The sago palm (Cycas revoluta) is a type of gymnosperm known as a cycad that has existed on earth for more than 150 million years. The sago palm is one of the most popular cultivated cycads, enjoyed for its symmetrical habit of dark green, prehistoric-looking leaves and low care requirements. Though sago palms are often grown indoors as houseplants, they make excellent specimen, border and container plants for outdoor spaces where hardy.
A native of southern Japan, sago palm may be grown in U.S. Department of Agriculture plant hardiness zones 8 to 10. Hardiness may be borderline in USDA zone 8, though Floridata claims that established sago palms can survive temperatures as low as 13 degrees Fahrenheit without suffering damage. The plant is tolerant of full sunlight or full shade. In full shade, leaves will grow larger. If growing multiple sago palms, provide at least 5 feet of space between them to accomodate the cycad's large leaves.
Well-draining soil is absolutely crucial to the health of this plant. In compacted soils the palm will probably develop rot. A light, sandy soil enhanced with organic matter is ideal. To help maintain moisture in the soil and suppress competitive weeds, apply a thin layer of bark or leaf mold over the root area. Floridata recommends feeding the palm with a balanced slow release fertilizer or liquid fertilizer diluted with water, in rates recommended on the label. Roots are sensitive and can be damaged by excessive fertilization or by fresh manure.
Water young sago palms regularly throughout the growing season to promote healthy growth, but do not allow the soil to become flooded or water-logged. Once established, the sago palm is quite drought-tolerant. Sago palm can benefit from winter protection, especially in USDA zone 8. Cut back dead leaves and mulch well to help keep the roots warm. Some frost burn is okay, as the plant will produce fresh new leaves in the spring. Sago palm may be propagated by seeds allowed to age for two or three months before they are planted in moist, warm soil. Germination generally takes two or three months.
The seeds, leaves and stem pith are all poisonous to humans, potentially causing vomiting, diarrhea, headache, dizziness and seizures, according to North Carolina State University. Though flour made from the stem pith is technically edible, it is poisonous if not processed correctly. Contact the American Association of Poison Control Centers' free Poison Help Line at 1-800-222-1222 if you have concerns. The ASPCA lists sago palm as toxic to cats, dogs and horses, potentially causing vomiting, liver damage or failure and even death. Contact your veterinarian or the ASPCA Animal Poison Control Center at 888-426-4435. A fee may apply.