Gossypium tomentosum aka Hawaiian Cotton

Gossypium tomentosum is a shrub called Hawaiian cotton or Ma'o. It is part of the mallow family, Malvaceae. It grows wild in the Hawaiian Islands. It is endemic there: its natural range is nowhere else. Kew places it in a tropical climate with dry seasons. This fits its use in warm, dry gardens.

Hawaiian cotton sheds its leaves and has a spreading form. Garden plants grow about 6 feet [1.83 metres] tall. They can spread about 10 feet [3.05 metres] wide. Leave room for this width when you choose a site. Without pruning, it can grow beyond a neat shrub shape. Prune it to keep its shape compact and curb sprawling growth. Its leaves add colour to the garden. The sources give no more facts about leaf shape or bark.

The bright yellow flowers stand out in the garden. Missouri Botanical Garden says it blooms in season. It does not name the months when flowers appear. The same source lists the fruit as showy, too. Both the blooms and fruit add to its garden value. In Hawaii, gardeners use this shrub as an accent plant. They also grow it to form a hedge. Close trims let them use it as low ground cover. It copes with drought, so it suits gardens that save water.

Grow Hawaiian cotton in full sun and rich, fertile soil. The soil should hold some moisture but still drain well. Do not plant it where the ground stays wet. Missouri Botanical Garden lists its water needs as moderate. Plants can cope with drought once they are established. This does not mean that they need dry soil. Its listed hardiness range is USDA zones 10–12. Frost harms this tender shrub, so keep it free from frost. It needs a moderate level of care. This includes pruning and checks on moisture in the soil.

Pests can harm plants grown in Hawaii. Some insects chew the plant; others feed on its sap. Scale insects, mealybugs and nematodes may cause problems. Watch for spider mites as well. Diseases may include rots, leaf spot and wilts. These risks make good drainage and routine checks worth care. The supplied species evidence does not confirm any edible parts. Nor does it confirm any food uses. It gives no firm basis to rate toxicity, either.