many smallholder farmers cannot yet afford.
“It is very difficult for a small grower to afford a full climate-control system. So drying and storage become an art, and many get it wrong,” says Ferreira.
He adds that this challenge is particularly visible in rural production systems where crops that initially appear to be of high quality often deteriorate rapidly after harvest due to poor handling.
Humidity, temperature and airflow determine quality outcomes
Ferreira identifies humidity control as the single most important factor in post-harvest quality preservation.
“In a summer rainfall area, humidity fluctuates constantly. You do not want it to exceed 60%. If it does, the flower oxidises and turns brown even without fungal infection,” he says.
Humidity above 60% can cause cannabis flowers to oxidise and turn brown even without fungal infection.
He warns that overly dry conditions are equally problematic.
“If the flower dries too fast, the outside becomes dry while the inside remains moist, which creates the perfect environment for fungal growth,” he says.
Temperature further compounds the risk.
“Above 20°C, degradation processes accelerate. Combined with poor humidity control, this can lead to fungal outbreaks such as botrytis and result in total batch rejection,” Ferreira explains.
Air movement also plays a key role.
“You need consistent air exchange to remove stale air, but airflow must not blow directly onto the flower,” he says.
He adds that drying rooms should remain dark, as light exposure accelerates oxidation and reduces product quality.
Storage conditions now define quality preservation
With curing largely absent in commercial systems, Ferreira says storage has become the primary stage for preserving quality. Optimal conditions require tightly controlled environments.
“You want humidity between 55% and 60% and temperatures ideally around 12°C to 16°C,” he says.
He cautions that extreme cold must be carefully managed.
“If you go too cold and then move the product, condensation can form, which is not desirable,” he says.
Strict hygiene protocols are also essential.
“The room must be kept clean, with full hygiene protocols and protective clothing. It must be treated like any pharmaceutical environment,” Ferreira explains.
He adds that airflow stability is critical, as frequent human movement can disrupt environmental consistency.
Packaging and materials directly affect shelf life
Ferreira says packaging plays a major role in maintaining long-term product integrity.
“We use light-blocking Mylar materials that prevent both air and light exposure,” he says.
However, he notes that glass remains the most inert storage option. “If you want the best preservation, glass is ideal because it does not react with the product,” says Ferreira.
Due to cost and scalability, most commercial operations use food-grade plastic containers instead. Ferreira warns that high-terpene strains can interact with certain plastics over time.
“Some terpenes act as solvents and can degrade plastic materials,” he says. For this reason, he recommends glass or certified food-grade plastic, particularly for smaller-scale producers.
Contamination risks require strict hygiene and airflow control
Ferreira warns that contamination risks begin at the point of human handling and environmental exposure.
“Hair, dust and even clothing can introduce contamination during trimming and processing,” he says.
It is therefore important to use personal protection equipment such as gloves, hair nets and beard nets.
Beyond physical contamination, airborne spores present a significant risk.
“We are constantly surrounded by fungal spores. “They only become a problem when conditions allow them to germinate,” he explains.
To mitigate this, facilities must use HEPA (high-efficiency particulate air) filtration and maintain negative air pressure.
“You need filtered air coming in and negative pressure, so external air cannot enter uncontrolled,” says Ferreira.
He adds that reusable containers must be properly sterilised or replaced between batches to avoid cross-contamination.
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