Ocimum kilimandscharicum x Ocimum basilicum 'Dark Opal'
Tradescantia pallida in background
This is a big shrubby perennial basil growing to over a metre in height which has matte green leaves coloured on the reverse side a dusty purple. It originated in an American herb garden as a chance seedling and is a sterile hybrid, not setting any viable seed. It flowers for most of the year and is one of the best bee attracting plants that I have grown. As basils tend to be shallow rooted it is advisable to stake this variety as it is very susceptible to blowing over in a strong wind. Mine did in August and though it kept growing after being propped up I eventually hauled it out. I took cuttings which struck fairly readily and now the new plants are off and running into flower with the bees back in force. Plants can also split down the middle often under the weight of all the flowers which elongate and keep on going seemingly forever. A once over with hedge shears is a good way of keeping a trim and compact bush. You could do this in stages if you are worried about depriving the bees of some food. Plants require very little water and will tolerate light frosts.
There is a bit of debate around about the edible qualities of the perennial basils (there is a plain green type as well). It does contain quite a bit of camphor oil which makes it pungent so err on the side of caution when using in the kitchen.