Rosemary

 

Rosemary loves full sun and good drainage.

Rosemary is one of the most familiar and recognizable culinary herbs, grown in many home gardens as a tasty compliment to chicken, pork, eggs, and many other dishes.  Rosemary looks like a tiny pine sapling, and in many ways this resinous evergreen is reminiscent of the full-sized trees; for this reason, it makes a very easy-to-care-for herbal bonsai.  This herb, however, can also grow to a height of four feet!  In warm climates, it lends itself to topiary designs and can be quite a large shrub.  Here in Virginia, however, it typically stays in a compact, low-growing shape that rarely reaches three feet tall.

The scent of rosemary wafts up whenever this soft, woody herb is brushed or disturbed, and the dried leaves of rosemary can be added to sachets for a clean, refreshing aroma.  The flowers, which bloom along the stems throughout the warm months, are small and discreet, but charmingly pretty: a soft purple blossom that pollinators adore.  Its resinous, evergreen odor helps protect certain garden plants (such as aliums like onions and chives) from insects (such as black onion aphids), possibly by disguising the aroma of the onions which would attract the pests to the plants in the first place, or possibly by driving away those pests altogether.

Young rosemary has a vivid lime tone to its vigorous growth; this color mellows down to a blue-grey foliage as the plant matures.

One of the most important aspects of rosemary is its antimicrobial and antioxidant activity.  This trait has been extensively studied since the 1970's, making rosemary one of the most widely-used food sanitation ingredients in the world, especially in commercial food preservation.  Rosemary, dried and chopped, has antioxidant effects that help prevent degradation of lipids (fats) and proteins, preserving food nutrient quality and coloration.  Rosemary extract and rosemary essential oils are used to stabilize cooking oils, especially fryer oils, helping prevent the oil from going rancid.

Amazingly, rosemary is effective against E. coli, L. monocytogenes and S. aureus, all of which are very resistant and dangerous bacteria.  For this reason, chopped rosemary, dried rosemary, and rosemary extract are all commonly added to prepared foods where E. coli, listeria and staph could be a concern (especially ground meats and chopped vegetables).  Similarly, rosemary oils or extracts are frequently added to food-safe cleaning sprays and detergents. See "Antioxidant and Antimicrobial Properties of Rosemary (Rosmarinus officinalis, L.): A Review" (2018): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6165352/

Rosemary has also been proven effective in-vitro against even that most difficult of infectious bacteria, MRSA (methicillin-resistant Staphylococcus aureus). Against some strains of MRSA, a simple, crude ethanolic extract of rosemary has proven as a true antibiotic; for other, more challenging strains, rosemary is at least bacteriostatic (growth inhibiting) and capable of preventing the bacteria from forming micro-films. See "In vitro antibacterial activity of medicinal plants against biofilm-forming methicillin-resistant Staphylococcus aureus: efficacy of Moringa stenopetala and Rosmarinus officinalis extracts" (2019):  https://www.sciencedirect.com/science/article/pii/S2405844020301481

Rosemary extracts are considered very safe for consumption, even up to such high levels of intake as 400 mg/kg of food or beverage, according to the European Food Safety Authority.  Rosemary is even added to livestock feed or administered as a supplement, in order to improve lipid and protein stability in meat and egg products.

These more commercial and medical uses of rosemary can easily benefit the gardener in the private kitchen.  Adding chopped rosemary to ground meat and sausage during home butchering, for example, will help sanitize and preserve the meat (in addition to regular curing, freezing, dehydration or canning methods; rosemary is not meant to be used alone, but as complement to sanitary cooking procedures).  Making ethanol extracts (like a tincture, but using a 1:1 ratio of chopped, dried rosemary to alcohol, by weight, and letting it soak for at least 24 hours before filtering the solids, and then dehydrating to remove the alcohol) is relatively easy to accomplish at home without specialized equipment.  These extracts can be used as medicine or added to foods for a more concentrated and powerful effect against microbes.  Tinctures and infused oils, of course, are very popular home uses for rosemary.  Cold-pressed oils can be more challenging to make at home, but can yield potent cleansers for home applications, not to mention fragrant additions to soaps and perfumes.

Rosemary plants in the garden (like the one hiding in the center of this photo) can help protect aliums, like these Egyptian Walking Onions, from black onion aphids.  This is thanks to the pungent aroma of evergreen rosemary, which overwhelms even the scent of onion plants.

As a medicinal herb, rosemary is more famous for its traditional memory-enhancement uses.  Modern science has begun to validate this use, as well.  At dosages as low as 150 mg/kg, rodent studies demonstrated that rosemary extract improves both learning and memory, both short and long term; see "The effects of acute administration of the hydroalcoholic extract of rosemary (Rosmarinus officinalis L.) in animal models of memory," (2012): https://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-82502012000300005  Other studies have shown that oral administration of rosemary extract helps healthy adult humans (under 63 years old) build and retain verbal memories, when compared with placebo treatment in randomized, double-blind trials.  Recently, scientists have begun exploring the anti-inflammatory and neuroprotective properties of rosemary against brain damage and the side effects of various psychoactive medications, finding positive initial results that should encourage further studies on this topic.

Likewise, traditional European medicine recommends rosemary as an anti-depressant, mood-improving medicine (often administered as a simple herbal tea/tisane of the leaves and/or flowers).  Rodent and canine models have shown that rosemary affects the dopamine system and does, indeed, possess some anti-depressant activities, although the efficacy in humans has yet to be carefully studied.  Furthermore, a placebo-controlled study in 2009 demonstrated that even the scent of rosemary (compared to that of other massage oils) stimulated significant increases in breathing rate, systolic blood pressure, and diastolic blood pressure, which indicate an increase of autonomic arousal.  See "Simultaneous Aromatherapy Massage with Rosemary Oil on Humans," (2009): https://www.mdpi.com/2218-0532/77/2/375

As a cognition booster and anti-inflammatory herb, a mood booster and stimulating aromatic, rosemary deserves a place in the shelves of every herbalist and homesteader.  Medicinally, its antibacterial, antifungal, anticancer, antioxidant and hypoglycemic properties make it an important tool for independent resilience.  As a pest-preventative garden perennial, rosemary likewise should take a spot of honor in the sunshine in every apothecary garden and potager--or, for climates that are too cold for rosemary, the herb should overwinter indoors in a sunny window.  This forgiving, elegant and easy-to-grow herb also makes a charming herbal bonsai!

We sell young Arp rosemary plants (the most winter-hardy cultivar of rosemary, capable of surviving winters here in USDA zone 7) and rosemary bonsai plants.  Email to inquire about current availability!

Safety Note

Be cautious when using any medicinal plants.  All plants are subject to variability in cultivar, age, growing location, soil, climate, stress, fertilization, etc.  Thus, dosage with any herb or medicinal plant is never precise, as it is with isolated chemicals, and caution is required with any supplementation or therapeutic use of plant-derived medicines.  Please consult with a trained professional if relying upon herbal remedies, and always remember to inform your primary care physician if you use plant-based supplements or medicines.  There can be interactions with prescribed medications, as well as allergic reactions.  When first using any medicinal plant, start small and observe caution; be alert for signs of negative reaction and discontinue if side effects arise, until you can discuss your concerns with a trained herbalist.  Natural remedies are still chemicals!  Use common sense and be safe.