The process of harvesting roses to prepare them for essential oil distillation is delicate and complex. Roses are usually planted around the end of January, a process which lasts up to 75 days. Planters dig grooves in the plantation soil, in which carefully cut rose seedlings are planted, covered in rich fertilizer and manually watered in times of rain scarcity. The roses are planted close to the earth and trimmed constantly in order to keep them from exceeding 1.5 meters in height. Keeping them low to the earth like this encourages the rose bushes to produce as many roses as possible each morning (Arab News, source, 2012).
The rose is usually harvested at the end of spring and beginning of summer, often towards the end of May into June. Rose petals contain most of the rose essential oil, although the stamens have been discovered to contain some oil as well, and these are sometimes distilled along with the petals. The rose petals contain rose essential oil in very small amounts, below 1% (Gernot Katzers, source, 2003). Thus, thousands of rose plants are needed to produce enough rose oil for a viable rose distillation business; about 60,000 roses are needed to produce just one ounce of oil, and ten thousand pounds of rose blossoms are required to produce one pound of oil. Mild and humid weather extends the flowering period, which increases both the quality and yield of the oil produced (Guenther, E. (1952) The Essential Oils. London: Macmillan).
Harvesting rose petals is a labor-intensive task. Petals are hand-picked by workers to ensure that they are not damaged, and the average amount of rose petals gathered per worker is three kilograms (6.6 lbs) per hour, although this number varies and many workers harvest rose petals at a much slower rate (International Herb Association, source, 2014). Considering the average, well-kept rose plantation yields approximately 4,000 kgs of flowers per hectare each year, this results in a large amount of time devoted to harvesting the rose petals for distillation (Guenther, E. (1952) The Essential Oils. London: Macmillan).
Additionally, because the essential oil content in the rose petals is so low, producers must choose the optimal time for harvest. The rose bushes need sun and warmth to produce the maximum amount of essential oil; roses are never as fragrant on a cloudy day as on a sunny one (Hatteschide, source, 1995). Additionally, the oil content is highest early in the morning when the flower first opens its petals, before the sun evaporates any of the oil. Consequently, roses are picked by hand each day around sunrise (Gernot Katzers, source, 2003). This process often takes approximately three hours and is usually completed between 4:30 AM and 9:30 AM, to be completed before noon. Biolandes, a private French company and major producer of rose essential oil—with plantations in Bulgaria, Turkey, Iran and elsewhere—describes their complex harvesting process: “Five thousand flowers make up one bag and experienced pickers can fill three bags in a morning,” adding that this labor occurs every morning of their 25 days rose harvest. Similar to Biolandes’ harvest, most rose harvests last between three and four weeks. (Biolandes, source, 2014).
While harvesting rose petals, workers collect them in large sacks. Once the harvest is finished for the day, the sacks are loaded into carts, sometimes pulled by horses, or onto trailers, while special care is taken not to bruise the petals (Guerilla Distiller, source, 2006). The rose petals are then transported to the distillery as quickly as possible. If the petals are not kept fresh they begin to deteriorate, and the precious volatile oil evaporates and loses quality. Thus, rose production facilities only harvest the amount of rose petals they can distill that same day to ensure freshness (Aromatherapy School, source, 2010). Typically, once they have been transported to the distillery, the rose petals are spread over cool concrete floors in the shade, where the rose petals may continue to produce rose scent until they can be distilled (International Herb Association, source, 2014).