Marsh marigold (Caltha palustris), also known as Caltha cowslip or marsh cup, is not really a marigold at all, but rather a member of the buttercup family (Ranunculaceae). Its growth habit is compact and mounding, the height ranging from 1 to 2 feet tall. The waxy deciduous foliage is rich green and each leaf is heart-shaped, kidney-shaped, or rounded with two lobes. The flowers are 1 1/2-inch yellow blooms that usually appear in April and May. In some regions, flowers may continue into August. Growing from spreading rhizomes, these vibrant perennials spread every spring, attracting the first birds, butterflies, and hummingbirds of the season.
Marsh marigold is a very fast-growing plant that is normally planted from seeds sown in the late fall or early spring. Although the leaves are sometimes cooked for consumption, no part of the plant should be eaten raw. The leaves contain protoanemonin, which is toxic and can cause burning of the throat and other digestive symptoms. Consuming large quantities has been known to cause convulsions.
|Botanical Name||Caltha palustris|
|Common Names||Marsh marigold, yellow marsh marigold, cowslip, caltha cowslip, cowflock, May blob, kingcup|
|Plant Type||Herbaceous perennial|
|Mature Size||1–2 ft. tall, 12 to 18 in. wide|
|Sun Exposure||Full, partial|
|Soil Type||Loamy, moist to wet|
|Hardiness Zones||3–7 (USDA)|
|Native Area||North America (northern temperate regions)|
|Toxicity||Toxic to humans and animals|
Marsh Marigold Care
Marsh marigolds are water-loving plants that are often planted in marshes as well as alongside bodies of water such as streams, and they are often the first pond plants to bloom in early spring. They prefer rich, acidic soil and do better than most water plants in partial shade. They can even thrive in locations where they are sometimes submerged up to 4 or 5 inches deep. Space marsh marigolds 18 to 24 inches apart, as they will gradually spread to form dense colonies.
This perennial will bloom consistently in full sun to full shade, an unusual feature, as most flowering plants for water gardens demand full sun. Establish in a south-facing or west-facing direction for best results.
In zones 6 to 7, these plants will appreciates a spot that has some afternoon shade, as being protected from extremely high temperatures will welcome the plant to bloom into summer and maintain healthy foliage.
Give this plant a rich, moist, or boggy soil that is consistently damp or even fully submerged in water. If planting in a rain garden, situate it near the center of the lowest spot where it gets the most water.
Overall, this plant will prefer slow-draining areas. Adding a glorious yellow aesthetic to the edges of a pond or between the rocks near waterfalls, the marsh marigold is native to marshes, swamps, stream margins, and wet meadows in Newfoundland and Alaska south to Nebraska, Tennessee, and North Carolina. Still, they can survive drought by going dormant and returning the following year.
Temperature and Humidity
Marsh marigold is reliably hardy in USDA zones 3 to 7. Where summers are very hot, or in areas of direct sunlight, the marsh marigold may go dormant after blooming. Expect the foliage to wilt and die, and look forward to the following spring’s show.
As a vigorous wildflower, marsh marigolds don't need much in the way of fertilizer, but in poor soils, you may want to fertilize both before new growth and before the first frost with an all-purpose fertilizer.
Propagating Marsh Marigold
Root division is the easiest way to propagate marsh marigold. Here's how to do it:
- In early spring as the foliage begins to emerge, dig up and divide the root clump. (Wear gloves glove to protect your skin from toxins in this plant.
- Replant the pieces immediately in sunny or partially shady spots with moist or boggy soil.
- Keep the roots watered well until they become established
How to Grow Marsh Marigold From Seed
Collect seeds off the plant towards the end of its bloom period and sow them when they ripen. The seeds often will not germinate and sprout until they have gone through a period of damp/cold stratification for 60 to 90 days. Thus, collected seeds planted in the fall often do not sprout until the following spring. Start store-bought seeds in spring.
It may take about three years for seed-started marsh marigolds to mature and start blooming. It will be well worth the wait for these splendid wildflowers to cheerfully welcome many spring seasons to come.
These hardy wildflowers require no protection against winter cold. As cold fall/winter weather kills back the leaves and stems, they can be cut back to ground level to keep the area tidy—but this is not mandatory.
Common Pests & Plant Diseases
Marsh marigold is quite hardy, and pests don't bother it much. Occasionally, it suffers from fungal diseases like powdery mildew and rust. These can be remedied with fungicides or milk spray.
How to Get Marsh Marigold to Bloom
In suitably moist conditions and a sunny location, marsh marigold typically displays its bright yellow blooms in April and May, making it among the first perennials to bloom. If it does not bloom, there are several possible reasons:
- Soil is too dry. These plants need decidedly wet soil in order to bloom. In drought conditions, they may go dormant but usually return the following year.
- Not enough sun. These plants can do fine in partial shade, but deep shade is likely to retard blooming altogether.
- Too much fertilizer. Marsh marigold does not like to be fed—except when the soil is exceptionally barren when a single feeding early in the spring can be helpful.
Common Problems With Marsh Marigold
As a native North America plant, marsh marigold is not technically considered invasive (that label is reserved for foreign plants), but some growers find that it spreads annoyingly fast when given an ideal location. But considering that these are typically boggy locations where other plants don't grow well, it's usually not a problem when marsh marigold colonizes and takes over a wet area.
Growers are sometimes disappointed when marsh marigold seems to vanish as weather turns hot and dry. But unless the drought is extended over a second season, the plants usually return with full vigor when moisture returns to the colony. Supplemental watering of dry ground can prevent this late-season dormancy.
How long does marsh marigold last?
Marsh marigold spreads by rhizomatous roots and by self-seeding, so once it colonizes an area, you can expect it to thrive for many decades, provided its preferred damp conditions don't change. But extended drought, possibly brought on by climate change, has caused some wild colonies to vanish.
Can I cook and eat marsh marigold?
Yes, but only if well-cooked. The flower buds are sometimes cooked and pickled in vinegar. You can also boil the young leaves, with repeated water changes to eliminate toxins, and eat them as cooked greens. But never eat any parts of the plant raw, as they are toxic in this state.
What is the meaning of the botanical name?
The latin genus name, Caltha, derives from the Greek word for "goblet," and refers to the shape of the flower. The epithet palutris means "marsh-loving."
Why is this plant commonly called "marigold" when it doesn't resemble the common marigold?
The common name probably derives from the use of the plant's use in medieval churches to pay homage to the virgin Mary, as in "Mary's-Gold." The common marigolds (Tagetes spp.) also derived their common name from this same medieval practice.