How to Plant Marigold Seeds: Indoors or Direct Sow

By the Garden Voila editorial team · Updated October 30, 2026 · How we verify

Marigolds are among the easiest flowers to grow from seed. They germinate in days, tolerate heat and poor soil, and bloom in shades of gold, orange and red from early summer until frost. They are also a favorite edging plant for vegetable gardens. This guide covers when and how to plant marigold seeds, both indoors and directly outdoors.

Which marigold are you growing?

Pot marigold (Calendula) is a different plant that prefers cool weather and can be sown earlier in spring and again in fall.

When to plant marigold seeds

• Indoors: sow six to eight weeks before your last spring frost. This is especially useful for tall African marigolds, which take longer to bloom.
• Outdoors: sow directly once the danger of frost has passed and the soil has warmed to about 65°F. French and signet marigolds do very well direct-sown.
• Repeat sowings in early summer keep fresh plants coming for fall.

Use the seed starting calculator to work out the indoor sowing date from your frost date.

How to plant marigold seeds indoors

1. Fill cells or small pots with moist seed-starting mix.
2. Sow one or two seeds per cell, about 1/4 inch deep. Marigold seeds are long and thin; lay them flat and cover lightly.
3. Keep them warm, around 70 to 75°F. Seedlings appear in about five to seven days.
4. Move them under bright light as soon as they sprout to prevent leggy seedlings.
5. Thin to one seedling per cell, and harden off for a week before planting out after the last frost.

How to plant marigold seeds outdoors

1. Choose a spot in full sun. Marigolds tolerate average to poor soil but need good drainage.
2. Loosen the soil and rake it smooth. Heavy fertilizer is unnecessary and leads to leaves rather than flowers.
3. Sow seeds 1/4 inch deep, about 1 to 2 inches apart.
4. Water gently and keep moist until seedlings appear.
5. Thin to final spacing: 6 to 9 inches for French and signet marigolds, 12 to 18 inches for African types.

Caring for marigolds

• Water at the base when the top inch of soil is dry. Established marigolds tolerate some drought.
• Pinch young plants once to make them bushier.
• Deadhead spent flowers to keep them blooming.
• Watch for pests: spider mites in hot, dry weather and slugs on young seedlings. See how to get rid of spider mites.

Marigolds in the vegetable garden

Marigolds are a classic companion plant. Their flowers attract hoverflies and other beneficial insects that eat aphids, and French marigolds can suppress root-knot nematodes, but only when grown densely for a full season and turned into the soil, not as a few plants dotted among tomatoes. Our guide to companion planting: what actually works explains the research.

Saving marigold seeds

Let a few flower heads dry on the plant until they are brown and papery. Pull the dried heads apart; the seeds are the long, black-and-white slivers inside. Dry them for a week and store them in a paper envelope. Seed from hybrid varieties may not come true.

Marigolds pair well with other easy annuals such as zinnias, and our guide to planting seeds covers general sowing technique.

Common marigold problems

• Spider mites: fine stippling and webbing in hot, dry weather. Hose plants off and treat with insecticidal soap. See how to get rid of spider mites.
• Slugs: chew seedlings overnight. Use slug traps or iron phosphate bait.
• Botrytis (gray mold): brown, fuzzy flowers in wet weather. Deadhead and improve airflow.
• Few flowers: too much shade or nitrogen. Move to full sun and stop fertilizing.

From seed to bloom: a marigold timeline

Because African types take much longer, start them indoors in your area so they flower by midsummer, while French marigolds can simply be sown outdoors after the last frost.

Growing marigolds in containers

French and signet marigolds are easy container plants. Use a pot with drainage, a quality potting mix and full sun. One plant fits a 6 inch pot, and three fit a 12 inch pot. Water when the top inch is dry, and go easy on fertilizer: a light feeding once a month is plenty, since rich feeding produces leaves at the expense of flowers. Pinch young plants once to make them bushier, and snip off faded blooms every few days to keep new buds coming.

Are marigolds safe for pets?

The ASPCA lists the common marigold (Tagetes) as mildly toxic to cats and dogs. Chewing the leaves or flowers can cause mild stomach upset, and the sap can irritate skin. Serious poisoning is unlikely, but keep pets that like to nibble away from the plants. Pot marigold (Calendula) is a different plant and is listed as non-toxic. See which flowers are toxic to cats for safer choices.

The three marigold types and how big they get

Garden marigolds are mostly one of three types, and the type decides spacing, height and timing. The University of Minnesota Extension describes French marigolds (Tagetes patula) as 6 to 12 inches tall with single or double flowers up to 2 inches wide, African marigolds (Tagetes erecta) as 3 to 4 feet tall with large double flowers up to 5 inches across, and Signet marigolds (Tagetes tenuifolia) as 6 inches tall or less with single-row petals about 1 inch wide. Penn State Extension gives a slightly wider range for French types, 6 to 24 inches, and says Signet rarely exceed 12 inches. It also points out that African marigolds, despite the name, are not from Africa; the University of Minnesota says the genus is native to Central America and Mexico. Penn State notes French types tolerate rainy weather better than other types, while African types tolerate drought-like conditions and Signets suit hot, dry areas and edging.

Indoor sowing: temperatures and a timeline

University of Minnesota Extension recommends starting marigold seed indoors about 10 weeks before the outdoor planting date, in seed-starting mix, planted about a quarter inch (6 mm) deep and covered fully. Keep the mix moist, using a plastic cover and misting, and expect germination in 5 to 8 days at 70 to 75 degrees F (21 to 24 C). After germination the same source suggests 65 to 75 degrees F (18 to 24 C) by day and 65 to 70 degrees F (18 to 21 C) at night. Penn State also says that starting seeds indoors and transplanting gives earlier flowers, and that seed sown in warm soil sprouts within about a week, with flowers typically about two months later. Use our frost dates tool to find the planting-out date and count 10 weeks back.

Direct sowing outdoors

Minnesota advises direct seeding when the soil reaches 65 degrees F (18 C) and planting larger transplants after frost danger has passed. Penn State says French and Signet types can be planted from spring through midsummer, while African types should go in right after the last frost because they mature more slowly. It recommends sowing about 1 inch apart and a quarter inch deep, then thinning the seedlings. This gives you a simple approach: sow French and Signet in repeated waves for fresh color, and give African types an early start.

Spacing

Spacing differs between the two sources, which is a reminder that these are guides rather than rules. Penn State recommends 8 to 10 inches (20 to 25 cm) apart for French and Signet types and 12 inches (30 cm) for African types. Minnesota suggests planting French and Signet close together to form a hedge, and spacing African types at least 1 foot apart. Try our plant spacing calculator to work out how many plants fill a bed. Tall African types also need staking, according to Minnesota.

Light, soil and water

Minnesota is blunt on light: marigolds need full sun all day to bloom all season long, and blooms continue until frost. Penn State agrees on full sun and adds that plants handle very hot summers, grow in most soils but do best in moderately fertile, well-drained soil, and suit USDA Hardiness Zones 3 through 11 (our growing zone finder can tell you yours). Minnesota gives an ideal pH of 6 to 7 and suggests adding compost or sand to heavy soil to improve drainage. On water, Minnesota says marigolds tolerate drought better than overly wet conditions, and Penn State suggests letting soil dry slightly between waterings, then watering thoroughly and deeply, more often in hot weather.

Feeding: less is more

Marigolds are low feeders. Minnesota recommends working a general-purpose fertilizer with equal nitrogen, phosphorus and potassium into the soil at planting and then none after planting, noting that excess fertilizer reduces blooms by shifting energy to foliage. Penn State likewise warns against high-nitrogen fertilizers and suggests a balanced fertilizer or one with a higher middle number. For containers, Penn State advises a soilless mix with slow-release fertilizer or diluted liquid fertilizer and no overcrowding.

Pinching and deadheading

Both sources recommend pinching the tips of young plants for a bushier habit. Minnesota calls deadheading not required but beneficial: removing spent blooms encourages more flowers, prevents seed set and, because blooms rot easily in humidity, keeps plants looking fresh. Penn State adds that deadheading attracts butterflies and pollinators. Minnesota also advises removing rotting flowers and keeping the soil surface clean to reduce disease.

Pests, diseases and the nematode claim

Penn State says marigolds have few pests but spider mites and aphids can infest them, and that insecticidal soap used per label directions usually solves the problem. Powdery mildew can develop in wet or humid conditions, so water at the base of the plant, keep weeds down and plant in well-drained soil; shade and cool, moist sites lead to poor blooming and more mildew. Minnesota notes the foliage has an odor that deer and rabbits tend to avoid.

The most repeated marigold claim is that they protect other plants from nematodes. Penn State is careful here. It says marigolds can serve as a cover crop to reduce certain nematodes and that some French and African varieties have root chemicals that may suppress root-knot nematode populations, but the method is to grow a thick stand for several months and then till, disk or dig the plants in. It states plainly that interplanting marigolds with other crops does not affect root-knot nematode populations. So a few marigolds beside your tomatoes are for color and pollinators, not nematode control.

Edible or not?

This is a point of confusion. Penn State says Calendula officinalis (pot or English marigold) is edible and used in salads, but flowers of Tagetes marigolds are generally considered inedible, and it advises caution. Minnesota, however, describes Signet marigold flowers as edible. Because the sources disagree, do not eat any marigold unless you are certain of the species and variety, it was grown without pesticides and it is sold for food. Penn State also notes that historical medicinal uses are history and gives no modern evidence for them.

Sources and further reading

• Starting Seeds Indoors, Clemson Cooperative Extension
• USDA Plant Hardiness Zone Map, USDA Agricultural Research Service

Frequently asked questions

Reviewed October 2026. Sources: University of Minnesota Extension, marigolds, Penn State Extension, marigolds from folklore to the home garden