I run a natural pet products company and we use a lot of essential oils in our products. We have a commitment to "Made in New Zealand" and source as much of raw material locally as possible. Finding it impossible to buy NZ produced pure Rosemary Essential Oil in commercial volumes came as both a surprise, and a disappointment.
Rosemary is such an important medicinal and culinary herb it seems that there is a great opportunity for good quality locally grown product. We'd certainly put our hands up to buy essential oil from an NZ grower in kilo lots. (Commercial trading of essential oils is by weight rather than volume).
Throughout history Rosemary has been used to treat a wide variety of ailments - from indigestion, depression, muscle spasms, headaches and nightmares. Rosemary essential oil also has antioxidant properties. I use it as one of a number of essential oils in a natural flea repellent that has been developed for dogs as an alternative to chemical treatments.
In olden times Rosemary was thought to have protective powers to help ward off evil spirits. It is said that the Virgin Mary draped her cloak over a Rosemary bush when she was resting and the white flowers turned blue. Rosemary also has a strong association with love - traditionally worn by brides in a headpiece and planted by newlyweds as a symbol of their strong union.
In our garden we have several Rosemary hedges - originally planted to provide structure and shelter in the early stages of the garden development. It's ideal used this way because it is so fast growing, yet so useful as well. I still enjoy the smell of brushing against the plants or picking a sprig and rubbing it in my hands.
There are dozens of different varieties available, including prostrate or groundcover which will drape over walls and rocks. I personally prefer the stronger more upright varieties that grow to over a metre high and make such great structural hedges (Rosmarinus officinalis).
Whatever variety you choose, it's really simple to propagate:
" Using sharp secateurs cut a piece with some fresh growth on it - around 10cm - and push it into friable seed raising mix. This can be done anytime from late spring to mid autumn.
" Once cuttings develop roots, transplant them into pots so they will be ready to plant into the garden in spring.
" If you are a little bit disorganised (like me sometimes) and haven't sorted out the seed raising mix, push a piece into the ground where you want it to grow. Your strike rate may not be as good as the method above, but I've still had reasonable success taking this shortcut.
" I've also had success with layering - pull a bendy branch onto the ground next to the plant and pin it down with a piece of wire (bent to a tent peg shape) and cover at the peg with a little soil. Once it produces roots cut it off from the main stem and plant - it's an effective and easy way to grow a hedge.
If you are growing the plant commercially, plant in raised rows of well-drained soil in a north facing position for all day sun. The distance between rows will depend on whether you intend harvesting by machine or taking a more labour intensive hand harvesting approach.
Rosemary requires little ongoing maintenance. Plants like a pH balance of 6.5 to 7.0 which can be achieved with lime or by putting crushed shells around the base of plants every couple of years. Plants will tolerate dry conditions and mulching the plants is not recommended as it can cause fungal disease on the stems.
Rosemary Oil can be extracted using either steam distillation or hydro (water) distillation. Hydro distillation is where the herb is immersed in water and boiled, rather than passing hot steam through it. Hydro distillation produces a superior oil that isn't as chemically degraded as with hot steam distillation. It's easy to tell steam-distilled oil from hydro distilled. Oil smelling more like eucalyptus is probably steam distilled. Quality hydro distilled oil should smell almost like fresh Rosemary. It is hard to find information on yields - weight of plant harvested to essential oil produced - I believe yields are somewhere between 2 to 3% - i.e. approximately 25kg of leaf will produce 0.5kg of oil. Compared to lavender you will need more leaf to produce a given volume of oil, but you will end up with more hydrosol - a useful by-product of distillation.
Rosemary has to be one of the easiest herbs to use in cooking and there are so many delicious ways to use it in the kitchen. It's a perfect compliment for lamb and chicken dishes and aids the digestion of fat in the meat. Small branches with all the leaves stripped off make great skewers for lamb kebabs on the barbeque. Throw a few of the needles into the pan when you're frying a steak, or lay a few under a roast lamb with a bit of garlic. Rosemary adds great flavour to roasted potatoes - chop a little and sprinkle over the spuds with a little salt (use rosemary sparingly - it has a very strong distinctive flavour that can overpower).