Article by David Marks
Lavenders are evergreen shrubs growing to between 35cm / 1m (14in to 3ft) high and a slightly larger spread. They are grown for their flowers, foliage and scent. Their ability to resist drought make them ideal for dry parts of the garden. It's difficult to kill an established lavender bush through neglect but they last longer, and look at their best, with a good annual prune.

Use the checklist below to decide if Lavender is the correct plant for you and your garden:

• English lavender is hardy down to -12°C. French lavender is far less hardy, assume it is hardy to around -2°C, possibly a couple of degrees lower if the soil is very free-draining
   
• Grow equally well in open ground and containers
   
• Flowers are produced for about 6 weeks during from early June to mid August, the exact timing depends on the variety. The foliage is attractive all year round.
   
• Tolerate periods of drought especially when grown in the open ground. Their leaves are thick skinned and retain moisture well.
   
• Tolerate neglect well mainly because their nutrient requirement are low.
   
  
• Lavender needs a light soil (clay will need improvement) which is not rich in nutrients.
   
  
• They are suited for growing in full sun to give their best but will tolerate a small amount of shade.

DIFFERENT TYPES OF LAVENDER

This page is primarily concerned with growing hardy lavender in the UK but there are several types, some hardy and some not so hardy. The key types are listed below:

ENGLISH LAVENDER
This includes Lavandula angustifolia and Lavandula x intermedia. Both are hardy down to -12°C, even a few degrees lower if not in an exposed position, so will grow in all parts of the UK. The foliage is from silver grey to dark green and the flowers are generally shades of lavender colour although there are white and pink flowered varieties.

FRENCH LAVENDER
This Latin name for these is Lavandula stoechas. The flowers are more flamboyant compared to English lavender and with some dead-heading, they can last from late May to mid September. They are however, not so hardy, withstanding temperatures down to -5°C. All lavenders need the correct soil conditions but this is critical for French lavender if it is to last through the UK winter. Not a plant for cooler areas.

TENDER LAVENDER
There are several other types of lavender which are either half hardy or tender. These should be treated as annual plants in the UK because frost will kill them.

HOW, WHEN AND WHERE TO PLANT LAVENDER

Top quality lavender plants need top quality soil preparation. Lavender originates from the warm climates of Southern Europe and it is best suited to ground which drains easily and is slightly low in nutrients. It does best on soil which is slightly alkaline to neutral, chalky and / or stony ground is best. To improve soil which is not in the ideal condition, add lots of well-rotted organic matter and horticultural sand to help drainage. 

If you have a clay soil then prepare the ground as described above but also mound up the soil so that it drains well. Lavender is ideal for planting in windy coastal areas, it shrugs off the wind without a problem. It is best suited to a full sun position which will extend its life and help to stop it going woody and bare at the base.

Individual plants should be spaced 1m / 3ft apart to allow them room to grow to full size. Lavender hedges should have individual plants closer together, about 40cm / 16in apart.

Lavender is best planted in mid to late May time when hard frosts are unlikely, the ground is warming up but still contains moisture. Dig a hole slightly larger than the rootball, sprinkle in a handful of long-lasting fertiliser such as blood, fish and bone and work it into the ground.

Tap the plant out of its pot and place it into the hole. Adjust the depth of the hole so that the plant is to the same depth as it was in the pot. Fill in around the rootball and gently firm down the soil around the lavender plant. Water in well.

CARE OF LAVENDER

The only time to water your lavender if is the plant starts to wilt. In the UK there are very few occasions when it will need more water than natural rainfall provides. The big danger is not under-watering but over-watering. Lavender hates soggy ground.

The same goes for feeding; in almost all cases lavender will be more than capable of extracting sufficient nutrients from the surrounding ground. Leave them well alone is our advice.

The one care task essential for lavender is to prune it once a year. If this is not done the plant will quickly become woody and bare of foliage at the base. Once this happens there is very little that can be done other than buy a new plant. Lavender rarely sprouts new shoots from old wood.

The best time to prune is immediately after the plant has finished flowering normally late July to August. Don't prune in the first year after planting. To prune, simply cut the top 15cm / 6in off all round the plant. Pruning with a pair of secateurs will take about 10 minutes per plant.

LAVENDER PEST, DISEASES AND PROBLEMS

Lavender are very healthy plants and rarely suffer from pests or diseases. The following pests and "conditions" do occasionally affect them. For those of you (like us) who suffer from slugs in the garden, lavender is exceptionally good news! Slugs don't like them and stay well away.

CENTRE OF PLANT FLOPS OPEN
When this happens the side branches flop down leaving the woody centre of the plant open. This is caused by either the soil containing too many nutrients or too much water. Lavenders naturally grow in dry ground which has low levels of nutrients, and when these conditions are reversed, they can grow too much weak and leafy growth.

The solution is to do nothing! Do not feed and do not water. Prune the plant slightly harder than normal after flowering (but not into woody growth) and hope that the nutrient and water level will fall down the next year.

CUCKOO SPIT
In the joints between stems you may see what looks like frothy blobs of liquid. This is caused by froghoppers and capsid bugs. It does no harm at all and can be ignored. If you want to remove it then wash off with water but don't waterlog the surrounding ground.

ROOT ROT
This is identified by the plant being in poor health and eventually dying. It is caused by too much moisture at the roots causing the roots to rot and be unable to support the growth above ground. Unless you have been watering your lavender then in reality it means that the position is too moist to successfully grow lavender unless the surrounding soil is significantly improved as far as drainage is concerned.

LAVENDER SUMMARY

Below we list the key strengths and weaknesses of hardy lavender.
 

HARDY	(to -12°C)
CLAY SOIL	No
SANDY SOIL	Yes
DRY SOIL	Yes
SHADE	No
EVERGREEN	Yes
EASY CARE
SMALL GARDENS	Yes
POT / CONTAINER	Yes
FLOWERING
FLOWER TIME	End June to early August

Other "easy-care" shrubs in this series include Choisya, Hebes, Mock Orange, Lilacs, Potentilla and Rose of Sharon (hibiscus syriacus). Click the link below for the full list of shrubs we have reviewed.