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Plant Answer Line Question

Keywords: Plant care, Coleus, Medicinal plants

I want to know about Coleus forskohlii a plant of South Africa. What growing conditions does it need, and what are its medicinal properties?


The plant you ask about is Coleus forskohlii (also known as Plectranthus forskohlii) in the family of plants called Lamiaceae. If your growing conditions resemble those of its native range (it grows wild in parts of West Bengal), you may be able to grow this plant.

The article referenced below, entitled "Development of Coleus forskohlii as a medicinal crop", from the Food and Agriculture Organization Document Repository, should give you much information of interest. The document may be found in the online FAO Corporate Document Repository.

Here is an excerpt from the above web document:
Coleus forskohlii grows wild on sun-exposed arid and semi-arid hill slopes of the Himalayas from Simla eastward to Sikkim and Bhutan, Deccan Plateau, Eastern Ghats, Eastern Plateau and rainshadow regions of the Western Ghats in India. Latitudinal and altitudinal range for the occurrence of the species is between 8 degrees and 31 degrees N and 600-800 m respectively. The species was studied for its ecological preferences in its native habitats throughout its distribution range excluding Eastern Plateau, Sikkim and Bhutan. Before the botanical studies were undertaken, the species was studied in the regional floras and herbarium specimens were examined in seven zonal herbaria of the botanical survey of India at Dehra Dun (Himalayan flora), Allahabad (Central India flora), Shillong (northeastern India flora), Jodhpur (Rajasthan flora), Pune (western India flora), Coimbatore (southern India flora) and Port Blair (Andaman and Nicobar group of islands flora), as well as at the Forest Research Institute, Dehra Dun and the Blatter Herbarium in Bombay. Eleven representative ecogeographic areas were selected for habitat and population studies; between 1982 and 1985, 27 botanical trips were made for the purpose. Coleus-growing areas in the Himalayas in Uttar Pradesh were visited every month from April to December, and the other areas were visited at least twice during the blooming period. The following is the summary of the observations made on different populations and habitats of C. forskohlii (Shah 1989).
C. forskohlii is a subtropical and warm temperate species naturally growing at 600-1800 m elevation
The species grows on sun-exposed hill slopes and plateaus in arid and semi-arid climatic zones
The species inhabits loamy or sandy-loam soil with 6.4 to 7.9 pH
The species is herbaceous with annual stems and perennial rootstock

The medicinal uses of this plant have not been evaluated fully for safety. Sloan-Kettering Cancer Center also has useful information about Coleus forskohlii. Here is a brief excerpt: "Very limited data are available concerning the efficacy of forskolin. Most studies performed with forskolin have been human trials; those performed on heart failure and glaucoma are inconclusive."

As with any drug or herbal medicine, you should consult a medical professional if you have questions about its use.

Date 2018-04-11
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Plant Answer Line Question

Keywords: Plant cuttings, Coleus

I have taken cuttings from my Coleus plants and rooted them in water. They now have about 2 inches of fine roots growing. I'm planning to overwinter them. Should I pot them up in potting soil now?


According to Coleus: Rainbow Foliage for Containers and Gardens by Ray Rogers (Timber Press, 2008), growing Coleus from cuttings (rooting them, as you did, in water) is a fine way to propagate more plants. The cuttings will survive for weeks or even months in nothing but water, and with soluble fertilizer, this time could even be extended.

However, since you want plants which may eventually live somewhere other than the windowsill or counter, Rogers recommends removing the cuttings from the water when roots are an inch or two long, and planting them in growing medium. This is because roots which are produced in water are less sturdy, so making a transition to growing medium helps the plant develop. (Long water roots are easily damaged if pressed too hard when potting them up.) As for the potting medium, even garden soil can be used if it is not heavy clay and does not dry out. Since you are going to keep your plants indoors over winter, you may want to use purchased potting mix which has an open structure (drains well but will not dry out too fast). The mix might include bark, coir, perlite, pumice, or other ingredients. The author has a preference for vermiculite, but be careful to wear a dust mask when handling any fine materials; you definitely don't want to get particles in your lungs.

Once you've potted the cuttings, keep the medium moist but never soggy, and keep them humid (using a mister, for example). Cuttings need bright light but not direct sun, and should be kept at about 70 degrees. If room temperature drops below 50, you may want to set the pots on a heating mat. You don't need to add fertilizer while the cuttings are getting established. You can move the cuttings into larger pots once they've developed a strong root system (at least a week).

Other tidbits of information that may be useful:

  • Cuttings can be taken from any piece of stem on the parent plant, but it's best to choose stems which are neither the youngest nor the oldest growth.
  • Cuttings taken from the sunnier side of the plant have firmer tissue and may root more strongly than cuttings from the shadier side, but they will also need consistent humidity and protection from intense sun while rooting.
  • Cuttings will look like the parent plant if the parent plant is a genetically stable cultivar, but some cultivars (especially with pale pink in the center of their leaves) are more prone to reverting or sporting.
  • Once night temperatures outdoors are above 60 degrees, it should be safe to move your plants outdoors (but it's always a good idea to harden them off gradually beforehand).

Date 2018-04-21
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Garden Tip

Keywords: Athyrium, Foliage plants, Coleus

From knock-your-socks-off colors of Coleus to the dreamy silver elegance of Japanese painted fern (Athyrium niponicum var. pictum), the theme is foliage. Flowers, mostly, are ephemeral. For longer lasting color with less fuss, combine foliage plants in your garden design.

Ornamental Foliage Plants, by Denise Greig (Firefly Books, $45) inspires with a section on foliage plants for specific themes and situations. Judy Glattstein's prose in Consider the Leaf: Foliage in Garden Design, (Timber Press, $24.95) is rich with experience and example, including information about growth habits and care. David Joyce organizes plants by leaf shape and size, texture, color, and overall plant form in Foliage: Dramatic and Subtle Leaves for the Garden (Trafalgar Square Publishing, $35). The highlight of Leaf, Bark and Berry: Gardening with Foliage Plants, by Ethne Clarke, is a plant directory organized by color groups with luscious photos (out of print, but available through online booksellers and at the Miller Library).

On the web, the University of Illinois Extension has an attractive and easy to use Fabulous Foliage website for using plants with colored foliage. Give it a try.

Date: 2007-04-03
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May 31 2018 13:14:08