Medicinal plants to sow yourself: a garden calendar and uses

In this article 9

A medicinal plant bed is one of the most beautiful corners of a garden: staggered blooms, fragrances, and pollinators throughout the season. Most of these species are also hardy, water-efficient, and undemanding — they grew in cottage gardens long before anyone talked about permaculture.

This guide covers their cultivation: what to sow, when and how to harvest and dry. It does not cover their therapeutic uses, for a reason that must be stated at the outset.

Read this first

The term “medicinal plant” refers to a tradition of use, not safety. Several species in this family are toxic, and some are severely so.

These plants are not a substitute for any treatment. If you experience symptoms, consult a doctor or pharmacist.
Some interact with medications or are contraindicated during pregnancy, breastfeeding, in children, or in the presence of chronic conditions. Always seek professional advice before any internal use.
Some species in our collection are ornamental or toxic and must under no circumstances be consumed: wormwood, rue, tansy, opium poppy. They are grown for their botanical, bee-friendly, or decorative value.
Never use a plant you have not identified with certainty. Several medicinal Apiaceae have deadly look-alikes.

What follows therefore concerns gardening and the passing down of plant heritage — not health advice.

The easy ones, to get started

Hardy, undemanding, and easy to identify. These are the ones to start with.

German chamomile (Matricaria chamomilla) — annual; sow directly in spring or autumn, barely covered: it needs light to germinate. It self-seeds afterward.
Lemon balm (Melissa officinalis) — very easy perennial, with a distinct lemon fragrance. Slow and erratic germination: sow in a seed tray and be patient. Once established, it becomes invasive — give it a confined space.
Calendula (Calendula officinalis) — annual, direct sowing from March to May, with a very long flowering period. Self-seeds.
Thyme and Common sage — Mediterranean perennials. Well-drained, poor soil and full sun; no watering once established. Sow in spring; slow growth in the first year.
Yarrow (Achillea millefolium) — extremely hardy perennial; its flat flower heads are one of the best resources for hoverflies.
Common mallow and marsh mallow — perennials with a long summer flowering period, highly decorative at the back of a border.

The perennials to plant once

Slower growth, but they become established for many years.

Purple coneflower (Echinacea purpurea) — spectacular and much visited by pollinators. Requires cold stratification for 4 to 8 weeks to germinate properly: see Cold stratification.
Common valerian (Valeriana officinalis) — tall, prefers cool soil. Surface sowing; light is necessary for germination.
Garden angelica (Angelica archangelica) — imposing biennial, up to two metres tall. Its seeds quickly lose their ability to germinate: sow them fresh, preferably in autumn.
White horehound (Marrubium vulgare) — perennial of dry, poor soil, with fuzzy silver foliage.
Dandelion (Taraxacum officinale) — yes, it is intentionally sown: leaves for salads, the root, and it is one of the earliest sources of nectar in spring. Incidentally, our emblem.
Nettle (Urtica dioica) — keep it confined to a designated corner. A host plant for many butterflies, a basis for liquid fertilizer, and an excellent compost activator.

Exotic plants and curiosities

Holy basil Tulsi (Ocimum tenuiflorum) — grown as an annual in our climate, perennial in a conservatory. A very distinctive fragrance, somewhere between clove and pepper.
Stevia (Stevia rebaudiana) — leaves with intense sweetening power. Tender: grow in a pot and bring indoors for the winter. Delicate germination; sow on the surface in a warm place.
Indian ginseng (Withania somnifera) — tropical shrub, grown in pots in our climate.
Bay laurel (Laurus nobilis) — culinary shrub. Very slow germination, taking several months. Not to be confused with oleander, which is toxic.

Sowing calendar

Period	Species	Method
February – March	Echinacea (after stratification), thyme, sage, stevia	Under cover, in a warm place
March – May	Chamomile, calendula, yarrow, white horehound, mallow	Direct sowing
April – June	Lemon balm, valerian, marshmallow, holy basil	Sow in a seed tray, then transplant
August – September	Chamomile, calendula, yarrow	Direct sowing, early flowering the following year
October – November	Angelica (fresh seeds), perennials requiring stratification	Sow outdoors; the cold breaks dormancy

One point that explains many failures: many medicinal plants have very fine seeds that require light to germinate — chamomile, valerian, stevia, mallow. Do not bury them: simply press them against the moist substrate.

Harvesting and drying

When to harvest

The timing depends on the plant part, because the concentration of active compounds varies throughout the cycle.

Leaves — before flowering, when the plant concentrates its resources in them.
Flowers — right at the beginning of flowering, freshly opened.
Entire aerial parts — in full bloom.
Roots — in the autumn of the second year, when the plant has drawn its reserves down into the roots.
Seeds — when fully ripe, before dispersal.

In all cases: in the morning, after the dew has evaporated, in dry weather. This is when the essential oils are most concentrated.

Drying properly

In complete shade — light degrades the active compounds and causes the colors to change.
In a well-ventilated place, between 20 and 35°C. An airy attic is ideal.
In small bunches hung upside down, or laid flat on racks for delicate flowers.
Do not pile them up — air must circulate between the stems, otherwise they will mold in the center.
The test: a dried plant snaps cleanly instead of bending. Allow anywhere from a few days to two weeks.

Storing

In airtight glass jars, protected from light, with a label and date. Leaves and flowers retain their qualities for about a year, roots for two to three years. One reliable sign: if the scent has disappeared, the plant is no longer worth much.

Their place in the garden

A medicinal herb bed is not just a utilitarian space: it is one of the best reservoirs of beneficial insects in a vegetable garden.

Group plants by water requirements — Mediterranean plants (thyme, sage, horehound) on one side, in well-drained, poor soil; moisture-loving plants (lemon balm, valerian, angelica) on the other. Mixing them is the costliest mistake.
Do not fertilize. Essential oils become concentrated in a mildly stressed plant. Excess nitrogen produces abundant, bland foliage.
Contain invasive plants — lemon balm, nettle, mint: in a buried pot or with a barrier.
Let it flower — even if you harvest the leaves before flowering, leave a few plants in bloom for pollinators. See Combining flowers in the vegetable garden.
Place them in zone 1 or 2 — near the house, where you pass by. A medicinal plant at the back of the property will never be harvested.

Frequently asked questions

Can medicinal plants be grown in pots?

Yes, especially Mediterranean species — thyme, sage, and horehound — which thrive in well-drained, poor substrates. Stevia and Indian ginseng even require them in our climate. See Balcony vegetable garden.

Why aren’t my lemon balm seeds germinating?

Three possible causes: they were sown too deeply (they need light), the substrate is too cold, or they are simply slow to germinate — lemon balm can sometimes take three to four weeks. Do not discard the seed tray too soon.

Do you need a physic garden to do it properly?

No, the layout is up to you. What matters is grouping them according to their water needs and ensuring accessibility. Many medicinal plants fit very well along the edges of vegetable gardens or in ornamental beds.

Can you harvest their seeds?

Yes, and for most of them it is simple: chamomile, calendula, yarrow, mallow, and lemon balm produce abundant seeds. Beware of angelica, whose seeds do not store well. See How to store your seeds.

Do these plants attract pests?

Quite the opposite. Their essential oils interfere with many insects’ ability to locate plants by scent, and their flowers feed beneficial insects. This is one of the reasons they were traditionally planted along the edges of vegetable gardens.

Key takeaway

Start with chamomile, calendula, lemon balm, and thyme: four unambiguous species that are easy to grow and dry. Group them according to their water needs, do not fertilize, harvest in the morning, and dry in the shade. For any internal use, seek professional advice — growing and treating are two different professions.