Soil and Site - We are always asked how to grow lavenders. Lavenders like well-drained soil in a sunny site that receives sun for most of the day. Lavandula angustifolia prefers alkaline soil which will help extend its life whilst Lavandula stoechas subsp. stoechas and to a lesser extent Lavandula x intermedia, can thrive in slightly acid soil. Lime maybe added to acid soils where necessary.
In heavy soil, mix in grit when planting to improve drainage and plant on a slight mound. Wet soil in winter can have a terrible effect on half-hardy and frost hardy lavenders and it is wet soil, rather than frost that is more likely to kill these plants.
Spacing - Lavender angustifolias and x intermedias make excellent hedges. Plants should be spaced at 40cm for angustifolias and 45cm for x intermedias. For planting in borders we would suggest groups of 3 planted 60cm apart.
Planting and Watering - Follow the instructions on the reverse of the colour label when planting your Lavender. If your soil is not free draining add 1/3 of Horticultural grit by volume to the soil. Be careful not to overwater plants in dry periods as Lavenders prefer to be on the dry side rather than waterlogged. Avoid watering the foliage wherever possible and try to water in the morning so that the foliage can dry before night time. Established Lavenders do not need watering even in droughts.
Plants, especially stoechas subp, stoechas types lend themselves to being grown in pots as plants maybe be given some winter protection from wet and cold by moving under cover. Keep plants in pots dry throughout the autumn and winter.
Hardiness - Lavandula angustifolia and x intermedia are hardy in most of the UK and can withstand up to -15ºC. Most losses overwinter are due to the lack of drainage rather than cold. Lavandula stoechas subsp. stoechas are less hardy and will survive some frost- to between -5ºC and -10ºC, but as with angustifolias are more likely to be killed by wet and frozen roots. Therefore, the more free draining your soil the better the chance of winter survival.
Feeding - Lavenders are not hungry feeders so avoid giving them manure or Nitrogen based fertilisers. A sprinkle of Sulphate of potash or watering with Tomorite can encourage flower quantity and colour.
Pruning - Lavender angustifolia and x intermedia Prune immediately after flowering, cutting the flower stalk back hard into foliage below its base- 20-30cm above the soil. Make sure you leave 3 pairs of leaves below your cut as this is where the re-growth will emerge from. If you cut into bare wood you may get no re-growth.
Lavender stoechas subsp. stoechas -These tend to flower most in late spring and then repeat flower through the summer. You have to sacrifice some flowers in order to keep your plants in shape and this is best done after the main spring flowering. Cut back into the stems 20-30cm above the soil, ensuring you leave at least 3 sets of leaves below your cut. Continue deadheading over the summer and into autumn and a light prune in August may also provide additional shape before the winter.