Growing Grosso Lavender Plants
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Why Grosso
Grosso lavender (Lavandula x intermedia 'Grosso') is a popular variety known for its fragrant, large purple flower spikes and robust oil content. At Great Lakes Lavender Farm, we cultivate Grosso lavender due to its hardiness and versatility, making it ideal for gardens and commercial use.
Ideal Growing Conditions
Grosso lavender thrives in well-drained soil with a neutral to slightly alkaline pH. It prefers full sun exposure for at least 6-8 hours daily. Good air circulation helps prevent diseases, which is essential for healthy growth.
Planting Grosso Lavender
Plant Grosso in spring once the ground warms, or in early fall so the roots can settle in before winter. Space plants about 2 to 3 feet apart to allow adequate airflow and room for growth. When planting, ensure the crown is at soil level to avoid rot.
Watering and Fertilization
Lavender is drought tolerant but requires consistent watering during the establishment phase, approximately the first season. Afterward, deep but infrequent watering encourages deep root growth. Use a balanced, low-nitrogen fertilizer sparingly to avoid overly lush foliage that can reduce oil concentration.
Pruning Practices
Regular pruning is key to maintaining a compact shape and promoting vigorous flowering. Prune Grosso once a year, right after harvest in mid to late summer: take off about a third of the green, leafy growth and leave 2 to 3 inches of green above the woody base. Never cut into old brown wood, which rarely grows back, and avoid hard pruning after early September so new growth isn't caught by frost.
Harvesting Lavender
Harvest the flowers when the buds are fully formed but before they are completely open. This timing ensures maximum fragrance and oil yield. Cut the flower stems in the morning after the dew has dried for best quality.
Managing Common Pests and Diseases
Grosso lavender is relatively resistant to pests but watch for aphids and spittlebugs. Good cultural practices reduce disease risk, including root rot and fungal infections. Avoid overwatering and improve soil drainage if necessary.
Overwintering Tips for Great Lakes Regions
In Great Lakes winters, drainage matters more than mulch. Keep heavy mulch away from the crown, where trapped moisture can cause rot; in windy, exposed spots, a breathable cover like evergreen boughs laid over the plant after the ground freezes can help. Skip late-season pruning, and consider raised beds or mounded rows if your soil stays wet.
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