Calendulas (Calendula officinalis), commonly known as pot marigolds, are cheerful, easy-to-grow hardy annuals that bring vibrant colour to gardens, borders, containers, and vegetable plots alike. Their daisy-like blooms range from creamy white and soft apricot through to rich golden yellow and deep orange, flowering prolifically over a long season.
Beyond their ornamental appeal, calendulas are genuinely useful plants. Their petals are edible, lending colour and a mildly tangy flavour to salads, soups, and rice dishes, and they have a long history of use in herbal remedies and cosmetics. In the vegetable garden, calendulas are highly valued as companion plants, attracting beneficial insects such as hoverflies and bees while deterring common pests.
Calendulas are cool-season growers, performing best in spring and autumn and tolerating light frosts. They can be grown as annuals almost universally, or as short-lived perennials in climates with very mild winters. Their ease of cultivation and multi-purpose nature make them a favourite for gardeners of all experience levels.
How To Grow
Sowing Seeds Calendulas are best sown directly into the ground or into trays for transplanting. Sow seeds approximately 1 cm deep in well-drained, moderately fertile soil. They germinate readily at soil temperatures of 10–20°C, typically within 7–14 days. For a long flowering season, make successive sowings every 3–4 weeks from early spring through to late summer.
Position and Soil Choose a position in full sun or light partial shade. Calendulas are adaptable to most soil types but perform best in well-drained, moderately fertile soil. Overly rich soil encourages leafy growth at the expense of flowers. If your soil is very heavy, work in some grit or coarse sand to improve drainage.
Planting Out If starting indoors, transplant seedlings outdoors once they have developed a few true leaves and after hardening off for 7–10 days. Space plants 20–30 cm apart in rows 30 cm apart to allow good airflow.
Watering and Feeding Water regularly but avoid waterlogging. Calendulas have moderate water needs and some drought tolerance once established. Feed with a balanced liquid fertiliser monthly during the growing season to support continued flowering. Avoid excessive nitrogen, which promotes foliage over blooms.
Deadheading Regularly deadhead spent blooms to encourage continuous flowering and prevent the plant from setting seed too early. If you wish to collect seed for next year, allow some late-season blooms to mature fully on the plant.
Harvesting
When to Harvest Calendula flowers are ready to harvest when the blooms are fully open and the petals are well extended. Pick flowers in the morning after any dew has dried but before the heat of the day sets in, as this is when they are at their freshest and most aromatic.
How to Harvest Hold the stem just below the flower head and give it a gentle downward twist to snap it cleanly from the plant, or use sharp scissors or secateurs to cut the stem 2–3 cm below the flower head. Frequent harvesting encourages the plant to produce more blooms, so do not be afraid to pick regularly.
Edible Use Calendula petals are edible and can be used fresh as a garnish in salads, scattered over rice dishes, or stirred into soups and stews for colour. They have a mildly tangy, slightly bitter flavour. Only the petals are typically eaten; the green parts of the flower head can be bitter and resinous.
Drying for Storage To dry calendula flowers for later use, spread them in a single layer on a clean surface in a warm, well-ventilated spot away from direct sunlight. Once fully dry (typically 1–2 weeks), store in an airtight container in a cool, dark place. Dried petals can be used in herbal preparations, teas, or as a natural dye.
Common Problems
Powdery Mildew Powdery mildew is one of the most common issues affecting calendulas, particularly in warm, dry conditions with poor air circulation. It presents as a white, powdery coating on the leaves and stems. Improve airflow by spacing plants correctly, avoid overhead watering, and remove affected foliage promptly. In severe cases, treat with a dilute solution of bicarbonate of soda or a suitable organic fungicide.
Aphids Aphids, particularly blackfly, can cluster on new shoots and flower buds, weakening growth. Calendulas can actually attract aphids in the vegetable garden as a trap crop, drawing them away from more valuable plants. Treat infestations by spraying with a strong jet of water or applying an insecticidal soap solution. Encourage natural predators such as ladybirds and hoverflies.
Slugs and Snails Young seedlings are vulnerable to slug and snail damage, especially in cool, moist conditions. Use physical barriers such as copper tape or crushed eggshells around plants, or apply organic slug pellets approved for use around edible crops.
Botrytis (Grey Mould) In humid conditions, botrytis can cause stems and petals to develop a grey, fluffy mould. Remove affected plant material immediately, improve air circulation, and avoid wetting foliage when watering.
Whitefly Whitefly can occasionally affect calendulas in sheltered growing conditions. Sticky yellow traps and insecticidal soap sprays are effective controls. Encouraging beneficial predatory insects through companion planting helps reduce populations naturally.
