When to sow calendula

Calendula is a hardy annual, so unlike marigolds (Tagetes) or nasturtiums it doesn't need to wait for the last frost. Sow it straight into the bed from late March, as soon as the soil can be worked, and keep sowing until early August.

Spring sowings flower from late May or June. A second sowing in June or July fills gaps left by early vegetables and gives fresh plants for late summer and autumn, when the first batch is tired. Calendula often sulks in a long hot spell and picks up again when it cools.

In the UK and other mild areas you can also sow in autumn. The young plants overwinter and flower earlier the next year. Indoors, you can start calendula in pots from late March, but it is rarely worth it: direct-sown plants catch up quickly.

Calendula seeds are large, curved and easy to handle. Sow them about 0.4 in deep and cover them well, because light holds back germination. Seedlings appear in five days to two weeks. Use fresh seed if you can: old seed germinates less reliably.

Sow 4 in apart in rows 12 in apart. That makes a dense row for cutting; in a mixed bed, thin to fewer, bushier plants. On rich soil calendula grows very lush, so thin it where it would crowd out vegetables.

Calendula copes with almost any soil, including poor, dry and heavy ground. It only struggles on very wet or very rich soil. It flowers best in full sun but tolerates light shade.

Calendula needs little care. Pinch out the growing tips once the young plants are a few centimetres tall and they branch into bushier plants with more flowers.

Deadhead regularly and it keeps flowering from early summer until the first hard frosts. Water only in long dry spells; it copes with dry soil better than with wet, though it dislikes both extremes.

Leave a few flowers to set seed at the end of the season and calendula will come back on its own the next year, usually without becoming a nuisance.

Calendula makes a good cut flower. Cut the flowers on a sunny morning, once the dew has dried.

The petals are edible and slightly peppery. Scatter them fresh over salads, or use them as a traditional yellow colouring for cheese. To dry them for later, spread the flowers out somewhere warm but shaded: in the sun they quickly lose their colour.

Dried calendula petals are traditionally used for tea and home-made ointments. If you use them for anything medicinal, treat that as folk tradition and ask a pharmacist or doctor about real complaints.

In the UK, calendula is often simply called marigold, pot marigold or common marigold. It is a different plant from the French and African marigolds, Tagetes, which are killed by the first frost. If a recipe or seed packet just says 'marigold', check the botanical name.

Be careful with Cape marigolds (Dimorphotheca and relatives), too. They are also in the daisy family but are not calendula and are not for eating.

Flowers are usually bright orange, but there are cream, pale yellow and pale orange varieties, single or double. Most grow 4–20 in tall; taller types such as 'Indian Prince' reach up to 39 in and are the best for cutting.

Powdery mildew is the most common problem: a white, powdery coating on the leaves. Pull out badly affected plants; a sowing in June or July gives you fresh plants to take over.

Aphids like calendula, and occasionally a virus, such as cucumber mosaic virus, turns up. Remove plants with mottled, misshapen leaves.

Calendula belongs to the daisy family, Asteraceae, with lettuce, sunflowers and marigolds. As a flower it sits outside the vegetable rotation, and it is often sown as a gap-filler or green manure: its taproots loosen the soil.

Calendula is a favourite in mixed planting, next to cabbages, potatoes and outdoor tomatoes, and gardeners plant it near beans and tomatoes hoping it will draw in helpful insects. It certainly attracts pollinators, but we found no trial showing that it protects the crops beside it. That part is tradition.

The practical rule: calendula grows lush on rich vegetable soil, so keep it thinned so it doesn't shade or crowd its neighbours.