Calendula Monograph

Calendula Monograph

Calendula officinalis

Quick Reference

Common names: calendula, pot marigold, common marigold, Scotch marigold, ruddles
Latin name: Calendula officinalis
Plant family: Asteraceae (daisy family)
Parts used: flowers (petals and whole flower heads)
Primary actions: vulnerary, anti-inflammatory, antimicrobial, lymphatic, astringent
Best preparations: infused oil, salve, cream, infusion (tea), tincture
Safety rating: extremely safe, suitable for all ages
Grown at Wild Clover Farm: yes — a garden staple

Botanical Description and Identification

Calendula (Calendula officinalis) is one of the most widely used medicinal herbs in the world. Often called pot marigold, it is not a true marigold (Tagetesspecies) but a member of the daisy family. Its bright orange and yellow flowers have been valued in gardens and healing traditions for centuries.

Plant Characteristics

Flowers:
Calendula flowers are the primary medicinal part of the plant. Blooms range from bright orange to golden yellow and are daisy-like in appearance, typically measuring 2 to 4 inches across. Each flower head consists of multiple layers of ray florets surrounding a central disc. Fresh flowers have a slightly sticky or resinous texture and a mild, pleasant herbal scent. Flowers open in the morning and close at night or during cloudy weather.

Leaves:
Leaves are oblong to lance-shaped, measuring 2 to 6 inches long. They are pale to medium green, slightly fuzzy, and arranged alternately along the stem. Leaves may feel mildly sticky to the touch.

Stems:
Stems are hollow, somewhat succulent, and light green, often with a slight purple tinge. Plants branch freely from the base and may become woody near the crown during long growing seasons.

Growth habit:
Calendula is typically grown as an annual, though it may behave as a short-lived perennial in mild climates. Plants grow 12 to 24 inches tall with a bushy, branching form and flower continuously from spring through frost under favorable conditions.

Important Identification Note

Calendula is often confused with common garden marigolds (Tagetes species). While both are sometimes called marigold, Tagetes plants have a strong, pungent odor and are not used medicinally in the same way. Always confirm you are growing Calendula officinalis for medicinal use.

Native Range and Habitat

Calendula is native to southern Europe and the Mediterranean region. It has been cultivated for centuries and is now grown worldwide. In some regions, it has naturalized and may be found along roadsides or in disturbed areas, though it is most commonly cultivated in gardens.

Calendula thrives in temperate climates and performs best during cool seasons. It tolerates light frost and often blooms vigorously in spring and fall. In mild winter regions, it may flower nearly year-round.

Growing Calendula

Climate and Growing Conditions

Calendula grows well in USDA hardiness zones 2 through 11 and is especially well suited to cool-season cultivation.

Sunlight:
Full sun is ideal in cooler climates. In warmer regions, afternoon shade helps prevent heat stress. A minimum of four to six hours of direct sunlight supports good flowering.

Soil:
Calendula prefers well-drained, moderately fertile soil with a pH between 6.0 and 7.0. It tolerates poor to average soil but performs poorly in overly rich or waterlogged conditions.

Temperature:
Ideal growing temperatures range from 60 to 70 degrees Fahrenheit. Flower production may slow when temperatures consistently exceed 85 degrees.

Water:
Provide moderate, consistent moisture. Water when the top inch of soil dries, and avoid overhead watering to reduce fungal issues. Plants become more drought tolerant once established.

Growing From Seed

Calendula is exceptionally easy to grow from seed and is well suited to beginning gardeners.

When to plant:

• Spring: sow seeds two to four weeks before the last frost
• Fall: sow six to eight weeks before the first frost for late-season blooms
• Succession sowing every two to three weeks encourages continuous harvest

How to plant:

• Prepare soil by loosening it to a depth of about 6 inches.
• Sow seeds one-quarter to one-half inch deep.
• Space seeds 6 to 12 inches apart, or sow thickly and thin later.
• Keep soil consistently moist until germination.

Seeds typically germinate within 5 to 14 days.

Seed notes:
Calendula seeds are crescent-shaped and easy to recognize. Fresh seeds germinate most reliably and remain viable for three to five years when properly stored. Plants readily self-seed if flowers are allowed to mature.

Site Selection and Care

Spacing:
Space plants 8 to 12 inches apart for medicinal production. Adequate air circulation helps prevent fungal issues.

Fertilizing:
Calendula is a light feeder. Compost incorporated at planting is usually sufficient. Excess nitrogen promotes leaf growth at the expense of flowers.

Maintenance:
Regular harvesting encourages continued blooming. Deadhead spent flowers if not harvesting all blooms. Mulch lightly to retain moisture, keeping mulch away from the plant crown.

Pests and diseases:
Calendula is generally pest resistant. Aphids and powdery mildew may appear under poor growing conditions but are easily managed with proper spacing and watering practices.

Harvesting Calendula

What to Harvest and When

The flowers are the sole focus of medicinal harvest.

Harvest flowers when they are fully open and in prime condition. Peak bloom corresponds to peak medicinal potency. Harvest regularly throughout the growing season to encourage continued flowering.

Best timing:

• Midmorning, after dew has dried
• Avoid early morning or midday heat

Harvest two to three times per week during peak production.

Harvesting method:
Pinch or snip off the entire flower head just below the base, including the green calyx. Flowers should be handled gently and processed promptly after harvest.

Drying and Storage

Calendula flowers have a high moisture content and must be dried carefully to prevent mold.

Dehydrator method:
Spread flowers in a single layer and dry at 95 to 100 degrees Fahrenheit for 12 to 24 hours, until completely crisp.

Air-drying method:
Dry flowers on screens in a warm, dark, well-ventilated space, turning daily. Drying typically takes three to seven days, depending on humidity.

Properly dried flowers are crisp, retain bright color, and have no residual moisture.

Store dried flowers in airtight containers away from light and heat. Shelf life is one to two years.

Traditional and Modern Uses

Calendula is best known as a wound-healing and skin-support herb.

Primary Uses

• Supports tissue repair and wound healing
• Reduces inflammation and irritation
• Provides gentle antimicrobial protection
• Supports lymphatic movement
• Soothes dry, damaged, or sensitive skin

Calendula has been used traditionally for cuts, scrapes, burns, rashes, eczema, diaper rash, and minor skin infections. Internal use has also been recorded for digestive and inflammatory conditions, though topical use remains most common.

Energetics and Traditional Classification

• Temperature: cool to neutral
• Moisture: moist
• Taste: mildly bitter, slightly sweet
• Tissue affinities: skin, lymphatic system, digestive tract, liver
• Energetic indications: heat, inflammation, irritation, stagnation, slow or compromised tissue repair

Calendula is traditionally classified as a vulnerary lymphatic alterative, gently supporting the movement of lymph while promoting tissue regeneration. It is especially indicated where chronic inflammation, poor circulation, or lymphatic congestion contribute to delayed healing or recurrent skin conditions.

Primary Herbal Actions

• Vulnerary: supports wound healing and tissue regeneration
• Anti-inflammatory: reduces heat, redness, and irritation internally and externally
• Lymphatic: promotes lymphatic movement and drainage
• Antimicrobial: exhibits antibacterial and antifungal activity
• Alterative: supports gradual detoxification and tissue health
• Astringent (mild): tones tissues without excessive drying
• Cholagogue (mild): supports bile flow and digestive function
• Emmenagogue (mild): traditionally associated with menstrual regulation  

Preparation Methods

Calendula Infused Oil

Calendula-infused oil forms the base of most calendula preparations.

Dried flowers are infused in a carrier oil such as olive, sunflower, or sweet almond oil using either a slow folk method or gentle heat. Flowers must be completely dry to prevent spoilage. Properly prepared oil stores for one to two years.

Calendula Salve or Balm

Calendula salve is commonly used for skin care and first aid. Infused oil is gently heated with beeswax and poured into jars or tins. Salves are used for cuts, scrapes, burns, dry skin, and irritation.

Calendula Tea

Calendula tea may be used internally for digestive inflammation or externally as a wash or compress for skin conditions. Tea is prepared by steeping dried flowers in hot water for 10 to 15 minutes and straining well.

Safety and Contraindications

Calendula is one of the gentlest medicinal herbs and is considered extremely safe.

• Safe for infants, children, adults, and the elderly
• Safe during pregnancy and breastfeeding
• Safe for long-term topical use
• No known drug interactions

Rare allergic reactions may occur in individuals sensitive to plants in the Asteraceae family. Perform a skin patch test if concerned.

Calendula is appropriate for home first aid but does not replace medical care for serious wounds or infections.

Wild Clover Farm Notes

At Wild Clover Farm, calendula is grown throughout the garden in herb beds, vegetable plots, and cutting gardens. It is harvested regularly throughout the season and forms the foundation of many skin-care preparations.

Calendula self-seeds readily when flowers are allowed to mature, creating a reliable and low-maintenance supply year after year. Cool-season plantings in spring and fall consistently produce the most abundant and vibrant blooms.

Oklahoma/Zone 7 Growing Notes

• Cool-season annual and struggles in Oklahoma's brutal summer heat (95°F+)
• Two-season strategy: Spring planting (March) for April-June bloom; fall planting (August) for Sept-Nov bloom
• Harvest heavily before heat (late May/early June) then replace with fall crop
• Self-sows moderately; volunteers often overwinter as small plants, bloom early spring
• Plant calendula on the east side of taller plants for afternoon shade protection during late spring heat waves

Foraging:

• Primarily cultivated rather than wild-foraged
• Harvest flowers during full bloom on dry days
• Pinch blossoms regularly to encourage continued flowering
• Use only pesticide-free garden plants
• Do not substitute with ornamental marigolds (Tagetes spp.)

Common Questions

Is calendula safe for open wounds?
Yes. Calendula is traditionally used on clean, open wounds to support tissue repair and help prevent infection.

Can calendula be used long term?
Yes. Calendula is gentle and appropriate for long-term internal or external use, including for children and sensitive individuals.

Is calendula the same as marigold?
Calendula (Calendula officinalis) is sometimes called pot marigold but is distinct from ornamental marigolds (Tagetes species), which are not interchangeable medicinally.

References and Further Reading

• Hoffmann, David. Medical Herbalism
• Wood, Matthew. The Earthwise Herbal
• Gladstar, Rosemary. Herbal Healing for Women
• Chevallier, Andrew. Encyclopedia of Herbal Medicine  

Disclaimer

This information is provided for educational purposes only and is not intended to diagnose, treat, cure, or prevent disease. Always consult a qualified health care provider before using herbal products for serious conditions.