This is part of my rosemary hedge which is a few years old now. My original intention was to completely surround half a bed and grow carrots there every four years, but I have never finished it off. Rosemary repels carrot fly which almost always sniff out an unprotected crop. I was told it is difficult to grow so I thought about its home territory -Mediterranean hillsides- and prepared a stony subsoil for its roots to penetrate. I collect stones from the plot specially, as they surface, keep them until I need them, putting them into a trench about a spit (spade) deep.
One year I hastily ripped out the corner of the hedge trying to save the rest of the hedge from disease. Unfortunately I worked out later that the scarred foliage was as a result of intense cold on the corner. It is frost hardy but only down to -5° C.
Flowering before pruning
In medieval times they thought diseases spread by smells (well, they were nearly right) and so tried to counteract the plague by filling braziers with pungent substances such as rosemary to purify whole streets at a time. Individuals also carried around a bag of aromatic substances like rosemary and sniffed at it constantly to avoid catching the plague. (well it worked sometimes).
Rosemary and sage are reputed to be mutually beneficial, but I tend to shift the sage around so it can be close to the brassicas.
To get a decent bush of it I cut it right back in spring to about half a metre. I always intend to let it flower, but I usually tire of waiting and give it a good hacking. Last year having kept a bit for the kitchen I made a lovely fragrant carpet on the adjoining walkway which obligingly kept it weed free this summer.
Each winter I extend this idea by using the decapitated Asparagus ferns, and the prunings from the Wild Rocket, which, being a perennial, I cut right back to within 15cm or so of the ground. But nothing can compete with the scent given off from the freshly cut rosemary.
I have managed to grow them from seed one year for the first time and the tiny seedlings survive the winter, but they do not readily germinate. I suspect that this is because the seeds need to be damp to germinate but the plants basically do not like wet conditions. By far the most successful way of propagation is to take cuttings. This is done in September, by gently pulling back a piece of fresh growth from the stem so that a “heel” forms. If you stand this in water roots develop. The one in the photograph shows how successful this can be. Each year I successfully add a few new plants but cuttings take time to develop, both in potting them up and in waiting for them to mature. Like the propagation of fruit bushes it does work but it requires patience.