Providing care advice to the gardener is always welcome and good policy. Once established lavenders thrive on neglect except for their annual prune, which is the subject of great confusion and is explained in some detail.
Lavenders require well-drained neutral to alkaline soil, although L. stoechas subsp. stoechas (which always grows in acid soil in the wild) and to a lesser extent L. x intermedia, can thrive in a slightly acid soil. In heavy soil adding grit at the rate of 25 kg/m2 when planting will improve drainage as will planting on a slight mound. Wet soil in winter can have a particularly deleterious effect on half-hardy and frost-hardy lavenders and it is this additional wet soil, rather than just a frost, that is more likely to kill these plants.
Plant lavenders in a sunny position or at least where they are in the sun for most of the day. Do not grow them under a leaf canopy. Tender, half hardy and dwarf lavenders are ideal for 30-40 cm terracotta pots and look particularly impressive as patio plants.
Space lavenders 45-90 cm between plants for informal plantings, depending on their eventual size. Planting in groups of three is very effective. For hedging, dwarf lavenders to 60 cm are best planted 30-40 cm apart. Tall lavenders over 60 cm may be planted 40-45 cm apart. For a formal hedge use the same lavender.
Ensure the soil and site are as described above. Moisten the plant compost, but do not waterlog. Dig a hole and add a dusting of bone meal to the hole and the soil removed from it and mix together. Fill the hole with water and allow to drain away. Place the plant in the hole and fill to the level of compost around the plant stem. In dry conditions water the soil around the plant, but do not over water. Be attentive to lavenders in the first few weeks after planting, especially if the weather is dry as the compost in which the plant was originally potted will dry out very quickly.
Use a mix of one-third each of a soilless compost, John Innes No. 2 or 3 and coarse grit. For feeding, add slow release fertiliser at the recommended rate. One application should last all season.
This should be unnecessary after establishment, except plants in pots! Feeding
Little feeding is required, although a sprinkling of potash 35 g/m2 or rose fertiliser 60g/m2 around the base of plants in spring will encourage more prolific flowering and improved flower colour. Adding bulky manures may well lead to sappy growth and few flowers.
To use lavender for drying and pot-pourri, harvest just as the flowers are opening and hang upside down in bunches in a dry dark room.
Tender and half-hardy lavenders (and frost-hardy lavenders grown in pots) should be kept under glass in light, airy conditions. These plants need very little water from November to February. Wait until the pot is noticeably lighter or even until plants start to droop and then water only on top of the compost. Never water over the foliage in winter. These plants suffer in still, moist
This is often the most misunderstood aspect of growing lavender and needs some clarification. It is a very important task that demands a strong constitution, because generally the harder lavenders are pruned, the longer they will last. They require different treatment according to hardiness.
Hardy lavenders which normally flower just once, may have a weak second bloom after pruning. To keep them in shape they should be pruned to just 22 cm immediately after flowering. It is particularly important to be severe with the tall growing lavenders, even if you have to sacrifice some late flowers. If there is a reasonable number of small shoots visible below where you cut they will grow strongly even from old wood, but if there are no shoots below the cut lavender will die. If pruned at the correct time new growth should leave lavenders overwintering as leafy hummocks.
It is possible to save old gnarled lavender, which has much bare wood topped with a mass of growth. Prune to within 10 cm of the bare wood to see if this encourages shoots to sprout further down the plant. If it does, then when next pruned do the same again, until the new growth starts at ground level.
Frost hardy lavenders, typically have 'ears' and because they flower from spring to autumn it is difficult to know when to prune. A general guide is to prune hard to 22 cm immediately after the first flowering. Dead-head for the rest of the flowering period, with possibly just a light trim in early September.
Half-hardy and tender lavenders are the toothed and trident-headed lavenders that flower almost continuously. Generally, dead-head throughout the year with the occasional severe prune, as outlined above, to keep especially the more vigorous forms in shape. After a severe pruning keep the compost quite dry until a moderate flush of new growth appears.
Was this article helpful?