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Fixing Distressed Plants
Marigolds, a staple bloom of Mexican and Indian cultures, can grow anywhere from 5 inches to 4 feet tall, depending on the species you pick. A plant first cultivated by the Aztecs, these blossoms are regularly woven into festivals, like Mexico's Day of the Dead and India's Dussehra and Diwali. And for iterations rich in orange and yellow carotenoids, marigolds provide a natural alternative to fabric dye and food coloring.
As members of the Asteraceae family, these carnation- and daisy-like blooms can self-seed, which make them appear as perennials; most varieties, however, are annuals that grow well in most zones, from 2 through 11. "Marigolds are a great way to add bright, russet hues to the garden," says says Eric Groft, the CEO and Director of OvS, a group of landscape architects, horticulturalists, and designers, and the author of gardening book Beyond Bold.
They aren't, however, just beautiful—they have a utilitarian use in your green space, too: "These species have traditionally been planted alongside vegetables because they attract pests such as aphids, some types of beetles, and spider mites that could impact vegetable production," Groft says.
How to Plant Marigolds
You can plant marigold seeds indoors, about six to eight weeks before your last frost date. To start, sow seeds on the "surface of a tray or small pot filled with ordinary commercial potting soil that is lightly dampened," says Groft. Cover the seeds with a thin layer of vermiculite and then cover the whole tray or pot with plastic, he adds.
Marigold seeds do not need sunlight at this stage; simply setting your container in a warm area will make them to sprout within four to five days after planting. Then, you can "remove the plastic and move the container to a location that gets four or five hours of light each day," Groft says, advising to "keep the potting mix moist but not sopping," which prevents damping-off fungus. When your seedlings start showing new leaves, it's time to transplant your blooms outdoors.
As Mature Plants from a Garden Center
When working with mature plants, prepare a bed for your marigolds in a sunny, clean site in your garden (where water can drain quickly) at least two weeks before planting. The night before you put your marigolds in the ground, run water through them so it drains freely through every container base, hydrating each plant's foliage, stems, and root system.
Next, dig holes at least 8 to 10 inches apart (this guideline may vary based on your species) and remove your marigolds from their containers and untangle their roots. Place each marigold into your planting hole and fill each crevice with soil until it reaches the base of its stem. Press the soil with your hands firmly, forming an even surface on top. Lastly, water to a 4-inch depth. Once established, your marigolds will multiply, even if you leave them unattended.
How to Grow Marigolds
For an abundance of blossoms, it's best to plant your marigolds in full sun. Lowlight conditions will cause the plants to flower in smaller quantities.
To further nourish your marigolds, water them regularly, especially when they are young. Groft cautions to never leave marigolds in dry soil for more than a few days. During periods of extreme heat, it's best to water new plants daily. However, once established, "marigolds will be more drought-tolerant, but will still bloom best if watered weekly," he says.
"Marigolds do not need supplemental fertilizer unless your soil is extremely poor," says Groft. But, if you want to boost nutrition and support better drainage, you can always work in a layer of compost. Ultimately, the best way to maintain marigolds is by deadheading them regularly.
How to Care for Marigolds
Groft notes that pruning away early flower buds will cause a marigold plant to bush out, resulting in a lusher main blooming season. Deadheading, or removing spent flowerheads after they bloom, will also keep the plant producing new flowers well into the fall season.
Marigolds make for stunning outdoor container plants, due to their long-lasting color and texture. Plus, they respond well to transplanting and quickly establish new roots in soil. You can "use ordinary commercial potting soil in any kind of container, but clay pots are especially good," says Groft. "No repotting is necessary, as you'll be discarding the plant when the growing season concludes."
The Most Common Marigold Varieties
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Tagetes erecta (African marigolds)
Commonly used as a bedding or container plant, African marigolds are characterized by their bright-yellow, pom-pom flowerheads, which can become quite large. This variety begin to bloom in early summer; with proper deadheading, they will continue to blossom well into fall. One of the taller marigold varieties, mature plants can reach 3 feet.
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Tagetes patula (French marigolds)
This species is shorter, reaching one foot in height at peak maturity; French marigolds prefer to spread horizontally, resulting in low, but more expansive ground cover. Their ruffled petals range from yellow and orange to brilliant red and russet. On the whole, this variety can withstand wetter conditions.
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Tagetes tenuifolia (Signet marigolds)
While African and French marigolds are bushy and ruffled, Signet iterations are simpler, boasting just five heart-shaped leaves arranged around a sun-burst center. Drought-tolerant and hardy, these blooms are deer- and rabbit-resistant—which is why they are commonly used to line fruit and vegetable gardens.
How to Identify and Treat Disease in Marigolds
Like most plants, marigolds are not immune to rots, blights, and mildews, including Powdery mildew, a fungal disease. A telltale sign that your marigold is experiencing this ailment? If leaves splash up from the ground with white residue, fungal spores are growing, notes Groft. But there is good news: Although it may take away from the plant's beauty, Powdery mildew is seldom fatal.
Still, for the best disease prevention, continuously provide your marigolds with proper air circulation by ensuring there is amble room between plants. Watering them by "ground-soaking, rather than by overhead spraying," says Groft, should also help.
How to Identify and Fix Signs of Distress in Marigolds
Remember that most signs of marigold distress—like wilting, decay, or white spots—are caused by fungal spores, which is why air flow and correct watering practices are critical. To mitigate the infection, remove impacted plant materials, which can limit the spread of disease, Groft says. If all else fails, amend your soil with compost; add grit and sand to loosen the earth if you're working with heavy clay soil.
Wilting marigolds may also signal thirst. The best thing to do is assess your plant and water it regularly, sans over-watering. Root rot can also cause wilting, so it's essential to stick to containers that drain well (don't use saucers), or well-draining soil if you're working in a bed.