Marigolds are among the most popular annual flowers. Generally, marigolds are capable of self-seeding, meaning they drop mature seeds onto the soil that successfully germinate the following spring without human intervention. The degree of success with this natural process depends on several factors, including the specific variety of marigold planted and the local climate conditions.
The Direct Answer: Self-Seeding Potential
The self-seeding capability of a marigold is highly dependent on its species. Pot marigolds (Calendula officinalis) are perhaps the most reliable self-seeders and often produce abundant volunteer plants. They are prolific in dropping seeds that successfully sprout year after year.
French marigolds (Tagetes patula) also self-seed successfully in many environments. Many popular French marigold cultivars are hybrids, and their self-seeded offspring may revert to the traits of their original parent plants. This means the next generation might display unexpected colors, sizes, or flower shapes compared to the parent plant from which the seeds dropped.
African marigolds (Tagetes erecta) are the least reliable self-seeders, particularly in regions with harsh winters. While they produce seeds, their larger size and later maturity mean they require a longer, warmer growing season for the seeds to fully ripen and drop before the first hard frost. Some modern, highly-bred varieties of marigolds are intentionally sterile and cannot produce viable seed at all.
Mechanics of Natural Reseeding
For a marigold to successfully reseed, the spent flower head must remain on the plant long enough for the seeds inside to reach full maturity. Once the flower dries out, the resulting seeds must drop directly onto bare or lightly covered soil. Heavy layers of mulch or dense ground cover can prevent the seeds from making contact with the soil surface.
The seeds then require a period of cold temperatures to break their dormancy. They must survive the winter months, which is often only possible in areas with mild winters where the soil does not freeze completely. In colder climates, the seeds may germinate prematurely during a warm spell only to be killed by a subsequent deep freeze.
Successful germination occurs in late spring or early summer after the last significant frost, when soil temperatures consistently reach a warm range, around 70–75°F. The seedlings, called “volunteers,” will emerge when the environmental conditions—light, moisture, and temperature—are optimal for their growth.
Managing Volunteer Seedlings
Gardeners can directly influence the number of volunteer marigolds by controlling the timing of the seed drop. To encourage self-seeding, cease deadheading the flowers in late summer or early fall, allowing the blooms to dry fully and deposit their seeds naturally. A light raking or disturbance of the soil surface in the autumn can help incorporate the dropped seeds slightly below the surface, offering protection over winter.
If the goal is to prevent self-seeding and maintain a tidy garden, consistent deadheading is the most effective control method. This practice removes the developing seeds before they have a chance to mature and fall onto the ground. Any volunteer seedlings that emerge in the spring can be easily pulled or transplanted to a more desirable location.
Volunteer marigolds, especially those resulting from hybrid parent plants, may not replicate the exact color or size of the previous season’s display. Accepting this genetic variability is part of relying on natural reseeding. The resulting plants often revert to a more basic, wild-type flower form.