Spend twenty minutes in any health food store and you’ll find bottles making claims that the clinical literature doesn’t support. The gap between what an herb is marketed for and what human trials have actually tested is significant for most medicinal plants. That doesn’t mean these herbs are worthless - some have genuine evidence, and nearly all of them are cheap and easy to grow. But the evidence varies a lot by herb, and it’s worth knowing what grade you’re working with before you decide what to plant.
This breakdown covers seven common medicinal and tea herbs: what the clinical evidence actually says, what the National Center for Complementary and Integrative Health (NCCIH, nccih.nih.gov) rates each one, and what the economics look like for a home grower. The economics case comes first, because for many of these herbs the primary value is practical rather than medicinal - a pound of home-dried chamomile makes a lot of tea regardless of what you think about its anxiolytic properties.
The Economics Before the Herb-by-Herb Breakdown
Dried medicinal herbs are not cheap at retail. Frontier Co-op and Mountain Rose Herbs - two of the more reputable bulk herb suppliers - price quality dried herbs in the following ranges:
| Herb | Retail price/lb (bulk dried) |
|---|---|
| Chamomile flowers | $12-25 |
| Lemon balm leaf | $10-20 |
| Peppermint leaf | $8-18 |
| Lavender flowers | $15-35 |
| Echinacea leaf/flower | $15-28 |
| Valerian root | $12-22 |
| Ashwagandha root | $15-30 |
Prices from Frontier Co-op and Mountain Rose Herbs current retail listings, April 2026.
A standard herbal tea uses roughly 2g of dried herb per cup. One pound of dried herb is 454g, so: 454 ÷ 2 = 227 cups per pound. At $15/lb retail for chamomile, you’re paying about $0.07 per cup of loose-leaf tea. Commercial chamomile tea bags run $0.15-0.40 per bag - often with less herb per bag than a proper loose-leaf dose.
Home-grown changes that math entirely. German chamomile (Matricaria chamomilla) starts from seed for roughly $2-4 per packet, produces 0.5-1.0 lb of dried flower heads per season from an established planting, and self-seeds aggressively after the first year. The seed cost amortizes to near zero. Your chamomile tea costs the water and the five minutes it takes to harvest.
The savings aren’t dramatic for someone who drinks one cup of chamomile tea per week. For a daily tea drinker going through 2-3 lb of dried herb per year, growing your own represents $30-75 in annual savings for chamomile alone - and more for lavender, which can run $35/lb at specialty retailers.
What a small bed yields
A 4x8 foot bed with 4-6 plants of an established perennial herb - peppermint, lemon balm, lavender - will yield 1-2 lb of dried herb per species per season once established. In the first season, expect 0.5-1 lb from perennials that are still putting energy into root development. Annuals like German chamomile can hit 0.5-1 lb dried in their first season if direct-seeded early and harvested consistently.
These aren’t theoretical numbers. They’re the figures used by the American Herb Society and land-grant extension programs for planning purposes. Your actual yield depends on soil quality, harvest timing, and how aggressively you harvest before plants bolt.
Chamomile (Matricaria chamomilla, German; Chamaemelum nobile, Roman)
Evidence grade: Clinical trial support exists for anxiety reduction; NCCIH rates evidence as “some evidence suggests benefit” for anxiety.
Chamomile is the best-evidenced herb on this list for a specific claim. Amsterdam et al. (2009), published in the Journal of Clinical Psychopharmacology, ran an 8-week randomized controlled trial comparing chamomile extract to placebo in adults with mild to moderate generalized anxiety disorder (GAD). The chamomile group showed statistically significant reductions in GAD symptom scores compared to placebo. That’s a real clinical trial with a specific outcome measure - not in vitro data or traditional use documentation.
NCCIH notes anti-inflammatory properties are also documented, with the mechanism attributed to the flavonoid apigenin binding to benzodiazepine receptors. The sleep-promoting claim is less well-supported than the anxiety claim; the same NCCIH review notes insufficient high-quality evidence for sleep specifically.
What the evidence doesn’t support: treating any medical condition, replacing anxiety medication, or specific dosing for therapeutic effect. The Amsterdam trial used a standardized extract at 220mg-1100mg per day - not a cup of tea with 2g of dried flowers. Tea is likely lower potency than concentrated extracts used in trials.
Growing: German chamomile is an annual. Direct-sow in early spring or fall; it tolerates frost and germinates readily in cool soil. The plants grow 12-24 inches tall and produce small daisy-like flowers with yellow disc centers and white ray petals. Harvest at peak bloom - when the disc florets are fully open and beginning to flatten outward - for the highest volatile oil and flavonoid content. Roman chamomile (Chamaemelum nobile) is a low-growing perennial in zones 4-9; it produces flowers with a somewhat stronger, more apple-like scent but is less productive than German.
German chamomile self-seeds prolifically. After the first season, you’ll have more plants than you know what to do with unless you deadhead before seed set. Most growers consider this a feature.
Yield and value: 0.5-1.0 lb dried flower heads per season from an established planting. Retail: $12-22/lb. Internal link: chamomile crop page.
Lemon Balm (Melissa officinalis)
Evidence grade: Traditional use well-documented; clinical evidence is limited; NCCIH rates as insufficient evidence for most claims.
Lemon balm has a long history of use in European herbal medicine for anxiety and sleep, documented in sources going back to the 16th century. Clinical evidence is another matter. Small trials have suggested mild sedative effects, but most are underpowered, short-duration, and lack placebo controls rigorous enough to distinguish herb effect from expectation effect.
In vitro evidence for antiviral activity - specifically against Herpes simplex - exists. A study by Koytchev et al. (1999) in Phytomedicine tested a topical lemon balm cream on labial herpes lesions and found reduced healing time. But in vitro and topical cream results don’t translate to “drinking lemon balm tea treats cold sores.” NCCIH’s current summary: insufficient evidence to draw conclusions about lemon balm for most uses.
That said, it makes an excellent tea. The fresh-crushed leaf smells strongly of lemon, the tea is pleasant, and if the anxiolytic effect is real at tea doses - even partially - it’s a low-risk addition to an evening routine.
Growing: Perennial in zones 4-9. Lemon balm is a member of the mint family and spreads aggressively by seed and rhizome - plant it where you can manage the spread, or give it its own contained bed. Harvest before flowering; volatile oil content peaks in the vegetative stage and drops significantly once the plant bolts. An established plant can yield 0.5-2 lb dried leaf per season depending on how aggressively you cut it back.
Yield and value: 0.5-2.0 lb dried leaf per established plant per season. Retail: $10-18/lb. Internal link: lemon balm crop page.
Peppermint (Mentha x piperita)
Evidence grade: Strongest clinical evidence of any herb on this list; NCCIH rates evidence as “good” for IBS; controlled trial support for tension headache.
Peppermint is the outlier in this group. The evidence for two specific uses - irritable bowel syndrome (IBS) and tension headache - is genuinely strong by herbal medicine standards.
For IBS: enteric-coated peppermint oil capsules have been tested in multiple randomized controlled trials. A meta-analysis by Khanna et al. (2014) in the Journal of Clinical Gastroenterology analyzed nine trials and found consistent benefit for IBS symptom relief, with peppermint oil outperforming placebo across multiple symptom measures. NCCIH rates this evidence as “good.” The mechanism is understood: menthol relaxes smooth muscle in the gut wall by blocking calcium channels. Enteric coating matters - uncoated capsules release in the stomach and can cause heartburn; the therapeutic effect for IBS requires delivery to the small intestine and colon.
Important caveat: the evidence is for enteric-coated peppermint oil capsules at 0.2-0.4mL per dose, three times daily. That is not a cup of peppermint tea. Tea may have digestive benefit at lower activity levels - it’s been used for digestive discomfort traditionally - but the clinical trial data applies to the capsule formulation specifically.
For tension headache: a controlled trial by Göbel et al. (1994) in Cephalalgia found that topical application of a 10% peppermint oil preparation reduced headache intensity comparably to 500mg acetaminophen. The mechanism is the TRPM8 cold-receptor activation by menthol, which creates a competing sensory signal. This is topical application, not ingestion.
Growing: Peppermint is a sterile hybrid (Mentha x piperita) that spreads by rhizome, not seed. You need to start from a transplant or division. It must be contained - either in a pot or with a root barrier - or it will colonize a significant portion of your garden within two seasons. Harvest before the plant flowers for highest menthol content; menthol concentration drops after flowering. An established bed yields 1-3 lb dried leaf per season.
Yield and value: 1-3 lb dried leaf per established bed per season. Retail: $8-15/lb. Internal links: peppermint crop page, mint crop page.
Lavender (Lavandula angustifolia)
Evidence grade: Some clinical evidence for anxiety from oral preparations; aromatherapy evidence is weaker; NCCIH rates oral lavender as having “some evidence.”
The lavender evidence picture is more complicated than most marketing suggests. There are two distinct claims with different evidence bases: oral lavender preparations and inhaled lavender aromatherapy.
Oral lavender oil: A 2010 trial by Woelk and Schläfke in Phytomedicine tested Silexan, an oral lavender oil preparation standardized to 80mg, against lorazepam (a benzodiazepam) and placebo in patients with generalized anxiety disorder. Silexan showed comparable efficacy to lorazepam in reducing anxiety symptoms, with fewer side effects related to sedation. This is a reasonably well-designed trial. NCCIH acknowledges it, rating the evidence as “some evidence” for oral lavender and anxiety.
Lavender aromatherapy: The inhaled-lavender claim for sleep and anxiety is supported by a large number of studies - but most are small, use inconsistent methods, and are difficult to blind properly (participants know whether they’re smelling lavender). NCCIH rates the aromatherapy evidence as weaker than the oral evidence.
Growing your own lavender and making an essential oil that replicates Silexan is not practical without a distillation setup. A small still costs $150-400 and requires large volumes of plant material - roughly 50-100 lb of fresh lavender flowers to produce one ounce of essential oil. Home distillation is a real hobby but not something you do with a 4x8 bed.
What you can reasonably do: dry lavender flowers for tea (note that culinary lavender - English lavender, L. angustifolia, lower camphor content - is the correct type; do not use ‘Grosso’ or other ornamental types for food), use dried flowers in sachets, or harvest for baking.
Growing: Perennial in zones 5-9, with good drainage critical in zone 5 - wet roots in winter kill lavender faster than cold does. English lavender (L. angustifolia) varieties like ‘Hidcote’ and ‘Munstead’ are the most cold-hardy and have the culinary and medicinal oil profile. Harvest at 50% bud open for highest oil content - fully open flowers have lower volatile compound concentration. Expect 0.25-1.0 lb dried flower per established plant per season.
Yield and value: 0.25-1.0 lb dried flowers per plant per season. Retail: $15-35/lb dried flowers. Internal link: lavender crop page.
Echinacea (Echinacea purpurea, E. angustifolia, E. pallida)
Evidence grade: Mixed; some evidence for modest reduction in cold duration; NCCIH: “some echinacea products may modestly reduce the duration of the common cold, but evidence is inconsistent.”
Echinacea is one of the most-studied herbal supplements in the world. It is also one of the most inconsistently studied, which makes honest characterization difficult.
A 2015 Cochrane systematic review - the most rigorous available summary of the evidence - analyzed 24 randomized trials and concluded that “some evidence” exists that echinacea preparations may reduce the incidence of the common cold, with inconsistent results across trials of varying quality. Effect sizes in positive trials are modest: a reduction in cold duration of roughly half a day to one day. Several high-quality trials found no effect.
Part of the inconsistency comes from species confusion. Echinacea purpurea - the purple coneflower common in garden centers - has different active chemistry than E. angustifolia, which was used in most of the historical North American research and in many European clinical trials. Most commercial products, regardless of what they say on the label, use E. purpurea aerial parts. This is not fraud; it’s a real and ongoing source of trial inconsistency that NCCIH explicitly acknowledges.
What the evidence does not support: preventing colds, treating infections, or boosting immune function as a general claim. The modest cold-duration signal is the extent of what consistent positive trials show.
Growing: Echinacea is a reliable perennial in zones 3-9. E. purpurea is the easiest to grow and most commonly available. It flowers in its first year from transplant and reaches full production in year two. Harvest aerial parts (leaf and flower) at peak bloom; harvest root at 3-4 years for maximum alkylamide content. Root harvest kills the plant, so maintain a stand by leaving some plants unharvested. Yield: 0.5-1.0 lb dried aerial parts per mature plant per season.
Yield and value: 0.5-1.0 lb dried aerial parts per mature plant per season. Retail: $15-28/lb dried herb.
Valerian (Valeriana officinalis)
Evidence grade: Widely used for sleep; clinical evidence is inconclusive; NCCIH: “not enough reliable evidence to know whether valerian is helpful for sleep.”
Valerian is worth honesty. It is one of the most popular herbal sleep aids sold in the United States. It is also one of the least well-supported by the clinical evidence, despite the volume of trials conducted.
A 2010 meta-analysis by Fernández-San-Martín et al., published in Sleep Medicine, reviewed 16 eligible studies and found no consistent evidence of sleep benefit. Multiple individual small trials show positive results. The pattern - many small positive trials, no benefit in larger or higher-quality trials - is a familiar sign of publication bias and underpowered studies inflating effect estimates. NCCIH’s conclusion is the appropriate one: not enough reliable evidence.
This does not mean valerian is inert. The plant contains valerenic acid and other compounds that have demonstrated GABA-modulating effects in vitro. It may well do something in humans. But “may do something” is a different claim than “improves sleep quality,” and the clinical literature doesn’t support the specific claim that most consumers are reading on the label.
Growing: Perennial in zones 4-9. Valerian grows 3-5 feet tall and is a reasonably ornamental plant before harvest. The fresh root smells unremarkable. The dried root smells strongly of sweaty socks - this is isovaleric acid oxidizing as the root dries, and it is completely normal. Harvest root in fall of year two or three for maximum active compound content. Expect 0.25-0.75 lb dried root per mature plant.
Yield and value: 0.25-0.75 lb dried root per plant (years 2-3). Retail: $12-22/lb dried root.
Ashwagandha (Withania somnifera)
Evidence grade: Building clinical evidence for cortisol reduction and stress/anxiety; NCCIH: “promising but more research needed.”
Ashwagandha occupies the “adaptogen” category - a term from traditional medicine meaning roughly “helps the body handle stress” - and the clinical evidence is more developed than most adaptogens. A randomized, double-blind, placebo-controlled trial by Chandrasekhar et al. (2012), published in the Indian Journal of Psychological Medicine, found statistically significant reductions in serum cortisol levels and self-reported stress and anxiety scores in adults taking 300mg ashwagandha root extract twice daily for 60 days. The cortisol finding is notable because it’s an objective biomarker, not just a self-report scale.
Multiple subsequent trials have shown consistent signals for stress and anxiety reduction. NCCIH acknowledges the promising early evidence while noting that larger, longer trials are needed before drawing firm conclusions.
Safety matters here. Ashwagandha may interact with thyroid medications (including levothyroxine), immunosuppressants, and sedative medications. It is contraindicated in pregnancy based on traditional use documentation and limited animal data. Anyone taking prescription medications should check with a physician before using ashwagandha supplements.
The form of ashwagandha used in trials is typically root powder or concentrated root extract at 300-600mg per day. This is achievable from dried and powdered home-grown root.
Growing: Full growing details are on the ashwagandha crop page. The short version: ashwagandha is a subtropical perennial grown as an annual in most of North America. It tolerates poor, dry soil - actually performs better in well-drained sandy or loamy soils than in rich garden beds. Harvest root at the end of the growing season (typically fall). Yield from home cultivation runs 0.25-0.5 lb dried root per plant.
Yield and value: 0.25-0.5 lb dried root per plant per season. Retail: $15-30/lb dried root.
Harvesting and Drying for Medicinal Use
Timing is the most commonly overlooked factor in home herb harvesting. Most medicinal herbs have peak volatile oil and active compound concentration at or just before full bloom. Specific windows:
- Chamomile: harvest when disc florets are fully open and beginning to flatten outward; unopened buds and fully post-peak flowers have lower apigenin content
- Lavender: 50% bud open; fully open flowers have measurably lower essential oil concentration
- Peppermint: just before flower buds open; menthol content drops after flowering begins
- Lemon balm: before flowering; volatile oil content is highest in vegetative growth
For roots (valerian, ashwagandha): fall of the plant’s second or third year for perennials; end of the growing season for ashwagandha grown as an annual.
Drying temperature matters
Lower temperatures preserve volatile compounds. A dehydrator set to 95-110°F retains essential oils better than a 135°F setting - the difference is significant for chamomile, lavender, and peppermint, which contain volatile terpenes that evaporate at higher temperatures. Air drying - bundled stems or spread flowers hung in a warm, dry, shaded location with good airflow - is acceptable for aerial parts (flowers, leaves) and preserves delicate volatile compounds that heat degrades. Drying time is 1-3 weeks depending on humidity and temperature.
Air drying is not suitable for thick roots. Valerian and ashwagandha roots need heat to dry through before they mold internally. Slice roots to 1/4 inch thickness and dry at 110-125°F in a dehydrator until completely dry throughout.
Storage
Brown paper bags or glass jars in a cool, dark location. Clear glass jars on a sunny windowsill look nice and destroy your herbs - UV radiation degrades volatile compounds and oxidizes flavonoids. Dried aerial parts hold potency for 1-2 years. Dried roots hold 2-3 years. Label everything with the harvest date.
Evidence Summary by Herb
| Herb | Primary claim | Evidence grade | NCCIH rating |
|---|---|---|---|
| Peppermint | IBS symptom relief (capsules) | Multiple RCTs, meta-analysis | ”Good evidence” |
| Chamomile | Anxiety reduction | Phase II RCT (Amsterdam 2009) | “Some evidence suggests benefit” |
| Lavender | Anxiety (oral preparations) | RCT (Woelk 2010, Silexan) | “Some evidence” |
| Ashwagandha | Cortisol/stress reduction | Multiple RCTs (Chandrasekhar 2012) | “Promising, more research needed” |
| Echinacea | Cold duration reduction | Mixed RCTs, 2015 Cochrane review | ”Evidence is inconsistent” |
| Lemon balm | Anxiety/sleep | Small, limited trials | ”Insufficient evidence” |
| Valerian | Sleep promotion | Meta-analysis showed no consistent effect | ”Not enough reliable evidence” |
Evidence grades based on NCCIH summaries at nccih.nih.gov, current as of 2025.
What to Grow First
Other herbs worth considering beyond these seven: catnip (Nepeta cataria) - a perennial mint-family herb with documented mild sedative properties used in traditional herbal medicine, easy to grow, and available as a pleasant mild tea; lemon verbena - an intensely lemon-scented perennial (or tender perennial in cooler zones) that makes excellent tea and commands $12-20/lb at specialty stores; and moringa - occasionally called the “miracle tree,” with leaves that are among the most nutritionally dense of any leafy green, growable as an annual in zones 8 and warmer or as a large container plant elsewhere.
If you’re planting a first medicinal herb garden, chamomile + lemon balm + peppermint is the practical starting point. All three have the easiest growing requirements on this list. Chamomile is a direct-sow annual that self-seeds after year one. Lemon balm and peppermint are perennials that establish without much intervention and spread on their own.
That combination also covers the best-evidenced categories: peppermint for digestive use (the one herb on this list where the clinical evidence is genuinely strong), chamomile for the anxiety/calming category (modest but real trial evidence), and lemon balm as a pleasant addition to the tea rotation regardless of its evidence grade.
Echinacea is worth growing if you have a perennial bed that needs filling - it’s a handsome plant (E. purpurea is a common native garden perennial), the growing investment is low, and the cold-duration evidence, while inconsistent, isn’t zero. Just don’t build expectations around it doing more than the trials show.
Valerian and ashwagandha are worth growing if you specifically want the root products. Valerian’s sleep evidence is weak but the root is easy to grow and cheap to produce. Ashwagandha has the strongest stress-evidence trajectory of any herb on this list and is straightforward to grow in most of the country as an annual.
Crop pages: Chamomile - Lavender - Lemon Balm - Peppermint - Ashwagandha - Mint
Related reading: Herb ROI Comparison - culinary herb economics side by side