At a glance
| Botanical name | Tagetes patula (French), T. erecta (African), T. tenuifolia (signet) |
|---|---|
| Family | Asteraceae (aster family) |
| Type | Warm-season annual; killed by frost |
| USDA zones | Grown as a summer annual everywhere; killed by frost |
| Mature size | About 6–8 in (signet), 6–18 in (French), up to 3–4 ft (African) |
| Light | Full sun, 6+ hours of direct sun |
| Soil | Well-drained; pH 6–7 (University of Minnesota Extension); tolerates drought better than wet soil |
| Bloom | Early summer to frost with deadheading |
| Native range | Mexico and Central America (University of Minnesota Extension; NC State lists Mexico and Guatemala for French marigold) |
| Deer | Deer resistant per Clemson HGIC and NC State Extension; strongly scented foliage |
| Planting | After last frost; start indoors 4–6 weeks ahead (about 8 for African), per Clemson HGIC |
Types of marigolds: French, African, and signet
Nearly every marigold sold in garden centers belongs to one of three Tagetes species. They share the same basic care but differ in size, flower form, and how they handle cool or wet weather, so it pays to know which one is in the six-pack.
| Type | Species | Height | Flowers | Strengths | Watch for |
|---|---|---|---|---|---|
| French | Tagetes patula | 6–18 in | Single, anemone or crested, up to 2 in; yellow, orange, mahogany-red, bicolor | Per Clemson HGIC, holds up better in rainy weather than African types; UF/IFAS finds French cultivars effective against the widest range of nematodes | Needs deadheading unless a self-cleaning variety |
| African (American) | T. erecta | Up to 3–4 ft (compact series 12–16 in) | Large doubles, up to 4–5 in | The showiest; good for background plantings and cutting | Slower from seed; tall types may need staking; blooms rot easily in humid weather (University of Minnesota Extension) |
| Signet | T. tenuifolia | About 6–8 in | Small single flowers, about 1 in | Lacy, lemon-scented foliage; edible flowers | Less showy from a distance |
Despite the common name, African marigold comes from Mexico and Central America, like the other two; University of Minnesota Extension says the name comes from a trade route through northwest Africa. Clemson HGIC lists 'Lemon Gem' and 'Golden Gem' as common signet cultivars. Pot marigold (Calendula officinalis) is a different plant entirely; see the FAQ below.
Wondering whether yours will come back? The common garden marigolds are grown as annuals everywhere (Clemson HGIC notes a different species, Mexican marigold, is a perennial shrub in zones 8–11); the site's page on whether marigolds are perennial covers the self-seeding exceptions.
When to plant marigolds
Marigolds do not tolerate frost, and seedlings caught by a late freeze have to be replaced. Per Clemson HGIC, the ideal time to plant is after the last spring frost; University of Minnesota Extension direct-seeds once soil reaches 65°F. Find your average last frost date, then work backward.
| Method | French and signet | African |
|---|---|---|
| Start seed indoors | 4–6 weeks before last frost (Clemson HGIC) | About 8 weeks before planting out (Clemson HGIC) |
| Sow directly outdoors | After last frost; works well | Possible, but bloom comes late in short-season areas |
| Transplant outdoors | After the danger of frost has passed, once seedlings are hardened off | |
Per Clemson HGIC, marigold seed sown about ¼ inch deep germinates in 5–7 days; University of Minnesota Extension gives 5–8 days at 70–75°F. Do not start seed too early: fast-growing seedlings outgrow small cells. The site's seed starting timeline calculator sets indoor sowing dates from your frost date.
In short-season areas, starting African types indoors early matters most, since they take longest from seed. Per Clemson HGIC, if signet marigolds slow down in midsummer, shearing them back by one-third encourages more bloom in cooler weather.
How to plant marigold seeds and transplants
- Start seeds indoors (optional). Sow about ¼ inch deep in a seed-starting mix at 70–75°F and expect sprouts in 5–8 days. Give seedlings strong light so they stay stocky.
- Harden off. Over about a week, move seedlings outdoors for progressively longer periods. The site's guide to hardening off seedlings lays out a day-by-day schedule.
- Pick a site in full sun with soil that drains well. Waterlogged clay gives the worst results; use a raised bed or container there.
- Space plants for air flow (table below). UC IPM notes botrytis is worst on crowded plants with poor air circulation.
- Pinch young plants. Per University of Minnesota Extension, pinching off the top while the plant is small promotes more branches and a bushier plant.
- Water in well and keep soil evenly moist for the first couple of weeks while roots establish (Clemson HGIC).
| Type | Spacing |
|---|---|
| French | 8–10 in apart (Clemson HGIC) |
| Signet | Fairly close together (University of Minnesota Extension) |
| African | 12–16 in apart (Clemson HGIC); at least 1 ft (University of Minnesota Extension) |
Sun, soil, and water
Light. Per Clemson HGIC and University of Minnesota Extension, marigolds need full sun, 6 or more hours a day; University of Minnesota says full sun all day for blooms all season. NC State Extension notes French marigold tolerates partial shade, but bloom is best in sun.
Soil. Per University of Minnesota Extension, the ideal pH is 6–7, and marigolds tolerate drought better than overly wet soil, so drainage is critical; work compost or sand into heavy soil. Clemson HGIC gives a range of 5.5–7.0 and notes leaves may develop bronze speckling below pH 5.5.
Water. Per Clemson HGIC, aim for about 1 inch of water per week, watering deeply once a week in dry weather and letting the soil dry somewhat between waterings. NC State Extension calls French marigold drought tolerant once established. Water at the base: UC IPM notes botrytis infects after plants stay wet for 6 or more hours and recommends drip irrigation to avoid wetting foliage.
Fertilizing marigolds
Marigolds are light feeders. University of Minnesota Extension recommends working a balanced general-purpose fertilizer into the soil at planting and nothing after; too much fertilizer produces foliage at the expense of blooms. Clemson HGIC suggests a slow-release fertilizer for annuals at planting if you have no soil test. Container plants, which lose nutrients to watering, may need a light feeding later.
Deadheading and the midsummer cutback
Deadheading keeps marigolds blooming because a plant that sets seed slows flower production. Clemson HGIC advises removing old flowers as they fade for continued bloom, and University of Minnesota Extension notes deadheading isn't required but helps greatly, partly because the blooms rot easily in humid weather. The site's deadheading guide covers technique across common annuals.
Signet marigolds may slow down in the hottest part of summer. Per Clemson HGIC, shearing them back by about one-third at that point encourages a fresh flush of bloom in cooler weather. Tall African types may need staking to stay upright in storms.
How to save marigold seeds
- Late in the season, stop deadheading a few of the best flowers and let them dry fully on the plant. The petals should be brown and papery, not just wilted.
- Pull off the dry head, hold it over a paper bag, and peel back the petals. The seeds are the long, thin, dark structures packed at the base of the flower head.
- Spread the seeds indoors to dry, then store them in a labeled envelope in a cool, dry place.
Per Clemson HGIC, save seed only from open-pollinated cultivars; hybrids may be sterile or produce offspring that don't resemble the parent.
Marigolds as pest control: what the evidence supports
Root-knot nematodes: yes, with conditions. Per UF/IFAS Extension, marigold roots release alpha-terthienyl, and marigolds can suppress root-knot nematodes (Meloidogyne spp.), which damage many vegetable, fruit and ornamental crops. The effect requires a dense planting grown as a cover crop at least two months before the vegetable crop, on the same spot, and then worked into the soil; UF/IFAS adds that varieties differ and some are susceptible. Clemson HGIC names French marigolds 'Tangerine' and 'Single Gold' as resistant, and both sources say intercropping marigolds among vegetables is not effective.
Above-ground insects: weak evidence. Clemson HGIC notes that despite their reputation for repelling pests, marigolds attract some insects themselves, including spider mites, aphids, whiteflies and thrips. Use marigolds for what they demonstrably do: nematode suppression as a cover crop, and flowers that NC State Extension says attract pollinators. The site's companion planting science vs. folklore guide reviews the evidence crop by crop.
Deer. Clemson HGIC and NC State Extension both list marigolds as deer resistant, and University of Minnesota Extension says deer and rabbits tend to avoid their odor. No plant is deer-proof under heavy pressure.
Marigold pests and diseases
| Symptom | Likely cause | What to do |
|---|---|---|
| Gray fuzzy mold on spent blooms, spreading to stems in wet weather | Botrytis blight (gray mold) | Per UC IPM: remove old blossoms and plant debris, space plants for air circulation, and avoid wetting foliage. |
| White powder on leaves, usually late summer | Powdery mildew | Space plants properly and keep foliage dry; see the site's powdery mildew guide. |
| Stippled, silvery leaves with fine webbing underneath in hot, dry weather | Spider mites | Per UC IPM: spray water on leaf undersides, then insecticidal soap or oil if needed; keep plants from drought stress. Avoid insecticides such as some pyrethroids and organophosphates, which kill mite predators. More in spider mites on outdoor plants. |
| Stunted, distorted growth with pale or greenish flowers | Aster yellows (phytoplasma spread by leafhoppers) | Per University of Minnesota Extension there is no cure; remove and destroy the plant. See aster yellows. |
| Wilting with wet soil, yellowing lower leaves | Overwatering or poor drainage, leading to root rot | Improve drainage, water less often, move to a raised bed or pot. |
| Leggy plants, few flowers | Too little sun or too much nitrogen | Relocate to full sun; stop fertilizing. |
| Flowering stalls in July or August | Heat stress, or plants setting seed | Deadhead; shear signets back by one-third (Clemson HGIC). |
Common mistakes
| Mistake | Why it matters | Do this instead |
|---|---|---|
| Mistake | Why it matters | Do this instead |
| Planting before the last frost | Marigolds are killed by frost and sulk in cold soil | Wait until after last frost; direct-sow once soil is about 65°F |
| Crowding plants | Poor air flow invites botrytis and powdery mildew; flowers shrink | Space French 8–10 in, African 12–16 in |
| Rich soil and heavy feeding | Excess nitrogen gives big plants with few blooms | Fertilize at planting only; avoid heavy feeding |
| Evening overhead watering | Botrytis infects after 6+ hours of wetness (UC IPM) | Water at the base in the morning |
| Counting on a few marigolds to stop nematodes | Suppression requires a dense cover crop; intercropping isn't effective | Grow a dense block of a resistant variety at least two months before the crop, then turn it in |
| Planting in part shade | Marigolds need full sun to bloom all season | Give them 6+ hours of direct sun |
Frequently asked
When should I plant marigold seeds?
Per Clemson HGIC, start seeds indoors 4–6 weeks before planting time, or about 8 weeks ahead for slower African types. Sow outdoors or transplant only after the danger of frost has passed; University of Minnesota Extension direct-seeds once soil reaches 65°F.
How long does it take marigold seeds to germinate?
Per Clemson HGIC, marigold seed typically sprouts in 5–7 days; University of Minnesota Extension gives 5–8 days at 70–75°F. Cooler soil slows germination, which is one reason not to sow outdoors too early.
Are marigolds annual or perennial?
The common garden marigolds are annuals that die at the first frost. Plants do not survive winter, though seed saved from open-pollinated types can be sown the next year. The site's marigold annual or perennial page explains the details.
Are marigold flowers edible?
Signet marigold (Tagetes tenuifolia) flowers are the ones grown for eating; Clemson HGIC describes them as edible with a spicy tarragon flavor, and University of Minnesota Extension notes they are used in salads or as a garnish. Only eat flowers you can identify with certainty and that have not been treated with pesticides.
Is calendula the same as marigold?
No. Calendula (Calendula officinalis), often called pot marigold, is a different genus from the Tagetes marigolds in this guide, though both are in the aster family. Clemson HGIC notes pot marigold is not a true marigold and is a cool-season annual, unlike the warm-season Tagetes.
Are marigolds bad for pets?
The ASPCA's toxic and non-toxic plant database has no entry for Tagetes marigolds; its "marigold" listings (pot marigold and garden marigold) are Calendula officinalis, which it lists as non-toxic to dogs and cats. NC State Extension notes French marigold has low-severity poison characteristics: its sap can irritate skin. If a pet eats a plant and shows symptoms, call your veterinarian or the ASPCA Animal Poison Control Center.
Do marigolds keep deer away?
Marigolds themselves are rarely eaten: Clemson HGIC and NC State Extension list them as deer resistant. That does not mean a marigold border reliably protects nearby plants, and hungry deer may still browse them under heavy pressure.
Which marigolds are best for containers?
Compact French and signet marigolds suit pots best; University of Minnesota Extension singles out signets for containers, and Clemson HGIC lists compact French series such as 'Durango', 'Bonanza' (10–12 inches) and 'Hot Pak' (7 inches). Use a free-draining potting mix and water when the top inch is dry. African marigolds need a very large container.
Sources
- How to Grow and Care for Marigolds in South Carolina (HGIC 1168), Clemson Cooperative Extension Home & Garden Information Center
- Marigolds, University of Minnesota Extension
- Tagetes patula, NC State Extension Gardener Plant Toolbox
- Botrytis Blight or Gray Mold, UC Statewide IPM Program
- Marigolds (Tagetes spp.) for Nematode Management (ENY-056/NG045), UF/IFAS Extension
- Spider Mites, UC Statewide IPM Program
- Aster Yellows, University of Minnesota Extension
- Toxic and Non-toxic Plants: Garden Marigold (Calendula officinalis), ASPCA Animal Poison Control