Hand harvesting lavender

The traditional method of harvesting lavender flower is by sickle. Between 2003 and 2010 this was the primary method of harvesting at Snowy River Lavender. While it can be said that approaching a paddock of lavender in full flower, sickle in hand, is somewhat daunting, there is nevertheless a type of romance to it. There is the camaraderie, the sheer sensual pleasure of being up to ones arm pits in lavender flowers, the beauty of the insect world, the excitement of filling a truck with flower and riding high on the load to the distillery. This said, it is also hard work in the summer heat and it requires a lot of good will from family and friends because if there is one truism of harvest time, it is ‘many hands make light work’. As we pressed towards a commercial scale increasing our acreage under cultivation, the romance had to give way to the pragmatics of the higher levels of production. We still do some hand harvesting, but the bulk of flower is now gathered by the machine

Gathering drought effected lavender flower

Drought effected lavenders have short stems and are difficult to harvest efficiently with a sickle. The drought of 2009 saw us devise the hedge trimmer and sling method for hand gathering the flower. The plants shown in these photos are the same shown above being sickle harvested a year before. This highlights the distinct effect on the flower of a dry season, not surprisingly the essential oil of these dry years is intensely sweet and high in esters.

MACHINE HARVESTING LAVENDER

Since 2009 our primary means of harvesting is by way of a tractor mounted machine from Clier, a French agricultural engineering company located in the lavender growing region of Provence. Snowy River Lavender is definitely not a broad acre farm with many different sized plantings dotted opportunistically around our steep property. Thus in choosing a harvester the hilly terrain and the tightness of some small patches were important issues to us. We also wanted a harvester which showed respect to the plants and flowers being harvested, meaning we wanted a harvester which cut the flower whole without mulching, and had the sensitivity and scope of function to be able to harvest plants of varying size. In this respect Clier has produced a beautiful machine with enormous scope of operability and while it is not an easy machine to use in our conditions we have however people in our ranks with the necessary machinery skills to operate this harvester with efficiency in challenging situations.

THE MECHANICS OF GATHERING FLOWER

The harvester straddles one row of lavender cutting the row to its left as it slowly moves along. Long yellow arms to either side of the cutting deck lift slightly the splayed bushes so that the side flowers can be cut. Cut flower then moves up a specially designed conveyor into the hopper.

Cut flower is transferred to the distillery via truck. Until 2012 moving flower from the hopper into the truck was largely manual. Flower was conveyed out onto a tarp then swung into the truck. In 2012 the farms bobcat skid tractor found another use and is now used to perform the transfer making it physically easier for all involved.TRANSFERRING FLOWER FROM THE HARVESTER

Timing harvest for essential oil production

Timing the harvest is a key determinant in achieving character, quality and yield in our essential oil production.  The stage of flowering is pivotal in this decision with nectar feeding insects such as honeybees central in how the timing of the flowering process plays out.  However, it must be said that picking the right time to harvest a cultivar in a farming situation is not only about there being an ‘ideal’ time to take a flower but also about logistical issues such as the length of time it takes to remove the flower from the field and when we can give that flower still time.  Farming is usually a compromise between these two levels of consideration and seeking to maximize both to produce oils and hydrosols of premium quality.

Stages of flowering and harvest

Lavender is a complex flowering form. The spike, often taken for the flower, is actually a collection of many calyxes each of which buds and flowers across the summer season.  When the flower opens it will be visited by a bee, or insect, which triggers a hormonal reaction, the onset of seed set and within a couple days the flower withers and dies (unvisited flowers will last 10 -12 days before it dies, Somerville 2000). This flowering of the lavender spike is not a unitary process where all calyxes flower at once, but one staged over a number of weeks and at any one time during this season all these stages of flowering can be found on the spikes. There are, however, points across the flowering season where different stages of flowering dominate the spike. The greatest depth of colour in the lavender field is when the flowering stage is dominant, with colour diminishing as the percentage of the spike favours spent flower.

 

New Zealand scientist Noel Porter has done important research into the qualitative contribution of flower head maturity to the aroma and chemistry of the oil produced.  His findings are summarised below:

1. Fresher more subjectively accessible fragrances come from early harvested flower (33% withered, 33% flower and 33% bud).
2. More complex and deeper oils from the later harvested spikes (33% flower, 67% withered).
3. Totally spent flowers produced subjectively less attractive oil.
4. These subjective assessments were also backed up in the phyto-chemistry, with slightly higher levels of the fresher compounds such as the esters and 1-8 cineole in the earlier harvested flower.
5. Porter, N. ‘The Influence of Flower Head Maturity on Oil Quality’ - Noel Porter & Associates, Christchurch, New Zealand: TALGA Conference Proceedings, Launceston Tasmania 2011

Bees and lavender

Anyone visiting a lavender field in mid-summer can be in no doubt about the important relationship between lavender and bees. The field literally hums with a synergy of activity which benefits both these key participants. French researcher, Barbier, working in the late 1950 and early 1960’s, found a significant link between the hormonal reaction caused by bee activity and an increase in essential oil production in the lavender floret or calyx. Thus while the essential oil is not in the lavender flower but in minute sacs with the appearance of glistening hairs on the calyxes, the flower as the plant’s primary interface with nectar feeding insects triggers hormonal change with repercussions in the amount of essential oil the calyx produces.

Key points from Barbier’s (1950 – 1960) research into the effects of bee activity on the essential oil yield of lavenders and lavandins.

1. There is a significant link between the hormonal reaction caused by bee activity and an increase in essential oil production in the lavender floret or calyx.
2. For the sterile lavandin, the increase was a 16 – 20 % higher yield, attributed to the lavandin’s inability to produce seed and hormonal activity instigated by the bees fed directly into the formation of more oil.
3. For the fertile lavender, there is an increase in yield but not as high as for the lavandins, however it was found that there was a 15 day window after the bee’s visit to the flower when the oil production peaked in the calyx after which the oil yield was diminished. It is assumed seed formation then took over as the primary function of the floret.
4. (Barbier cited in Somerville 2000) Somerville, D.  ‘Bees and Lavender’. Lavender Australia Conference Proceedings, Wagga Wagga 2000. 

Timing the harvest at Snowy River Lavender

Barbier’s research argues that yield is maximised through bee activity however the fact is that the flowering of lavender is not synchronised but staged over a number of weeks before the spike finishes its capability of blooming.  This means there is no clear cut point at which you can say, ‘this is when all the flowers are out the bees have visited we will take them now’, we will have a great yield. This is where reading the stages of flowering as a qualitative indicator, such as discussed by Porter, becomes useful in how harvest is timed. The reality is that choosing when to harvest is a finely balanced decision which must be worked towards optimising both yield and quality.

At Snowy River Lavender we seek out the point where a particular field of lavender just passes the height of its colour.  In other words, we seek to harvest when the balance has just shifted towards spent flower, the point when more than half the flowers are newly spent, usually between 60 and 70%.  This means there is still some freshness (flowers and buds) to the harvested spike but bee activity has been significant.  The oils we produce do tend toward a bright but resonant complexity and we have adopted this as our signature essential oil character. Importantly this general rule means we leave the flower in the field for as long as is reasonable for the quality of oil desired because as beekeepers we like them to have a fair go as well.  Machine harvesting means once the harvest call is made, flower can be brought to the distillery rapidly and the desired character preserved as essential oil and hydrosol.