Gossypium

( goss - EE - pee - um )

At-A-Glance Information

This genus includes species of evergreen shrubs (and some small trees) which need full sun and regular waterings to perform well in the garden. The genus is known for the fiber harvested from its mature seed pods, commonly called Cotton, though there are also more ornamental species that do well in gardens. These plants have a mounding, spreading habit and an almost tropical look to them due to their Hibiscus-like flowers. The blooms will attract pollinators like butterflies and moths to the garden. Take care when planting Gossypium in the landscape, as plant parts are toxic to humans and pets if ingested.

Gossypium Species and Varietals

The genus Gossypium includes 50 species of flowering plants and is a member of the Mallow family (Malvaceae). Growing zones for Gossypium are USDA hardiness zones 8-11. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Gossypium anomalum (Cienfuegosia anomala, Hibiscus anomalus) (Anomalous Cotton, Green Cotton, African Cotton, Pink Wild Cotton)
Native to dry regions of Africa, this species is a wild relative of cultivated Cotton. It forms a shrub that reaches a mature height of 3-5 feet tall with a 2-3 foot spread. It is very drought-resistant. It produces solitary, small reddish-pink flowers with dark centers.

Gossypium arboreum (Tree Cotton, Mpamba Mwitu, Kattuparuthi, Muripparuthi, 亚洲棉, Coton Arborescent)
Native to India and Sri Lanka, this species reaches up to 6 feet tall and produces purplish branches covered with fine hairs. Leaves are green. Flowers produced by this species are pale yellow to white with dark maroon centers. Variety 'Phuti Karpas' was once highly valued for its high tensile-strength cotton, and 'Red' produces reddish-pink flowers.

Gossypium barbadense (Sea Island Cotton, Pima Cotton, Egyptian Cotton, Extra-Long Staple Cotton, ELS Cotton)
This species of Cotton is native to a region that spans from Columbia to Peru, and forms a bush or small tree. They can reach up to between 3 and 10 feet tall when mature, and produce yellow flowers with deep red centers. This species constitutes the source of a small percentage of the overall modern Cotton market, and the major source for longer grades of Cotton. This species is considered invasive in Hawai'i, Niue, Guam, and Fiji.

Gossypium harknessii (San Marcos Hibiscus)
Grows best in USDA hardiness zones 9a-11 or Sunset growing zones 12-24, native to Baja California and Mexico. Gets to 3-5 feet tall and 4-6 feet wide. Stems are red and thick, with lobed green leaves. Lemon-yellow flowers appear in spring, followed by small fruits that split open to reveal seeds and dense white fibers. This shrub thrives in poor soil with moderate irrigation. A very salt-tolerant shrub. Can take heat but leaves can turn yellow in intense, reflected heat.

Gossypium herbaceum (Levant Cotton)
This species of Cotton is native to semi-arid regions of southern Africa and an area that ranges from Syria to Afghanistan. Individual plants typically reach between 2 and 6 feet tall when mature. Leaves are green and palmate. Flowers are yellow to whitish with red centers. Cultivar 'Nigra' produces very dark purple (almost black) foliage and deep pink blooms.

Gossypium hirsutum (Upland Cotton, Mexican Cotton)
This species represents the most widely grown in the genus; it constitutes about 95% of all United States Cotton production exports. Varieties have been bred to produce long and short Cotton fiber lengths. The species forms a shrubby plant that can reach up to between 1.5 and 6.5 feet tall when mature (some varieties can reach up to 13 feet tall). It is a perennial plant that is often cultivated as an annual.

Gossypium sturtianum (Sturt's Desert Rose, Darling River Rose, Cotton Rosebush, Australian Cotton)
These plants reach up to 6.5 feet tall and just as wide, producing pink to dark purple or maroon flowers. Foliage is green. This species is the floral emblem of the Northern Territory of Australia, and is featured on its flag. It is native to arid and semi-arid regions of mainland Australia.

Gossypium thurberi (Arizona Wild Cotton, Thurber's Cotton, Desert Cotton, Algodoncillo)
This species is native to the Sonoran Desert in northern Mexico and Arizona (southern United States). It forms a shrub or small tree up to 10 feet tall, and is popular in ornamental desert landscaping. Flowers are creamy white with a reddish-rose base on each petal. They appear from May through June in the plant's native range, and grow well in USDA hardiness zones 8a-10b.

Gossypium tomentosum (Ma'o, Huluhulu, Hawaiian Cotton)
This species is endemic to the Hawaiian Islands and produces a shrub that reaches up to between 1.5 and 5.5 feet when mature. Flowers are light yellow and leaves are greyish green and downy. The flowers can be used to make a yellow dye, but the seed fibers are short and reddish-brown, not suitable for spinning into thread.

Caring for Gossypium

They thrive in poor soils as long as they are well-draining, Water regularly while the plant is establishing itself, then reduce water to a deep watering every 2-4 weeks in the warmer months of the year. Otherwise, these plants are drought-tolerant and can get by on rainwater alone. Prune minimally to keep in bounds and to remove any frost-damaged foliage.

Gossypium shrubs are typically grown from seed, though some more ornamental species can sometimes be found in desert nurseries. Plant the shrub in a space in the landscape that receives full sun; ideally, they appreciate between 6 and 8 hours of sun each day for the best blooms. Provide some late afternoon shade in warmer climates. When these shrubs are grown in lower light, they will not flower as profusely and produce leggy overall growth. These plants do not like cool air or windy conditions, so ensure that they are situated in a somewhat sheltered location. Ensure that soil is well-draining and has a pH of between 5.8 and 6.5 (acidic to neutral). If local soils do not drain well, make sure to amend the planting area with plenty of organic compost and perlite before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these shrubs are considered to be drought-tolerant, able to get by for much of the year on rainwater alone with supplemental waterings during extended periods of dry weather. Withhold waterings during the plant's dormancy in wintertime.

Gossypium shrubs do not need to be fertilized. Prune to remove crossing, damaged, diseased, or dead branches at any time during the active growing period in spring and early summertime. In late winter or early spring, give the shrub an overall trim to encourage a bushier habit to form. Gossypium plants can be trimmed into small, decorative trees by removing the lower branches and forming the top ones into a somewhat rounded shape. Flowers can be deadheaded, but typically will fall from the plant on their own. These are frost-sensitive plants, and will need protection in cold, especially if temperatures drop below 30 degrees Fahrenheit. Gossypium shrubs can last for between 2 and 10 years in the landscape before needing to be replaced. In commercial cultivation, they are grown as annuals. Fertile plants will self-seed prolifically in favorable conditions, providing volunteer seedlings that can be dug up and used to replace fading ones.

Growing Gossypium in Containers
Gossypium plants can be grown in the ground or cultivated in containers. Choose a container that has adequate drainage holes on the bottom and choose a space in the garden that gets full sun. Fill the container with well-draining potting mix amended with plenty of organic material (compost) and some sand. After planting, apply a layer of organic mulch to the top to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Prune to shape and remove dead, damaged, diseased, or crossing branches at any time during the active growing season in spring and early summer. Gossypium plants can be trimmed into small decorative trees by removing the lower branches and forming the top ones into a somewhat rounded shape. Flowers can be deadheaded, but typically will fall from the plant on their own. Water regularly; Gossypium shrubs grown in containers will need more frequent irrigations than their in-ground counterparts. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch.

Propagation

Gossypium 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 Gossypium shrub, follow the instructions below:

Propagating Gossypium by Cutting

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. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
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 6 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.
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.
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 shrub.

Propagating Gossypium by Seed

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. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed pods on these shrubs are woody and have four chambers, that contain seeds that have filaments resembling small cotton balls. Remove them from the plant, and set them aside. Once you've collected all of your seeds, remove the fluffy, cotton-like covering.
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 7-14 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.
Keep the seedling's potting medium moist, but not too moist, 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.