Lavender Crop Update – June 22, 2018

Angustifolia cultivars of lavender are approaching the beginning of bloom in many areas. Many fields are full of colourful buds, but bloom doesn’t begin until the flower petals emerge from the buds and open. Harvest for buds and dried bundles should occur soon after the first buds begin to open. This allows for full development of the buds, but few of the flower petals, since these turn brown once they dry and reduce the appearance and cleanliness of the buds.

The exception to this will be plants that were damaged by winter kill. These plants will often send up flowers at different stages of development (Figure 1). This staggered bloom will make it more difficult to harvest at the right time. If you harvest these plants when the first buds open, many of the stems on the plant will be underdeveloped. If you wait too long, the extra petals on the mature flowers will reduce quality. It is best in this situation to wait a little longer than normal to harvest to allow the bulk of underdeveloped shoots to develop a fully developed bud and live with a little more contamination of dried flower petals.

Figure 1. An angustifolia cultivar in 2015 affected by winter kill. Note that some flowers are in full bloom while others are not even close.

Harvest bundles by cutting them as low as possible on the stem without going into the dense leaf canopy. On average this will be between the first and second pair of leaves at the bottom of the stem. Bind bundles with an elastic so they don’t loosen as the stems dry down and shrink postharvest. Do not make bundles too large with too many leaves or the interior will begin to rot before it can dry. Harvested bundles are usually around 25-35 g fresh weight. Larger bundles are only advised if you have a system that allows for rapid drying postharvest (e.g. forced air system). Hang bundles to dry in a warm, dry location with good airflow. Avoid areas that are open to birds or rodents if the buds are to be sold for culinary purposes, since buds can be contaminated with food-borne pathogens at this stage. It is best to assume that all buds sold to the public could be used for culinary purposes.

Lavender cut for fresh bundles should be harvested when the flowers are at about 1/3 bloom (when one third of the buds on an average stem have opened or finished blooming). This allows the stem to stiffen up by harvest, preventing them from drooping postharvest. Experiments have shown that these bundles should be freshly trimmed just before being placed into buckets of shallow water. Store in a cooler at a temperature of around 10oC until sale.

Lavender harvest for essential oil extraction should wait until the blooms are past 50% opened, since research has shown that oil yields continue to increase up to this point.

Four-lined plant bugs in lavender have reached the adult stage and will soon stop damaging plants. Eggs will be laid in the green stems of lavender to hatch again next year. Garden fleahopper populations are beginning to increase and will continue to increase throughout the season (Figure 2). Look for leaves with many whitish small flecks that eventually turn brown if there is enough damage (Figure 3). There are no insecticides registered for control of these insects on lavender. Insecticidal soaps (Trounce, Opal, Kopa) applied for aphid control on lavender may also reduce populations of garden fleahopper at the nymph stage.

Figure 2. An adult garden fleahopper on a lavender leaf. Adults are tiny (2 mm) in comparison to four-lined plant bugs (8 mm)

Figure 3. Garden fleahopper damage to lavender leaves.

About Sean Westerveld

Ginseng and Medicinal Herbs Specialist, OMAFRA
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