You can make hyssop oil at home by infusing dried hyssop in a carrier oil, a straightforward process that requires no special equipment. True hyssop essential oil, on the other hand, requires steam distillation and yields very small amounts, typically 0.4% to 0.93% of the plant material by weight. Most home herbalists get better results with the infused oil method, which captures many of the plant’s aromatic and therapeutic compounds in a usable form.
Harvesting Hyssop at the Right Time
The oil concentration in hyssop peaks during full bloom, so timing your harvest matters. Plants harvested at full flowering produce roughly twice the essential oil content of those cut before blooming. If you’re growing your own, wait until the majority of flower spikes are open rather than picking early.
Time of day also plays a role. Studies on hyssop have found the highest essential oil concentration in evening harvests for both fresh and dried herb. Cut the flowering aerial parts (stems, leaves, and flowers) in the late afternoon or early evening for the strongest aromatic profile. Hyssop plants are perennial and can remain productive for about 10 years, so you’ll get repeated harvests from the same planting.
Drying the Herb
Drying hyssop before infusing it removes moisture that could introduce mold or bacteria into your oil. Tie small bundles of stems together and hang them upside down in a warm, dry, well-ventilated area out of direct sunlight. This typically takes 5 to 10 days depending on humidity. The herb is ready when the leaves crumble easily between your fingers and the stems snap rather than bend.
You can also use a dehydrator set to around 95 to 105°F (35 to 40°C), which speeds the process to roughly 24 to 48 hours while preserving volatile compounds. Avoid using an oven, which tends to run too hot and drives off the aromatic oils you’re trying to capture.
Making Hyssop-Infused Oil
An infused oil is the most practical way to make hyssop oil without specialized equipment. You’re essentially dissolving the plant’s fat-soluble compounds into a carrier oil over time. Here’s how to do it:
- Choose a carrier oil. Jojoba, sweet almond, and coconut oil all work well. Jojoba has the longest shelf life because it’s technically a liquid wax and resists going rancid. Olive oil is another common choice, though it has a stronger scent that can compete with the hyssop.
- Fill a clean, dry glass jar. Pack it about two-thirds full with dried hyssop. Don’t use fresh herb, as the water content promotes spoilage.
- Pour carrier oil over the herb. Cover the plant material completely, leaving about an inch of oil above the top of the herb. Any exposed plant material will mold.
- Seal and infuse. Close the jar tightly and place it in a warm, sunny windowsill. Let it sit for 4 to 6 weeks, shaking it gently every day or two to redistribute the plant material.
- Strain. Pour the oil through cheesecloth or a fine mesh strainer into a clean jar, squeezing out as much oil as possible from the spent herb. Discard the plant material.
The Quick Heat Method
If you don’t want to wait a month, you can speed up extraction with gentle heat. Place the jar of oil and herb in a slow cooker filled with a few inches of water, set it to the lowest setting, and let it warm for 4 to 8 hours. Alternatively, use a double boiler on the stovetop over very low heat for 2 to 3 hours. The oil should stay warm but never hot enough to simmer or smoke. Strain as described above. The cold infusion method generally produces a more complex aromatic profile, but the heat method works when you need the oil sooner.
Steam Distillation for Essential Oil
If you want a concentrated essential oil rather than an infused oil, you’ll need a still. Home distillation kits designed for essential oils are available and typically include a boiler, a column or retort for the plant material, a condenser, and a separator to collect the oil from the water.
The basic process involves generating steam in one chamber and passing it through the dried hyssop in another. The steam carries volatile aromatic compounds out of the plant material, then travels through a condenser where it cools back into liquid. The resulting liquid separates into two layers: a thin film of essential oil floating on top of aromatic water (hydrosol). You collect the oil with a pipette or a separating funnel.
Expect modest yields. Research on hyssop distillation consistently reports oil yields in the range of 0.4% to just under 1% of the dried plant material. That means 100 grams of dried hyssop produces roughly 0.4 to 1 gram of essential oil. Distillation runs typically last about 2 hours. Because the yield is so small, most people growing hyssop at home find the infused oil method far more practical.
Storage and Shelf Life
Store your finished hyssop oil in dark glass bottles (amber or cobalt blue) in a cool place away from light and heat. Light and warmth accelerate oxidation, which degrades the oil’s aroma and beneficial compounds over time. An infused hyssop oil made with jojoba will last up to 2 years; one made with sweet almond or olive oil is best used within 6 to 12 months. Essential oil, if you distill it, keeps longer, generally 2 to 3 years when stored properly. Label your bottles with the date so you can track freshness.
Safety Considerations
Hyssop essential oil contains compounds called pinocamphone and isopinocamphone, monoterpene ketones that can stimulate the nervous system. These compounds typically make up 30% to 50% of the essential oil, and in high concentrations they can trigger seizures. This makes hyssop essential oil one of the more potent oils in terms of neurological risk.
People with epilepsy or other seizure disorders should avoid hyssop essential oil entirely. It’s also not appropriate for pregnant women or young children. Even for healthy adults, hyssop essential oil should always be diluted in a carrier oil before applying to skin, and it should not be taken internally in concentrated form. Infused hyssop oil is considerably milder than distilled essential oil because the concentration of these ketones is much lower, but the same cautions apply to anyone in a high-risk group.
The FDA lists hyssop oil as Generally Recognized as Safe (GRAS) for use as a flavoring agent, which means the tiny amounts used in food products are considered safe. That designation doesn’t extend to therapeutic doses of the concentrated essential oil.