What's the difference between Calendula marigolds and Tagetes marigolds?

Two unrelated plants share the name. Calendula officinalis (pot marigold, English marigold) — hardy annual, clear yellow or orange daisy-like flowers, edible petals, traditional UK cottage-garden plant. Tagetes patula and T. erecta (French and African marigolds) — frost-tender annuals from Mexico, brighter and more varied colours, traditional bedding plants. Different family, different growing requirements; just confusingly the same name.

Do marigolds really help tomatoes?

Yes, but only Tagetes — and only against root-knot nematodes, a pest mostly affecting greenhouse tomato beds where the same soil has been used for years. Tagetes patula secretes alpha-terthienyl which kills the nematodes. The marigolds beside tomatoes general claim is partly true for greenhouse soil; less true outdoors where root-knot nematodes aren't a major UK problem. Calendula has no such effect.

Are calendula petals edible?

Yes — pluck the petals from open flowers and sprinkle on salads, rice, soups, or use to colour butter and cheese. They have a mild, slightly resinous flavour. The whole flower is edible but the centre disk gets bitter. Sometimes called poor man's saffron — colour without the cost.

When should I sow marigolds in the UK?

Calendula: March to April direct outdoors; can also be sown in autumn (September) for early flowers the following spring. Tagetes: late March to early May indoors in modules; plant out after the last frost (mid-May south, early June north). Don't sow Tagetes outdoors before mid-April; cold wet soil rots the seed.

Why are my marigolds not flowering?

Likely causes: too much shade (both species want sun for 6+ hours a day); over-feeding (rich soil pushes leaves at the expense of flowers); seed heads forming (deadhead religiously); or for Tagetes, planted out too early when nights were still cold (the check stays with the plant). They want lean, sunny, deadheaded conditions.

Do marigolds self-seed?

Calendula yes, prolifically — once you have it, you have it for the next several years from self-sown seedlings on bare soil each spring. Tagetes barely — fresh sowing each year is the norm. Calendula self-seedlings often grow more vigorously than nursery-sown plants and crop earlier.

Marigold (Tagetes)

Tagetes patula

ornamental☀️ full-sun🪴 loam📏 small🌡️ RHS H4–H5

📋Quick Facts

Water

💧💧 Average watering

Hardiness

Zone 2-11

About

Sow marigold seed direct outdoors from March onwards, or in modules from February — the name marigold covers two unrelated plants in UK gardens. Calendula officinalis (pot marigold, English marigold) is a fully hardy annual (RHS H4) with edible petals that self-seeds happily across British gardens. Tagetes patula (French marigold) and T. erecta (African marigold) are frost-tender annuals (RHS H1c) usually grown for summer bedding and tomato companion-planting in greenhouses. Both are easy, prolific and reliable. Calendula in clear yellow and orange; Tagetes in fiery orange, yellow and mahogany. Tagetes suppresses root-knot nematodes in greenhouse tomato beds. Both attract pollinators and hoverflies that prey on aphids — useful allies for the wider veg patch.

Top tip

Marigolds are easy from seed; plant in sun, deadhead regularly and they will flower for months.

Also known as: Tagete / cravo-túnico, Clavel de moro / tagete, Œillet d’Inde (Tagetes), Marigold (Tagetes), Aksamitka (Tagetes), Studentenblume (Tagetes), Tagetes patula

How to grow marigold (tagetes)

1
Pick the right marigold for the job
Calendula officinalis (pot marigold) for the kitchen garden, edible petals, and self-seeding cottage-garden look. Tagetes patula (French marigold) for tomato beds and summer bedding. Tagetes erecta (African marigold) for big show flowers. Each grows differently — don't mix them up.
2
Sow Calendula direct from March
Hardy enough to sow outdoors from March in southern England, April further north. 1 cm deep, scatter or in rows. Germination in 10–14 days. Calendula will also self-sow from previous-year plants once established.
3
Sow Tagetes indoors from late March
Frost-tender — start in modules at 18°C. Plant out after the last frost (mid-May south, early June north). Don't be tempted to sow Tagetes outdoors early; cold soil rots the seed.
4
Thin to spacing
Calendula 30 cm apart for full-size plants; 15 cm for cut-and-come-again. Tagetes 20 cm apart for French types; 30 cm for African types.
5
Pinch out the tip
When plants are 15 cm tall, pinch out the growing tip to encourage branching. Both calendula and tagetes flower far more from pinched plants.
6
Deadhead through summer
Cut spent flowers back to the next bud or side-shoot. Both species stop flowering when seed heads form. Picking calendula for vases or to use the petals in cooking has the same effect.
7
Use Tagetes as a tomato companion
Plant French marigolds in or beside greenhouse tomato beds. Tagetes patula roots secrete alpha-terthienyl which suppresses root-knot nematodes — a real, evidence-based companion-planting effect (not folklore). Particularly useful if you've grown tomatoes in the same greenhouse soil for several years.
8
Save calendula seed in autumn
Calendula comes true from open-pollinated seed. Let some flowers go to seed in autumn; gather the curved seed clusters when dry; store in a paper envelope. Self-sown seedlings the following spring are often the most vigorous.

Common questions

Pest Resilience

4/5 — Good resilience

Aromatic foliage deters many pests; useful companion plant.

Companion Planting

Grows well with

Tomato Pepper Courgette Potato Cucumber

Visual Characteristics

🍳

Culinary

Culinary Use

Salad garnish, infused butter, rice colouring, herbal tea, edible decoration

The marigold (tagetes) year in your garden

Dispatching imaginary bots to check your garden out...

What to do now

How to Propagate

🌰Seed

Easy

Hardiness Zones

H1a (tender)H7 (very hardy)

H1a

H1b

H1c

RHS H4–H5

USDA 7 equivalent