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Lavender Grosso
Overview
Lavender Grosso is a magnificent hybrid lavender that represents the perfect marriage between English and spike lavender, creating one of the most robust and productive lavender varieties available to gardeners. This exceptional cultivar produces towering spikes of deep violet-purple flowers that can reach impressive heights, making it ideal for creating dramatic displays and substantial hedging. Renowned for its exceptional oil content and commercial value, Grosso brings professional-quality lavender production to the home garden whilst offering outstanding ornamental appeal and unmatched reliability.
Key Features
Flower Colour: Deep violet-purple, extra-long spikes
Foliage: Silver-grey, highly aromatic leaves
Height: 60-90cm (24-36 inches)
Spread: 60-90cm (24-36 inches)
Flowering Period: July to September
Hardiness: Hardy (RHS H4)
Fragrance: Intensely aromatic, commercial-quality scent
Growth Habit: Vigorous, upright, architectural
Special Feature: Exceptionally long flower spikes
Commercial Value: Widely grown for essential oil production
Growing Requirements
Soil Conditions
Grosso thrives in well-draining, moderately alkaline soil and is remarkably adaptable to various soil types. It performs excellently in sandy, chalky, or gravelly soils and tolerates poor, low-fertility conditions exceptionally well. Like all lavenders, it requires excellent drainage and will struggle in heavy clay or waterlogged conditions. In areas with drainage concerns, incorporate horticultural grit generously or create raised planting areas.
Light Requirements
Full sun is absolutely essential for Grosso to reach its full potential and produce the characteristic long flower spikes. The plant requires at least 6-8 hours of direct sunlight daily to maintain its vigorous growth habit and intense flower production. Insufficient light will result in reduced flowering and a less compact growth form.
Watering Needs
Once established, Grosso is exceptionally drought-tolerant and requires minimal watering. Water regularly during the first growing season to establish a strong root system, then reduce watering dramatically. The plant's hybrid vigour makes it more tolerant of occasional moisture than pure English lavenders, but it still performs best in drier conditions.
Planting and Care
When to Plant
Plant in late spring (April to May) or early autumn (September to October) when soil conditions are optimal for establishment. Spring planting allows the full growing season for development, whilst autumn planting takes advantage of cooler temperatures and natural rainfall.
Planting Instructions
Prepare a generous planting hole twice the width of the root ball and the same depth. Space plants 60-90cm apart to accommodate the substantial mature size and ensure adequate air circulation. In heavier soils, plant slightly proud of the surrounding soil level and add horticultural grit around the root zone to improve drainage.
Pruning and Maintenance
Annual pruning is essential for maintaining Grosso's shape and ensuring continued vigorous flowering. Prune in early spring (March) or immediately after flowering. Remove all spent flower stems and trim back the plant by one-third, avoiding cutting into old woody growth. Due to its vigorous nature, Grosso can tolerate harder pruning than many lavender varieties if renovation is needed.
Garden Design and Landscape Applications
Dramatic Hedging
Grosso creates spectacular informal hedging with its substantial size and long flowering spikes. Plant 60cm apart for a continuous hedge effect that provides privacy, wind protection, and months of stunning floral display. The uniform growth habit makes it excellent for formal landscaping applications.
Statement Plantings
The impressive size and architectural form make Grosso perfect for creating focal points in large borders or as specimen plants in key garden positions. Use singly or in groups of three or five for maximum impact in spacious garden settings.
Commercial-Style Plantings
For gardeners inspired by the lavender fields of Provence, Grosso is the ideal choice for creating authentic lavender field effects. Plant in rows or drifts for a commercial-style display that's both beautiful and practical for harvesting.
Large Border Integration
Grosso provides excellent structure and backbone in large mixed borders where its substantial size can be properly appreciated. Use as anchor plants or repeated elements to create rhythm and continuity in extensive planting schemes.
Harvesting and Practical Uses
Essential Oil Production
Grosso produces exceptionally high levels of essential oils, making it the preferred variety for commercial lavender oil production. Home gardeners can harvest the intensely aromatic flowers for homemade essential oils, with yields significantly higher than most other lavender varieties.
Large-Scale Cut Flower Production
The extra-long stems and abundant flower production make Grosso excellent for cut flower use. Harvest just as buds begin to open for maximum fragrance and longevity. The substantial stems create impressive fresh arrangements and are particularly valuable for large-scale displays.
Dried Flower Excellence
For dried flowers, harvest when approximately half the flowers have opened. The long spikes dry beautifully whilst retaining much of their colour and fragrance, making them ideal for wreaths, large dried arrangements, and commercial craft applications.
Culinary Applications
Grosso's intense flavour makes it suitable for culinary use, though it should be used more sparingly than English lavender varieties due to its stronger taste. Excellent for lavender honey, baking applications, and flavouring syrups or preserves.
Wildlife and Environmental Benefits
Despite flowering later in the season than English lavenders, Grosso provides valuable late-summer nectar when many other flowers are declining. The abundant, long-lasting blooms support bees, butterflies, and other beneficial insects during the crucial late summer period when food sources can be scarce.
The substantial size and dense growth habit provide excellent habitat for beneficial insects and small wildlife, whilst the natural deer and rabbit resistance makes it ideal for larger plantings where browsing pressure might be significant.
Container Growing Considerations
Large Container Requirements
Due to its substantial size, Grosso requires large containers (minimum 50cm diameter) for successful cultivation. Use heavy, stable pots that won't topple in wind, and ensure excellent drainage with plenty of crocks and gritty compost.
Patio and Courtyard Use
Where space permits, Grosso makes a dramatic container specimen for large patios
Buying Shrubs from Jacksons Nurseries
At Jacksons Nurseries we sell a variety of shrubs both evergreen and deciduous with a variety of flowering times throughout the year. At certain times of the year our shrubs you buy from us may not look like the images shown on our website when deciduous leaves have fallen, the shrub has finished flowering or has been trimmed back.
Some leaves on evergreen shrubs can be damaged in winter by frost or harsh winds but in spring new leaves will readily replace those damaged. This is quite normal on many evergreen varieties and is preferable to plants grown with excessive protection that show cold shock once planted out and establish less satisfactory initially.
Availability: Stock availability figures are provided as a guide only. There is a delay between orders being placed and the plants being gathered by our pulling team. During this time it may be possible for a member of the public to purchase these plants from our Garden Centre, while this is rare it is a possibility and we will notify you of any problems as soon as possible. This figure may also include plants that have not yet be flagged as unsaleable.
Pre-order: Pre-order times are given as a guide only and may vary dependent on the growing season. Orders containing Pre-ordered products will be shipped as a single order when all items become available. Large orders may be part shipped, please contact us on 01782 502741 or email sales@jacksonsnurseries.co.uk.
* Please Note: Shrubs in 20 litre pots and above might require a pallet delivery starting at £79.99 per pallet. Depending on the exact pot size and height it may be possible to get approximately 5 plants per pallet at no extra cost. The maximum height we can dispatch on a pallet is 2.0m, this includes the height of the pallet and pot.
Shrubs are deciduous or evergreen woody plants, and often provide fragrant flowers, berries and foliage. They are good for structural framework, and they can provide a wonderful shelter and food source for wildlife.
Planting and Conditions
Container grown shrubs can be grown at any time of year. It is a little known fact that shrubs planted in the autumn and winter will be easier to look after than those planted in the spring and summer, because they will have time to establish and become hardy in the cooler months.
Plant the shrub at the same depth as it was in its original pot. Planting too deeply can result in root and stem rot.
One of the biggest causes of death in new shrubs is drought stress, so keep it well watered until it’s established.
Make sure you loosen the soil prior to planting. Most shrubs are tolerant of most soil types as long as it is fairly well draining.
Most shrubs will grow happily in containers, but they will be much more demanding on feeding and watering than shrubs in the ground would be. They will also need potting on every couple of years so that they don’t suffocate or become stunted in their pot.
Aftercare and Pruning
Once established, shrubs generally do not require much water. However, at first they need careful, frequent watering and should not be left to dry out.
Shrubs in the ground are generally not demanding and in most cases, annual feeding with general purpose fertilizer will suffice. Shrubs in containers may need more feeding; usually from early spring until late summer.
Shrubs also benefit from mulching in order to supress weeds, conserve moisture and provide vital nutrients. Mulch also greatly improves soil conditions. Shrubs can be mulched in late winter, after fertiliser has been applied, but it can be mulched through autumn to late spring as long as the ground is damp.
All shrubs benefit from dead-heading once spent flowers become apparent. Rhododendrons and Lilac especially benefit from the removal of dead flowers.
Some shrubs may show signs of reverted growth or ‘sporting’. This is where random shoots of different leaves associated with the plant’s parentage begin to appear. Most commonly this is where plants with variegated leaves sprout pure green growths instead of variegated ones.
To control reversion, remove reverted shoots promptly to discourage them. Reverted shoots are usually much more vigorous than the variegated ones, and thus should be completely pruned out and cut back into wood containing variegated foliage.
Potential Issues
Although shrubs are usually very robust garden plants, they can sometimes start to decline with no apparent or obvious reason.
This will start with browning leaves, which could indicate plant stress due to lack of water or waterlogging, an establishment failure or, in the worst case scenario, honey fungus. Another cause of leaf browning is a high salt content in the soil. This could be a natural occurrence, especially if you live near the ocean, or it could be from over fertilisation.
To remedy a high salt content, cut back on fertiliser and step up your watering regime for the next few weeks. If you live by the ocean, this will be harder to remedy—but stepping up your watering will help to wash some of the salt away all the same.
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