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Calendula

Calendula officinalis

FlowersFrost Hardy

Cheerful pot marigold with edible petals and medicinal properties. Self-seeds readily and attracts beneficial hoverflies.

Overview

SunFull Sun
WaterLowCalculate watering amount
Height30–60 cm
Spread45 cm
Spacing30 cm
Row Spacing45 cm
Germination5–14 days
To Harvest35–55 days

Companion Planting

Bad Companions

None

Toxicity

SeverityNon-toxic

Calendula officinalis is non-toxic to humans, dogs, and cats (ASPCA-listed as safe); petals are edible and used in culinary and herbal applications. Individuals with Asteraceae/daisy family allergies may experience contact dermatitis.

Planting Tips

LocationFull sun to partial shade; tolerates light afternoon shade in hot climates.
SoilAverage, well-drained soil with a pH of 6.0–7.0; tolerates poor soil but thrives in moderately fertile loam.
Sowing Depth1 cm
Planting Depth5 cm
WateringWater moderately, allowing the top few centimeters of soil to dry between waterings; drought-tolerant once established but blooms best with consistent moisture.

1 cm of water per m² equals 10 liters. Use the Watering Calculator for exact amounts.

FertilizingLight feeder — a single application of balanced fertilizer at planting is sufficient; excessive nitrogen promotes foliage over flowers.

Care Tip: Deadhead spent blooms regularly to encourage continuous flowering through the season; calendula often self-sows if a few seed heads are left to mature.

Common Pests

Aphids

Symptoms: Clusters of small green or black insects on stems and buds; sticky honeydew residue and curled or distorted new growth.

Treatment: Spray with a strong jet of water or apply insecticidal soap; neem oil works for heavier infestations.

Prevention: Encourage beneficial insects such as ladybugs and lacewings; avoid over-fertilizing with nitrogen.

Whiteflies

Symptoms: Tiny white flying insects on leaf undersides; yellowing leaves and sticky honeydew leading to sooty mold.

Treatment: Apply insecticidal soap or neem oil, targeting the undersides of leaves; yellow sticky traps reduce adult populations.

Prevention: Inspect new plants before introducing them to the garden; maintain good air circulation around plantings.

Slugs and Snails

Symptoms: Irregular holes in leaves and slime trails on foliage, especially on young seedlings overnight.

Treatment: Hand-pick at dusk or use iron-phosphate-based slug pellets; beer traps can reduce local populations.

Prevention: Remove garden debris and mulch away from stems; use copper tape barriers around beds.

Common Diseases

Powdery Mildew

Symptoms: White, powdery fungal coating on leaves and stems, leading to leaf yellowing and reduced vigor.

Treatment: Remove affected foliage and apply a sulfur-based or potassium-bicarbonate fungicide; neem oil can help in mild cases.

Prevention: Ensure good air circulation by spacing plants 20–30 cm apart; avoid overhead watering and densely shaded locations.

Downy Mildew

Symptoms: Yellow or pale patches on upper leaf surfaces with grayish-purple fuzzy growth on the undersides.

Treatment: Remove and destroy infected plant material promptly; apply a copper-based fungicide if the disease persists.

Prevention: Water at the base of plants in the morning so foliage dries quickly; provide adequate spacing for airflow.

Leaf Spot (Alternaria / Cercospora)

Symptoms: Dark brown or black circular spots on leaves, sometimes with concentric rings, leading to premature leaf drop.

Treatment: Remove and discard affected leaves; apply a copper-based or chlorothalonil fungicide for severe outbreaks.

Prevention: Practice crop rotation and avoid wetting foliage; clean up plant debris at the end of the growing season.