How to grow American Skullcap / Frossört

20 maj 2025

American skullcap is a nervine herb traditionally used to support the nervous system. It’s known for its relaxing properties and is often used to ease tension, promote restful sleep, and help the body recover from long-term stress. While it's subtle in action, it builds nerve strength over time.

Name: In Swedish: frossört, English: American skullcap

Latin name: Scutellaria lateriflora

Family: Lamiaceae (mint family)

Life cycle in Sweden: Perennial.

Hardiness: In Sweden, skullcap behaves as mint. In winter, the above-ground parts die back, and the plant survives only through underground stolons. These stolons store energy and push up new shoots in spring. In Zone 4 and colder, this survival strategy works well. It usually re-appearing in early May.

Appearance: Skullcap forms bushy, low-growing plants (around 30–60 cm tall) with toothed green leaves and small purple-blue flowers. Skullcap spreads through underground stolons, so it will gradually fill the space around it. Plants usually flower in July and can keep producing until early autumn.

How to Start Skullcap

You can grow skullcap from either seeds or cuttings. Skullcap is rare in Sweden and is not commercialized by plant nurseries (plantskola). However, at Nordiska Örter, I offer cuttings every spring for those who wish to grow it in their gardens.
If purchasing from elsewhere, be sure the seeds are fresh (from the current or previous season) and sourced from a reputable supplier specializing in medicinal plants. Many commercial varieties focus on ornamental traits, which may differ in aroma and potency from those grown for herbal use. To obtain seeds, you can puchase cuttings and at the end of the growing season collect the seeds for the following season.

Growing from seeds

Skullcap seeds do not need cold stratification. You can sow them indoors in March. To sow I use sowings module trays where I place 3 to 4 seeds per module. Do not cover seeds with soil as the seeds need light to germinate. Germination usually takes 1–2 weeks at room temperature. After what, when seeds pop up, I transplant young plants once they have at least two sets of true leaves and separate them into individual pots to grow each seedlings in a pot. Leave then grow until planting in the garden.

For robust, well formed and well develop seedlings, I fertlise a week after transplantation by watering plants with golden water or liquid organic fertiliser.

Growing from cuttings

Growing skullcap from cuttings is much easier. In May, look for young, bright green shoots just emerging from the ground. These are perfect for taking vegetative cuttings. Simply cut a rooted healthy shoot, plant it directly into moist soil, and water well every day for the first couple of weeks. The cuttings root easily and grow into strong plants.

Outdoor planting

From mid-May plants can be transplanted outdoors. Skullcap prefers evenly moist conditions. It will tolerate dry periods once established, but it thrives when the soil doesn’t completely dry out.

Soil and Sun Requirements

Skullcap loves conditions similar to where it grows in the wild:

Soil: Moist, fertile, and well-drained

Light: Full sun to partial shade. Morning sun and afternoon shade is ideal, planting it where a tree gives shade later in the day helps keep the soil and air cooler and more humid, which skullcap loves.

Planting Layout

Place plants about 20 cm apart in a row, and leave 30 cm between rows. That said, skullcap spreads like mint, so spacing doesn’t need to be perfect, it will fill in on its own the following years.

Seedlings are delicate during their first season. Their stems break easily, so don’t be surprised if you see fallen stems near your young plants. After their first winter, they become much stronger and more resilient.

Harvest Specifications

Parts used: Aerial parts—leaves, stems, and flowers

When to harvest: Harvest skullcap when it is in full bloom—this is when the plant is at its most potent, usualy at the start of flowering, usually July to early August.

How to harvest: Cut the upper portion of the plant about 15cm aboveground. Cutting 15cm aboveground helps the plant recover and can even give you the chance for a second harvest later in the season if conditions allow. Whether you're harvesting whole stems or just the tops, make a clean cut with a well-sharpened blade. This helps the plant recover quickly and reduces the risk of disease.

Skullcap is shallow-roote during the first year of growth or under dried conditions, it can be easily pulled out of the soil by accident. So be extra gentle when harvesting.

Drying and storage

Dry the skullcap in a warm, well-ventilated, and shaded space to preserve its color and potency or in a electric dryer. Spread the plants out in a thin layer, ideally on a screen or drying rack. Drying is complete when both the leaves and stems easily crumble when crushed between your fingers.

Drying temperature: 35°C

Drying time: Usually 1–3 days

Conditions: Dry quickly in a dark, airy space to preserve the green color and potency.

💡 Drying tips: For non-aromatic plants like skullcap, drying herbs on racks in a sauna works very well. The warm, dry air speeds up the process, and the plants are protected from sunlight, which helps keep their color and strength. Just make sure to open the sauna regularly to let the moisture escape and keep temperature not exceeding 50 degrees. In most cases, your herbs will be fully dry within 24 hours.

While many sources distinguish between passive drying (air drying in bunches) and active drying (using a dehydrator or controlled environment), I personally think active drying is almost always best when possible. With active drying, you can control both temperature and ventilation, which gives a more consistent result and helps preserve color, aroma, and potency. I might write a full post on this soon!

How to prepare skullcap

Skullcap is best tinctured fresh. It has a high water content, so it’s ideal to use a strong alcohol, around 50–60%. This ensures proper extraction and helps preserve the tincture.

However, if your skullcap was grown in dry soil, the water content may be lower, and a standard 30–40% alcohol can work just fine. Always consider the plant’s moisture level when deciding on alcohol strength.

Another solution to not use high pourcentage of alcohol is to let the fresh herb wilt for about 12 hours to reduce surface moisture. Then chop it up and macerate in alcohol or place the herbs and alcohol in a blender and leave it macerate for two weeks.

Infusion (herbal tea): Use dried leaves and flowers for a calming evening brew. Skullcap in rarely consumed alone but present in tea blends.