Marigold

Marigold is a common name for several related plants of the daisy family that typically have orange to yellow flowers. True marigolds are also known as calendulas and include the pot marigolds. Another genus of marigolds is native to tropical and subtropical regions of the Western hemisphere. The African marigold is one member of the genus, which is the native to Mexico. It is an annual herb growing up to about 1 m (3 ft) tall and producing large, globular, golden-yellow or orange flower heads. African marigolds have been bred in both single- and double-flowered varieties. French marigold is a smaller Mexican annual, growing about 45 cm (18 in) tall and producing small yellow and red flower heads. The marsh marigold belongs to the buttercup family. Marigolds are easy to grow, bloom reliably all summer and have few insect and disease problems. They have understandably been a favorite annual in many countries for long years.

Scientific classification

Marigolds belong to the family Asteraceae (or Compositae). True marigolds are classified in the genus Calendula. The African marigold is classified as Tagetes erecta and the French marigold as Tagetes patula. The marsh marigold belongs to the family Ranunculaceae and is classified as Caltha palustris.

Types

Marigold (common), Tagetes
Pot marigold, Calendula
Mexican marigold, Tagetes erecta
Tree marigold, Tithonia diversifolia
Desert marigold, Baileya multiradiata
Corn marigold, Glebionis segetum
Marsh marigold, Caltha palustris

Propagation

Marigolds are grown from seeds. They like full to partial sun. Marigold seeds can be directly sowed into your flower garden, or seeded indoors for transplanting later. We recommend planting Marigolds in pots and containers indoors, then transplanting them outdoors. This allows you to make the proper spacing without the need for thinning seedlings.

Sow Marigold seeds early in the season and cover lightly with soil. Water thoroughly once. They germinate easily and will grow quickly, producing their first of a continual display of blooms by mid-summer.

Transplant Marigold plants into your garden after the last frost date for your area. Spacing depends upon size with miniature varieties spaced four to six inches apart, and Giant varieties one to two feet apart.

How to Grow

Marigold plants like rich, well drained soil, but are very tolerant of average to slightly poor soils. Improving your soil quality will produce much healthier plants and flowers, so add plenty of compost. Add a general purpose fertilizer once a month.

Once your Marigolds are established, they should grow well, even if left unattended. Soil should be moist, but not wet. Water them during dry periods, once or twice per week.

Add mulch around the plants for appearance and to keep weeds down.

Around mid-summer, your plants will begin to produce flowers and will continue to do so up to the first frost. You do not need remove dead flower blooms, except for appearance.

Marigolds are annuals and susceptible to frost. They may survive the first light frost with only a little damage. They will not survive a hard frost or freeze.

Height/Spread

Plant height varies with the cultivar. Marigolds cover a full range of sizes from about 6-inch dwarves to 3 foot-tall plants.

Ornamental Features

Marigold flower color ranges from yellow and gold to orange, red and mahogany. Several striped, bicolor and creamy white cultivars are available. Marigold leaves are finely cut and fernlike. Signet marigolds leaves are much finer than those of other types. Foliage color is a rich dark green and in many cases is scented. In African marigolds, the scent is not pleasant, but some other types are grown for their aromatic fragrance.

Landscape Use

Marigolds are used for color massing, edging, borders, cut flowers and container plantings. Most varieties bloom from early summer until hard frost in late fall. Marigolds require full sun and grow best in well-drained soil with plenty of organic matter. Prepare your flowerbeds by mixing in pine bark or leaf mold to 6 to 10 inches deep. Marigolds can be purchased as transplants or seeded directly in the garden. Start seed for transplants inside four to six weeks before planting out. Most marigolds are hybrids. If you save seed from last year’s plants, they may not be the same as what you grew last year. Plant each plant slightly deeper than it was in the pack. Plant French marigolds 6 to 9 inches apart and African marigolds up to 18 inches apart. Water thoroughly. Keep a close check on water during the first 10 to 12 days. After that, water thoroughly once a week if it has not rained at least an inch that week. Remove the old flowers as they fade for continued bloom. Tall marigolds may require staking to prevent the plants from falling over during storms.

Problems

Insects and diseases seldom bother marigolds. Spider mites can be a problem in hot, dry weather. Aster yellows and fungal stem and root rots are occasional disease problems. Some gardeners plant marigolds in their vegetable gardens to repel harmful insects. Studies have concluded they are not effective in reducing insect damage on vegetable crops. French types may be useful for root-knot nematode control in soil.

Species and Cultivars

African marigolds (Tagetes erecta): These marigolds have large, double flowers from midsummer to frost. Flowers may measure up to 5 inches across. They can grow as tall as 36 inches. African marigolds are excellent bedding plants. Tall varieties can be used as background plantings. African marigolds are often called American marigolds. Actually, all marigolds are native to subtropical America, and have been cultivated in Mexico for over 2,000 years. Marigolds cultivars are usually sold as part of a series with similar growth characteristics and a wide range of color.