Most people do not see gardening your own food as saving energy. They see it as healthy and even self reliant. It does save a huge amount of energy. First and foremost there are no transportation costs to your vegetables. If you use a lot of fertilizer then that changes some but the cost of an avocado from Mexico is huge. Second, you are not driving heavy equipment like at a large vegetable farm. You should see the fertilizers, pesticides and herbicides they use.
Rosemary is one of those plants that not only smells good, it tastes good and looks good too. When I say taste, I mean as a flavoursome herb so don’t start chomping on a random stem and expect it to fill you with culinary delights – because it won’t!
Be that as it may, rosemary plants are fantastically popular and are often found in gardens as a specimen shrub or informal hedging. Evergreen – and tolerant of most soils so long as the drainage is good, they will even put up with most of the weather that Britain can throw at it despite is warmer origins of the Mediterranean and Asia
If you are using it as a specimen plant then you can prune after flowering. Otherwise, August to September will be the best months.