Winter Damage

The lavender crop should be fully green now, making any winter damage obvious. Plants without any signs of green growth, even at the base of the stems, are likely dead and will need to be replaced. Those plants with buds growing from the base of the stem should be pruned back to let more light penetrate to the centre of the plant. It gets a bit more complicated for plants with less severe damage. Click here for tips on dealing with winter damage. As a general rule, you can always cut dead branches off the lavender without affecting the rest of the plant. Any other pruning should be done with care because it could affect the bloom.

Frost

Now that plants are greening up and flower buds will soon be visible, plants are more susceptible to frost. The susceptibility increases as the buds become more exposed. An extended cool period is in the forecast, which could bring the risk of frost. Keep an eye on the forecast and consider re-covering plants with row covers if needed. At the very least, consider covering the plants that you cannot afford to lose (e.g., display fields for agritourism).

Bloom Time

Temperatures so far this spring have been normal to slightly above normal. If temperatures remain normal, bloom time should be relatively normal this year. Last year, bloom time was about a week early. A hard pruning or severe winter damage often results in a delayed bloom because extra time is required for the plant to sprout secondary buds. Any secondary buds will still bloom, but bloom could be staggered over a longer period, making timing harvest for buds and bundles more challenging on these plants.

Four-Lined Plant Bugs

Now is the time to start scouting for four-lined plant bugs. Look for spots and curled leaves at the tip of the stems near the growing point (Figure 1). If you see extensive damage, consider an insecticidal soap application while the bugs are still small. While there is nothing registered for control of four-lined plant bug directly, insecticidal soaps applied for aphid control in lavender will likely also suppress four-lined plant bug, but only if the nymphs are still small. Click here for products registered for aphid control on culinary lavender. Some of these products may be acceptable for organic production. Consult with your certifying body to ensure products are permitted before applying them.

Figure 1. Early damage to lavender shoot tips caused by four-lined plant bug feeding.

For more information on identifying and managing four-lined plant bug in lavender, visit the four-lined plant bug profile in the lavender module of Ontario Crop IPM.

For those new to farming, growers wishing to purchase commercial pesticides like insecticidal soaps will need their Grower Pesticide Safety Course Certificate (https://www.opep.ca/farmers/grower-pesticide-safety-course/). Be proactive to ensure you have this in place before you suddenly need to control a major pest outbreak. Commercial growers (those selling their crop) need to use commercial pesticide formulations (i.e., purchased from farm supply outlets) both because of regulatory requirements and because domestic products would not be economical.

Fertilization

There is a myth out there that lavender does not need fertilizer. Lavender is a plant, and therefore needs all the nutrients that any other plant needs. My research has shown that yield is maximized with 80-100 kg/ha of nitrogen applied every year, split among two or three applications from May to early August. Lavender also likely has average requirements for phosphorus and potassium. Fertilization of these nutrients should be based on a soil test. Click here for information on how to determine fertilizer rates in lavender.