Avoid ‘smoking the greenhouse’ to boost your roses’ vase life

Smoking the greenhouse, which involves sweeping up the rubbish in a greenhouse and burning it with the vents closed, is likely causing measurable loss of vase life among roses shipped to the Netherlands from Kenya and Ethiopia, FlowerWatch data have shown. Avoiding this practice may extend these roses’ vase life by as many as six days.

Routine vase life testing at FlowerWatch exposes cause of major vase life loss for roses

The damaging practice of smoking the greenhouse came to light as a result of routine vase life testing at FlowerWatch, explains CEO Jeroen van der Hulst . ‘In our vase life tests of Kenyan roses – which run in the thousands per year and cover flowers for major European retailers – we were observing more and more roses suffering from short vase life. Growing quantities of roses from Kenya and Ethiopia were failing to meet the seven-day vase life guarantee. We often filter out flowers that are wilting prematurely due to poor bucket washing or botrytis. These roses, however, weren’t wilting; they were opening poorly, with the petals drying out – a sign of emergency flowering, often caused by excessive levels of ethylene. Our Data-Driven Insights approach kicked in, and we used a mobile gas chromatograph to collect more data, testing for ethylene throughout the supply chain. Some ethylene was exposed – but not nearly enough to explain the problem. Neither our audits nor any other data points brought to light any major sources of ethylene in the chain.’

An unexpected source of ethylene

The answer presented itself at one of FlowerWatch’s recent Knowledge Days, when a Kenyan participant asked the FlowerWatch Team, ‘What do you think of the habit of smoking the greenhouse?’ ‘It turned out,’ says Jeroen, ‘that, unknown to us, as many as 80% of the farms represented at the event apply this practice several times a week, believing it helps to control thrips, a major pest for greenhouse crops. What these farmers were not fully aware of is that smoking the greenhouse also generates substantial amounts of ethylene – a gas to which some 30% of rose varieties are highly sensitive.'

On the basis of its data, FlowerWatch states that reducing the practice of smoking the greenhouse – and eliminating thrips in other ways – may add two, or even as many as four to six days, to the vase life of Kenyan and Ethiopian roses. ‘Just imagine the reduction of rejects and waste this would yield at European flower shops – and the number of consumers no longer ending up disappointed with their roses,’ says Jeroen. ‘We understand that thrips can be a threat, but too much ethylene from fire smoke may lead purchasers to avoid roses in favor of easier products, like Dutch tulips – putting rose farms under pressure.’

Greenhouse smoking history

Smoking the greenhouse has a long history, notably in pineapple growing. Before reefer logistics – with refrigerated trucks – made pineapples affordable as a fresh fruit in supermarkets around the world, the market in Europe was supplied from the Portuguese Azores islands, explains Jeroen. ‘Growers there have been producing pineapples for more than 150 years. They expose the plants to high levels of ethylene to induce flowering and fruit setting. One effective way of doing this is to rake all the rubbish and plant debris inside the greenhouse together in a heap, set it on fire, and leave it to smolder during the night. The smoke helps to produce more than enough ethylene for the plants to switch into generative mode.’

Jeroen also notes that at high-altitude farms in Ecuador and Colombia, smoking the greenhouse is practiced as a means of protecting flowers against night frost. ‘While these benefits may be real, our data show that avoiding the practice on rose farms offers growers an important opportunity to boost vase life – and the reputation of their roses.’

Combining human expertise with relevant supply chain data is the best way to take the flower sector to the next level

Taking the sector higher

In addition to presenting an opportunity for rose farmers to up their game, the ethylene investigation has highlighted the importance of combining data with human insights and interaction, comments Jeroen. ‘While our Data-Driven Insights programme is key for monitoring and optimising flower supply chains, interaction with the industry – for example through audits, farm visits, and our own regular Knowledge Days – is an integral part of taking our sector to the next level.’? ???

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