Lavender Plants – Growing tips, cultivation and pruning
Lavender Plant Guide
Lavender, also known as ‘Lavendula’ is a very popular evergreen shrub which produces the most fragrant, beautiful flowers. It can be grown in many planting situations from a small low-growing formal hedging to potted Lavender on the patio. They will grow in most soil types as long as it is well-drained. They are relatively drought tolerant once established.
Lavender is also known for being a herb and is used in many dishes and has shown to even deter cats and they seem to dislike the smell. Hardy Lavender will live for up to 20 years but more tender varieties tend to last around 5-6 years.
There are many varieties of Lavender but the most common and hardiest is English lavender (Lavandula angustifolia) and as such makes an excellent variety for forming hedges.
Did you know Lavender contains high levels of nectar and attracts bees helping the threatened bee population!
Picture taken by Christopher Hilton
Lavender dislike water-logged soil so are best planted in well-drained poor or moderately fertile soil in full sun. It grows well in rock gardens and coastal gardens. If your soil is damp or water-logged, try adding organic matter and course grit to the soil to help improve drainage. For informal planting, space plants 45-90cm apart depending on their eventual sizes. They look well planted in groups of 3-6 plants.
Growing Lavender in pots
Growing Lavender in pots is ideal for some of the more tender varieties such Lavandula pedunculata ‘James Compton’ AGM and Lavandula ‘Regal Splendour’ as they can be placed in a green house over winter or in more sheltered areas of the garden. They are best grown in larger pots giving them plenty of room to grow in a multi-purpose or loam based compost (soil based). As they prefer well-drained soil you need to mix course grit into the soil at a rate of 70% compost and 30% grit. This will enable the lavender to have the best growing condition possible. Don’t feed Lavender too often as they thrive in poor soils, adding a sprinkle of potash can help encourage flowers, in winter they are best left fairly dry to protect them from rotting off in winter.
Growing Lavender as a hedge
Lavender makes an excellent low-growing hedge and provides a mass of highly fragrant purple/blue flowers over the summer. The best varieties for forming a lavender hedge is Lavandula ‘angustifolia’ and ‘intermedia’ because of its hardiness to frost and weather tolerance. Lavender needs to be trimmed every year after flowering, cut away a few inches of new growth ensuring you do leave a good amount of green growth as it does not shoot very well from old wood. Plant in rows approximately 30cm (1ft) apart to form a dense compact hedge.
If you are planting a hedge in soil that is clay and not well drained then try adding some organic matter or mulch and gravel to the soil to help improve drainage. Once the ground is better prepared try forming a mound to plant the lavender in so that the base of the plants are raised slightly to reduce the risk of the base of the plants getting too wet.
Lavender hedge planted in rows – Source: Wikimedia.org
As they thrive in poor soils they need very little feed but we do recommend applying potash to the soil in spring which will encourage more flowers with better colour. Do not feed with high in nitrogen feed as this will promote more growth meaning it will be long and leggy.
Try drying out the fresh flowers and using them as pourri in the home for that lovely lavender scent
Lavender needs to be pruned every year to keep a good compact shape, if they are left un-pruned then they tend to become woody and do not recover very well if pruned later as they do not re-shoot freely from old woody stems. Older plants that have been left unattended are usually best removed and a new plant planted in its place. Prune in either spring just before new foliage shoots or late summer after flowering has finished. Remove about 1-2 inches of growth leaving plenty of green foliage for the new growth to shoot from.
Hardy varieties will handle being pruned back hard so don’t be afraid to prune back a good few inches even up to 6 inches if needed.
More tender varieties tend to flower for most of summer so it is hard to know when to prune, Prune hard after flowering and then prune again in later in the season just to tidy up the plant.
All Lavender will benefit from being dead headed as the flowers finish throughout the summer, simply remove spent flowers and the flower stem back to the main growth.
The easiest and usually most successful way to propagate lavender is by taking cutting, you can either take softwood or semi-hardwood cutting in spring from new foliage or taking hardwood cutting in late autumn after flowering has finished.
To take a softwood or semi-hardwood cutting take a fresh cut approximately 2-4 inches long and remove any leaves and cut the top of the cutting just above a bud and cut just below the lowest bud. Make sure the cut are clean cuts, add a rooting hormone to the bottom of the cutting and place in a suitable pot. If you use a large pot you can put many cutting into one pot. The compost should be a mix of seed compost and shard sand (50/50). Place in a green house or cold frame. the cutting should be ready to transplant into small pots in spring.
To take a hardwood cutting do the same as explained above but take the cutting after flowering in late autumn.
How to over winter
Tender varieties need overwintering to protect them from sever frost and wet weather. Tender plants are best grown in pots, allow plants to become dry before watering, they will handle becoming dry but will not handle being wet and damp. On tender varieties we usually recommend pruning in spring. Over winter in a greenhouse or in a sheltered position again a wall or fence where they will not get too wet over winter.
Lavender Problems and Pest
Lavender are generally pest and disease free but in recent years they have been affected by the Rosemary Beetle which is easily identified by it’s metallic green with red striped shells. Their larvae and the adults eat the foliage and leaves plants looking shabby and although adults can be removed by hand the larvae is not as easy to spot. As most gardeners use Lavender for culinary reasons there are not many pesticides than can be used. One pesticide that has proven effective though and can be used on lavender plants used for cooking dishes is Provado Ultimate Bug Killer.
Rosemary Beetle on Lavender – Source: wikimedia.org
Rosemary beetle usually affects plants in the late summer and easy spring so treat at first signs of damage. Provado contains thiacloprid and is a systemic pesticide which means it goes into the plants system and when the beetle or larvae eat the foliage they take in the pesticide and controlled.