You can make rosemary oil at home by steeping rosemary in a carrier oil, either slowly over several weeks or with gentle heat in under an hour. This infusion method produces a fragrant oil suitable for cooking, skincare, or hair care. True rosemary essential oil requires steam distillation equipment and yields very little product, so most home producers stick with infused oil, which captures many of the same beneficial compounds.
Infused Oil vs. Essential Oil
These are two fundamentally different products. An infused rosemary oil is made by soaking rosemary in a base oil like olive or jojoba, which draws out the plant’s flavor and aromatic compounds over time. The result is a mild, versatile oil you can cook with, massage into your scalp, or use in homemade skincare.
Essential oil, by contrast, is produced through steam distillation. It’s a concentrated extract containing volatile compounds like 1,8-cineole (27 to 53% of the oil), alpha-pinene (8 to 20%), and camphor (around 8.6%). The yield is tiny: steam-distilling 2.5 kilograms of fresh rosemary leaves and twigs with 7 liters of water for about two hours produces an oil yield of roughly 0.45 to 0.59% by volume. That means you’d need enormous quantities of plant material for even a small bottle. Unless you own a home still, infusion is the practical route.
Cold Infusion Method
Cold infusion is the simplest approach and requires no special equipment. It takes 2 to 6 weeks but preserves heat-sensitive compounds in both the rosemary and the carrier oil.
- Dry your rosemary. Spread sprigs on a baking sheet or hang them in a warm, dry area until the leaves are completely dry and crumble easily. Using dried rosemary is critical for safety (more on that below).
- Fill a clean glass jar. Pack it about one-third to one-half full with dried rosemary leaves. You can strip the leaves from the stems or leave small sprigs intact.
- Pour in your carrier oil. Olive oil works well for culinary use. Jojoba, sweet almond, or grapeseed oil are better choices for skin and hair applications. Cover the rosemary completely, leaving about an inch of oil above the plant material.
- Seal and store. Place the jar in a sunny windowsill or a consistently warm spot. Shake it gently every day or two to redistribute the herbs.
- Strain after 2 to 6 weeks. Pour the oil through cheesecloth or a fine mesh strainer into a clean, dry bottle. Squeeze the cheesecloth to get every last drop. Discard the spent rosemary.
Longer infusion times produce a more potent oil. Two weeks gives a light fragrance suitable for cooking. Four to six weeks creates a stronger product better suited for topical use.
Warm Infusion Method
If you need rosemary oil the same day, gentle heat speeds up extraction dramatically. The process takes 30 minutes to a few hours instead of weeks.
Set up a double boiler by placing a heat-safe glass jar or smaller pot inside a larger pot filled partway with water. Add your dried rosemary and carrier oil to the inner container. Heat the water on low, keeping the oil temperature below 43°C (110°F). At this range, the warmth coaxes out the rosemary’s compounds without degrading the oil. A kitchen thermometer is helpful here.
Maintain this gentle heat for 1 to 3 hours, checking occasionally that the water hasn’t evaporated. A slow cooker on its lowest setting works well as an alternative, since it holds a steady, low temperature with less babysitting. After heating, let the oil cool completely, then strain through cheesecloth into a clean bottle.
The warm method produces a slightly different flavor and aroma profile compared to cold infusion. The heat tends to pull out more of the earthy, resinous notes, while cold infusion can retain brighter, greener qualities.
Choosing a Carrier Oil
Your carrier oil determines how long the finished product lasts and what you can use it for. Olive oil is the classic choice for kitchen use and has a long shelf life of 1 to 2 years unopened. For body and hair applications, jojoba oil is popular because it closely mimics the skin’s natural oils and resists going rancid. Sweet almond oil absorbs quickly into skin, making it a good option for massage blends. Grapeseed oil is lightweight and nearly odorless, so it lets the rosemary scent come through clearly.
Avoid oils that spoil quickly, like flaxseed or hemp seed oil, unless you plan to use the finished product within a few weeks and keep it refrigerated.
Botulism Risk and Food Safety
This is the one area where homemade herb oils carry genuine risk. Fresh herbs contain moisture, and when submerged in oil (an oxygen-free environment), they can create ideal conditions for the bacteria that cause botulism. A 1999 outbreak in Florida was traced directly to homemade garlic-infused oil that also contained rosemary and thyme.
The safest approach is to always use thoroughly dried rosemary. Dried herbs have had their moisture removed, which significantly reduces the risk. Food safety guidelines from university extension services recommend refrigerating herb-infused oils and using them within 10 days if you want to be cautious. Some sources extend that to 3 weeks under refrigeration. If you use dried rosemary exclusively and store the oil in the refrigerator, the risk drops substantially. Never store fresh-herb-infused oils at room temperature.
Storage and Shelf Life
Store your finished rosemary oil in a dark glass bottle (amber or cobalt blue) to protect it from light, which accelerates rancidity. Keep it in a cool, dark place or in the refrigerator. A properly made infusion with dried herbs and a stable carrier oil like olive or jojoba will keep for several months at room temperature and longer in the fridge.
You’ll know the oil has gone off if it smells sour, musty, or noticeably different from when you made it. When in doubt, make smaller batches more frequently rather than one large batch that sits for months.
Using Rosemary Oil for Hair Growth
One of the most popular reasons people make rosemary oil at home is for hair care. A 2015 clinical trial compared rosemary oil to 2% minoxidil (the active ingredient in Rogaine) in 100 people with androgenetic alopecia. After six months, both groups showed a significant increase in hair count, with no meaningful difference between them. Notably, neither group saw results at the three-month mark, so patience matters.
For scalp use, you can apply your homemade infused oil directly, massaging a small amount into your scalp and leaving it on for at least 30 minutes before washing. If you’re using a purchased rosemary essential oil instead, it needs dilution in a carrier oil first. General guidelines suggest keeping essential oil concentrations at 0.5 to 1.2% for facial and sensitive skin areas, which translates to roughly 3 to 7 drops of essential oil per tablespoon of carrier oil.
Tips for a Stronger Infusion
If your first batch comes out too mild, there are a few adjustments to try. You can do a “double infusion” by straining out the first batch of spent rosemary and pouring the already-infused oil over a fresh batch of dried herbs for another round. This concentrates the flavor and aroma without adding heat. You can also increase the ratio of rosemary to oil, packing the jar closer to half full rather than one-third. Crushing or lightly bruising the dried leaves before adding them to the oil exposes more surface area and speeds extraction. Finally, extending a cold infusion to the full six weeks rather than pulling it early makes a noticeable difference in potency.