Marigolds
Marigolds can add an incredible amount of color to the sunny, summer garden. In addition to their value as ornamental plants, marigolds have been prized for medicinal qualities and for their ability to help control nematodes in the garden. They were originally native to Mexico and Central America, but after they spent a couple hundred years across the Atlantic ocean, the same plants came back to us as French and African marigolds.While it doesn't change what the plant actually is, it does make it more confusing when you're looking for marigolds in the seed catalogs or at garden centers.
For some reason, marigolds now have a reputation as being ordinary and are often overlooked when we are selecting annuals and designing our flowerbeds. But that hasn't always been true. Gertrude Jekyll, whose innovative use of color in garden design changed the face of gardening in England, incorporated drifts of marigolds in many of her designs. Rosalind Creasy, famous for her books on edible landscaping, became a marigold convert after using them extensively to rid her garden of nematodes. Marigolds offer a huge variety of plant heights, flower forms and colors; it is hard to make any general statements that describe them as a group except to say that they all bloom (though some more prolifically than others).
Many marigold varieties are strong in the orange and yellow color range, but they also include some incredible maroons, reds and even creamy whites. Plant height can vary from 6 inches to 3 feet and flowers will range from tiny, half-inch singles to huge, 4-5 inch doubles. The one factor they all have in common is a fragrance that is so distinctive that one of the plant's common names is "Stinking Roger." While the fragrance may vary slightly, it is stronger than in most plants because it is exuded from the flowers, leaves, stems and roots. The fragrance may be what makes marigolds effective in repelling nematodes in the soil.
When selecting marigolds for the garden, be sure to take into consideration that some of the African/American varieties are not day neutral and they won't bloom well until mid-summer when the days begin getting shorter.
How to Grow Marigolds
As long as you can provide lots of sun and well-drained soil, you can grow marigolds. To bloom well, they need at least 6 hours of direct sun each day. With less sun, the blooms will be sparse. If the soil isn't well drained, be sure to incorporate lots of coarse organic matter to improve the drainage. Marigolds don't require much fertilizer so feed them every few weeks with a water-soluble, such as Bachman's Mighty Bloom™. If you want to use dry organic fertilizer, a single application early in the growing season will be enough. Marigolds can be attractive to slugs and spider mites. If you experience problems with either of these pests, check our information sheets on those subjects for specific control suggestions. Some varieties with extremely large double flowers can have problems with botrytis ruining the blooms during humid weather.
Almost all marigolds will need to be deadheaded during the growing season. Deadheading is removing the fading flower heads before they go to seed. By deadheading, you divert the plant's energy from setting seed to producing more flowers. If you want to avoid deadheading, try growing Signet marigolds. Their blooms are small and fresh blooms quickly cover the fading flowers. If you want to avoid marigolds self-seeding into your garden, try growing the triploid varieties. They don't set viable seeds.
Types of Marigolds
African (or American) Marigolds Tagetes erecta
African marigolds are the largest plants and they have the largest flowers and leaves. Blooms are always semi or fully double (similar in form to a carnation). Typically the flowers are 3-4 inches across and in solid colors, usually shades of orange or yellow. Plants range from bold 24-30 inch tall background plants to dwarf 9-inch tall border plants. All African marigolds are day length sensitive except for the Discovery series, which will bloom earlier in the growing season.
Tall Variety
Jubilee (32")
Medium Variety
Antigua (12-16")
French Marigolds Tagetes patula
French marigolds are smaller, bushier plants with smaller flowers that average 2 inches across. Bloom types can be either single (a single row of petals around a center), anemone (a single row of overlapping petals around a center), carnation (fully double with lots of rows of petals around a center) or crested (where the center on a double flower is hidden by dozens of short petals). French marigolds will bloom from early summer through fall and because their blooms are smaller, they aren't as affected by bad weather. The color range on French marigolds is much broader than the yellow, orange and gold of African marigolds. French marigolds also come in rich reds, mahogany and bi-colors.
Notable Varieties
Disco, Bonanza, Boy, Safari and Aurora
Signet Marigolds Tagetes tenuifolia
Signet marigolds bloom prolifically with very small flowers on compact, mounded plants with ferny foliage. The blooms are about the size of a dime with a single row of petals around a yellow center. Flowers can be yellow, orange, gold, mahogany or bi-colored. Signet marigolds are often sold along with herbs as a companion plant for nematode control, edible flowers (with a mild tarragon flavor) and their subtle lemony fragrance. While signet marigolds don't need deadheading, it helps to cut the whole plant back an inch or two when the weather gets hot. The plant will fill back out as the weather cools.
Notable Varieties
Lemon Gem, Orange Gem, Red Gem and Tangerine Gem
Triploid Marigolds Tagetes erecta x patula
Triploids, a cross between African and French marigolds, are valued because they bloom earlier, the flowers are a little larger and offer more substance and the plants do not set seed, no matter how stressful the growing conditions. The most notable triploid marigolds are the Zenith and Nugget series that can be found in seed catalogs. Zenith's flowers are an interesting combination of crested and anemone types.
Tagetes lucida
Known also as either sweet mace, Mexican marigold, Mexican tarragon or Spanish tarragon, this 16-24 inch plant has anise-scented and flavored foliage and flowers. The orange-gold single flowers appear in mid to late summer. Even though it is an attractive plant, it is grown primarily for its herbal value since it doesn't bloom all season like other marigolds.
Additional Bachman's Information
Fertilizing Annuals and Perennials
All About Watering
Ugh! Slugs!
Aphids, Whiteflies and Spider Mites
Commonly Uses Annuals
Underused Annuals
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