Tagetes tenuifolia aka Signet Marigold

Tagetes tenuifolia thrives in warm temperatures and is frost-tender. Seeds germinate best at 70-75°F (21-24°C), with seedlings emerging in about one week under these conditions. Plant outdoors only after all danger of frost has passed. The plant performs well during hot summers but blooming may temporarily decrease during extreme heat, resuming when temperatures moderate. As an annual, it will die with the first fall frost.

Tagetes tenuifolia is prized for its exceptionally aromatic foliage, which releases a distinctive lemon verbena-like scent when bruised. The fragrance is notably stronger and more pleasant than most other marigold species. The citrus-anise aroma can persist for up to an hour after handling the leaves. This intense fragrance makes it popular for sensory gardens and explains its common name 'Lemon Marigold'.

Tagetes tenuifolia produces abundant small, single flowers about 1 inch across, significantly smaller than African or French marigolds. Each flower head typically has 5 ray florets and 7-9 disc florets. Flowers come in yellow, orange, red/burgundy, and bicolored varieties. The plant is a prolific bloomer, with flowers generously covering the fine, lacy foliage from early summer until frost. Deadheading spent blooms encourages continuous flowering throughout the season.

The Gem series is the most popular commercially available group of signet marigolds, featuring compact dwarf plants. 'Lemon Gem' produces bright yellow flowers with a pronounced citrus flavor. 'Tangerine Gem' has orange flowers said to taste faintly of orange. 'Orange Gem' features bright orange blooms. 'Red Gem' offers crimson flowers with a peppery, citrus-like flavor. 'Golden Gem' and 'Starfire' (with colors ranging from light yellow to red-brown) are also widely available.

Tagetes tenuifolia is primarily an outdoor plant and performs best in garden beds, borders, and containers in full sun. It grows in USDA zones 2-11 as a warm-season annual, planted after the last frost. The plant requires at least 6 hours of direct sunlight daily and cannot tolerate shade.

Pinch seedlings when they reach about 4 inches tall to encourage bushier, more compact growth. Regular deadheading of spent flowers promotes continuous blooming throughout the season. As flowers die, they tend to hang on the plant and detract from its appearance, so prompt removal keeps plants looking tidy. Light shearing can stimulate new waves of bloom if flowering decreases during summer heat.

Tagetes tenuifolia is easily grown from seed. Start seeds indoors 6-8 weeks before the last spring frost date, or sow directly outdoors after all danger of frost has passed. Seeds germinate quickly, often within one week at temperatures of 70-75°F (21-24°C). Cover seeds only lightly with soil. Plants typically reach blooming stage in 45-50 days from germination.

Spider mites are the most common pest, especially during hot weather. Other potential pests include whiteflies, leafhoppers, slugs, snails, and leafminers. UF IFAS rates pest resistance as 'very sensitive' in Florida conditions. Disease issues include Botrytis blight (gray mold), wilt diseases, leaf spot fungus, and Phytophthora. Predatory mites and wasps can be used for biological pest control. The plant is notably deer and rabbit resistant.

Tagetes tenuifolia is insect-pollinated, with flowers that attract bees, butterflies, and various beneficial insects. The abundant small flowers provide excellent nectar and pollen sources throughout the growing season. This makes it valuable for pollinator gardens and biodiversity. The plant is commonly used in butterfly gardens and as a companion plant where its flowers support beneficial insect populations.

Yes, both the flowers and leaves of Tagetes tenuifolia are edible with a pleasant citrus-like flavor, earning it an edibility rating of 2 out of 5 from PFAF. The petals have floral notes with hints of citrus, anise, and mild spice. Use flowers to garnish salads, desserts, and beverages, or incorporate into egg and rice dishes. Remove the white or pale green heel at the petal base which can taste bitter. The aromatic leaves work as flavorful salad greens and make excellent microgreens. Always ensure plants have not been treated with pesticides before consuming.

Beyond ornamental and culinary uses, Tagetes tenuifolia has valuable pest management properties. It also deters asparagus beetles and bean weevils. The flowers produce a yellow dye. It functions as a dynamic accumulator in garden ecosystems.

If you're looking for a plant that offers a moderate level of challenge, Signet Marigold is a great choice to test your gardening skills.

New growth will sprout from the top of the Signet Marigold as it grows vertically.

Signet Marigold’s native range is the Americas.

Signet Marigold should be watered regularly, allowing the soil to dry out between waterings.

Signet Marigold loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

Signet Marigold requires abundant, bright, and direct light to thrive. The best placement for this plant is within one foot of a window to ensure it receives enough light. If you live in an area with more extreme weather, such as hot summers or cold winters, you may need to adjust the placement of the plant accordingly. During hot summer months, it is important to place the plant away from full sun, as this can cause the leaves to yellow or burn. During cold winter months, it is best to move the plant closer to the window to take advantage of the extra light that can help it survive. By keeping an eye on the current weather in your area, you can make sure your Lemon Marigold is always in the right place to thrive.

The Signet Marigold does not need extra humidity. Plants primarily absorb water through their root system, making soil watering the best way to provide humidity to your plants.

The Signet Marigold should be repotted when it has doubled in size or annually, whichever comes first. Providing fresh potting soil with all the essential nutrients each year ensures the plant's well-being, eliminating the need for fertilizer. Remember, plants derive their energy from the sun and not fertilizer.

Signet Marigold is poisonous if ingested. We suggest keeping this plant out of reach if you have children, cats, or dogs in the home.

During the cold period, it is common for Signet Marigold to go dormant, resulting in a slowdown of growth. To accommodate this, waterings should be spaced out more.