Plant Allies: Focus on St. John's Wort

May 31, 2026

St. John’s Wort: The Midsummer Herb Hiding in Plain Sight

When you grow your own herb garden you are kind of signing up for something wild.

With herbs, if you let them go to seed you’ll find that the next year they are growing somewhere in your garden or yard in a completely unexpected place. That’s the case with my St. John’s wort. It started out in the Nettlesome herb garden, well contained in a pot. Then the next year I found it on the opposite side of the garden in a new pot. This year I found it growing out of the bricks in my garden wall and even in the gap between the concrete pavers of my backyard patio.

Where there is soil, St. John’s wort will grow.

St. John’s wort (Hypericum perforatum) is one of my favorite plants to work with. Most people know it as “that depression supplement” and leave it at that. But there is so much more to this plant; a long history, a fascinating chemistry, and a practical usefulness in both the medicine cabinet and the first aid kit that makes it worth really knowing.

Design by Kathryn

Getting to Know St. John’s Wort as a Plant

Before we talk about what it does, let’s sit with it for a minute. If you’re new to herbalism, I want to encourage you to resist the urge to skip straight to uses and dosages. A plant is not a pill. Getting to know how it grows, where it lives, what it looks and smells and feels like, that is part of the medicine.

St. John’s wort grows one to three feet tall with oval, opposite leaves that look completely ordinary at first glance. Hold a leaf up to the light though and you’ll see tiny translucent dots scattered across the surface — not actual holes, but clear oil glands. That’s where the species name perforatum comes from. Those little windows are one of your best identification clues.

The flowers are bright yellow, five-petaled, with a burst of stamens that give them an almost sparkly look in full sun. Look closely at the petal margins and you’ll see dark reddish-purple dots. Those dots contain hypericin, the compound responsible for the famous red oil and much of the plant’s medicinal action. The flower buds are equally important and are actually what I prioritize when harvesting.

The easiest identification test I know: squeeze a flower bud between your fingers. If it bleeds purple-red onto your skin, you have the right plant. If nothing happens, keep looking.

Here in Northern Utah, I find St. John’s wort growing along roadsides, at the edges of fields and trails, and anywhere the ground has been disturbed and the sun can get in. It thrives in poor, rocky soil. It does not need help to grow well. In many states and here in Utah it is actually considered invasive in agricultural land, which means you can often harvest it freely and abundantly without any concern about diminishing wild populations.

Herbal Characteristic

Botanical name: Hypericum perforatum
Family: Hypericaceae
Actions: anti-inflammatory, antiviral, nervine, vulnerary, astringent, nervous system trophorestorative.
Energetics: cooling, drying
Taste: sweet oily, pungent
Parts used: flowering tops and buds (fresh is a must)

What St. John’s Wort Actually Does

St. John’s wort has a particular affinity for the nervous system. Whether you’re using it topically or internally, it keeps coming back to nerves. Externally, it shines for any pain that follows the path of a nerve: sciatica, neuralgia, nerve pain from injury, post-herpetic pain after shingles. I reach for the oil anytime a client describes pain that radiates or shoots rather than sits in one place.

It is also a beautiful wound herb. The infused oil has anti-inflammatory and vulnerary properties that make it useful for bruises, sprains, muscle soreness, burns, and general skin repair. I have seen it do impressive things on burns in particular.

Internally, the tincture is what most people associate with mood support — and that reputation is earned. It has been studied more thoroughly than most herbs for its effects on mild to moderate depression and seasonal affective disorder. It is not a quick fix and it is not the right tool for severe depression. But for the low, gray, tired kind of sadness that settles in especially in the shorter months, it is worth knowing.

It has also been used historically as an antiviral, particularly for viruses that have an affinity for the nervous system. This is a less well-known use but one that shows up consistently in the older literature. It has been found to be very useful with the herpes simplex 1 and 2 and in was used to help treat AIDS patients in the early days of the outbreak.

Oil or Tincture: Which One Do You Need?

The infused oil is for external use. You put it on your body. It is what I make and keep in my herbal first aid kit, and it is what I reach for with burns, bruises, sore muscles, nerve pain, and skin repair. You can use it straight or make it into a salve with beeswax. It does not go in your mouth.

The tincture is for internal use. It is an alcohol extraction of fresh flowers and buds, and it is how you access the plant’s systemic effects — mood, nervous system, antiviral action. The alcohol pulls out both the fat-soluble hypericin and the water-soluble compounds like hyperforin and the flavonoids. You get a more complete picture of the plant than either oil or water alone would give you.

One important thing to know about the tincture: St. John’s wort is a strong inducer of a liver enzyme called CYP3A4, which is responsible for breaking down a long list of pharmaceutical medications. This means it can significantly reduce the effectiveness of birth control, antidepressants, antivirals, blood thinners, and immunosuppressants, among others. This is not a reason to avoid the plant. It is a reason to do your homework first and talk to your physician or herbalist if you are on any of those medications.

Many people use both: the oil topically for physical pain and injury, the tincture internally for nervous system and mood support. They work well together and there is no reason you can’t have both in your kit.

A note about the oil and sun: St. John’s wort oil is photosensitizing. Hypericin increases your skin’s sensitivity to UV radiation. Apply it only to skin that will be covered or out of direct sun. This is especially worth knowing in the summer when you’re harvesting and making the oil and might be tempted to use it right away on sun-exposed skin.

Some herbalist also dry the flowers and buds and use them in teas though herbalist Michael Moore says the dried flowers in tea are much less effective.

Why the Oil Turns Red

This is one of the things I love most about working with this plant. You fill a jar with bright yellow flowers, cover them with oil, set it in a warm spot, and over the course of a few weeks something almost unbelievable happens. The oil slowly turns red. Not orange. Not pink. A deep, saturated, jewel-toned red that looks like it should not be coming from a plant you found on the side of the road.

The color comes from hypericin and pseudohypericin, deeply pigmented compounds that are fat-soluble and transfer readily into oil. They are the same compounds responsible for that purple-red stain on your fingers when you pinch a bud. The depth of the red color in a finished oil is generally a good indicator of quality. It tells you the flowers were harvested at peak, the plant was correctly identified, and the infusion had enough time to do its work.

A pale yellow or orange oil usually means the flowers were past their prime, or the plant was harvested too early, or the infusion time was too short. You want red. Go for red.

One thing I’ll say clearly here: use fresh flowers. Not dried. The hypericin content is highest in fresh plant material and dried flowers make a noticeably weaker oil. I wilt mine for about 12 to 24 hours before infusing to reduce the moisture content — too much water in the jar can lead to mold, and a ruined oil is genuinely heartbreaking after six weeks of waiting, but I do not dry them fully.

A Very Old Plant with a Very Long History

The name tells you a lot. St. John’s wort blooms at its peak around June 24th, the Feast of St. John the Baptist in the old Christian calendar or Midsummer’s Day. Wort is simply an Old English word for plant or herb. So the name is essentially just: John’s plant, the midsummer one.

In pre-Christian and early Christian Europe, the days around the summer solstice were considered a charged and liminal time; full of power, and not a little danger. St. John’s wort was believed to be protective. People hung bundles of it over doorways to ward off lightning and evil spirits. They slept with it under their pillows. They threw it onto midsummer bonfires. The red oil it produced was understood as something close to sacred — some called it the blood of St. John — and was used on wounds, burns, and what older texts called melancholy.

Dioscorides wrote about it in the first century. It appears in medieval European herbals and monastic medicine texts. In Germany it is still called Johanniskraut. In the British Isles it was known as chase-devil. The doctrine of signatures (the old idea that a plant’s appearance hints at its use) had a field day with this one: the perforated leaves letting in light, the red staining juice, the way it opens fully at the longest day and seems to gather all that summer sun into itself.

It wasn’t until the 1990s that the plant attracted serious clinical research in Europe and the U.S. But the folk knowledge was already two thousand years deep by then. That’s usually how it goes.

When to Plant St. John’s Wort

If you want to grow your own, and I recommend it, St. John’s wort is one of the easier perennial herbs to establish. It wants full sun and well-drained soil. It actually does better in poor, rocky, or sandy conditions than in rich garden soil. It is drought-tolerant once established, deer-resistant, and perennial in zones 3 through 9. Though I can grow in the wet riparian areas of the intermountain west. It's quiet resilient.

From seed, direct sow outdoors in early spring once frost risk has passed. The seeds need light to germinate, so press them into the surface of the soil and don’t cover them. Cold stratification (six to eight weeks in a moist medium in the refrigerator) significantly improves germination rates. You can also start seeds indoors six to eight weeks before your last frost date.

If you can get a transplant or a division from someone who already has it growing, that’s the easier route. Transplants establish faster and will often flower in their first or second season.

* Be aware that St. John’s wort spreads. It self-seeds readily and spreads by rhizome. I’ve found this to be a feature rather than a problem when you’re growing it for medicine, but if space is limited you may want to give it a contained bed or stay on top of it after it flowers.

When to Harvest St. John’s Wort

Timing matters more with this plant than almost any other I work with. The harvest window is short (maybe two to three weeks) and it falls right around the solstice. Which is, of course, exactly why the old midsummer traditions grew up around it.

You want to harvest when the plant is at peak bloom: open flowers and plump, unopened buds present at the same time. The buds are as important as the flowers, maybe more so. They are dense with hypericin and will continue releasing into your oil as the infusion progresses.

Do the squeeze test. Pinch a bud. If your fingers go deep reddish-purple, harvest now. If the stain is pale orange or barely there, give it a few more days and check again.

In most of Northern Utah and the Intermountain West, peak bloom falls somewhere between mid-June and mid-July. I try to check on my plants every day or two once I see the first flowers opening. I’ve missed the window before by waiting too long. Once the flowers go to seed you don't want to harvest them for medicine any more. Though I have found that the more you harvest the more the plant flowers, much like calendula.

Harvest on a dry morning after the dew has lifted. Collect the top two to three inches of the flowering stems: flowers, buds, a few leaves. Don’t bother with stems that are mostly seed pods already.

For oil: wilt your harvest for 12 to 24 hours before infusing to reduce water content, then stuff a mason jar 3/4 full with the flowers and buds (a few leaves are ok too). Fill it with oil , making sure the material is covered completely.

For tincture: use fresh flowers immediately in high-proof alcohol, at least 60%. The fresh plant gives you the most complete extraction of both the fat-soluble and water-soluble constituents.

Once you find St. John’s wort once, you find it everywhere. It has a way of suddenly appearing on trails you’ve walked a hundred times, along fence lines you’ve driven past for years. It has always been there. It grows in the marginal places, the edges, the thresholds, the disturbed ground. Midsummer’s plant, blooming at the hinge of the year, available to anyone who knows what they’re looking at.

Find it, grow it, make some oil.

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