Lavenders will grow in these low concentrations, but will take off if given plenty of nitrogenous fertilisers, provided there is ample Calcium and Magnesium. Thus we recommend that lavenders should be given annual feeds of Calcium and Magnesium. We also give regular feeds with high nitrogenous fertilisers. There are several on the market that also have some Calcium included. An annual application of potassium three to four months prior to flowering will improve flower quality.
Lavenders also grow well in very dry conditions and are quite drought tolerant.
This does not mean that they don t like water, but require it supplied under well drained conditions. These can be obtained by potting into a very open mix or planting out into raised beds. Regular watering, preferably not on the foliage will also increase growth rate. The other two requirements of lavenders are good air movement and high light levels. Don t get light levels confused with temperature.