Feeding Lavender Plants and Hedges
Generally speaking, Lavender plants do not need much in the way of feeding, if you add more than a small amount of general fertiliser they will make masses of leafy growth and be likely to flop just as the flower spikes start to lengthen, spoiling the effect.
Instead, we would recommend nothing more than a modest feed with a high potash fertiliser in late Spring.
As already mentioned, Lavender plants do not benefit from mulching. Better to leave the soil bare and dry – the conditions they love!