Coleostephus

( koe - lee - oh -  STEF - us )

At-A-Glance Information

The genus Coleostephus is a member of the plant family Asteraceae, and includes three species, only one of which (Coleostephus myconis, commonly known as Corn Marigold) is commonly cultivated in landscapes. Also sold as Chrysanthemum multicaule, these happy flowering plants need full sun and regular water to perform well. Native to Southern Europe, they grow best in zones A1-A3 and 1-24 (to find your zone, click here: Zone Map). They bloom best in cooler weather, showing off their yellow daisy-like flowers that rise above 6-8 inch tall mats of green foliage. These plants are considered annuals, but will last for about two years in the ground if planted in a mild-winter, cool-summer climate. They also do great in Alaska, where their blooms last from the beginning of summer to the first frost of the year. Varietal 'Moonlight' has lemon yellow flowers. Grow these plants in mixed beds and borders, or in pollinator, native, cottage, or informal landscapes.

Caring for Coleostephus

Coleostephus, or Corn Marigold, is best when grown in full sun. Ideally, these plants should be receiving between 6 and 8 hours of direct sun each day for best performance and flowering. They appreciate soil that is well-draining and moderately fertile with a pH of between 6.0 and 7.5. If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. After planting, mulch around the base with organic mulching material to help retain soil moisture and suppress weed growth. Keep mulch away from the plant stems, as this can encourage an environment for root rot issues to take hold. Fertilizing these plants is not necessary; they can perform well even in poor soils. If plants seem to be struggling, have yellowing foliage, or are not flowering well, they may benefit from a yearly early springtime feeding with a 2-inch layer of compost applied around the planting area. No pruning is needed other than to deadhead for a neater appearance and more blooms. If plants are getting leggy, they can be sheared back by about half to encourage a bushier habit. Water new plants regularly to help them establish a strong root system. At maturity, these plants like to have a slightly moist soil around their root systems.

Propagation

Coleostephus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Corn Marigold, follow the instructions below:

Propagating Coleostephus by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 3-4 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new plant.

Propagating Coleostephus by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 10-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  4. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Problems and Pests

Coleostephus, or Corn Marigold, flowers are typically free of pest and disease issues in the garden. For commonly encountered pests and diseases in the landscape, including how to treat and prevent them, consult the following pages:
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Gallery

Coleostephus seeds.
Coleostephus plants produce yellow daisy-form flowers.
These flowers will attract pollinators to the garden.
Foliage of these plants is green and has serrated edges.
These flowers are typical for Asteraceae genera.

Videos

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Resources

Coleostephus Species, Wild Yellow Daisy
Wikipedia: Coleostephus 
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 256, Coleostephus myconis
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