Sago Palm (Cycas revoluta)

Cycad, Japanese Sago Palm, King Sago Palm, Sago Palm

The sago palm (Cycas revoluta) is a popular houseplant known for its feathery foliage and ease of care. In fact, this is a great plant for beginners and makes an interesting addition to nearly any room. It can even be grown outdoors. While the name might imply that it is a palm, this plant is actually considered a cycad, one of the oldest groups of plants dating back to prehistoric times — hence the plant’s hardiness.

I. Appearance and Characteristics 

Cycas revoluta (Sotetsu [Japanese ソテツ], sago palm, king sago, sago cycad, Japanese sago palm) is a species of gymnosperm in the family Cycadaceae, native to southern Japan including the Ryukyu Islands.

This very symmetrical plant supports a crown of shiny, dark green leaves on a thick shaggy trunk that is typically about 20 cm (7.9 in) in diameter, sometimes wider. The trunk is very low to subterranean in young plants, but lengthens above ground with age. It can grow into very old specimens with 6–7 m (over 20 feet) of trunk; however, the plant is very slow-growing and requires about 50–100 years to achieve this height. Trunks can branch several times, thus producing multiple heads of leaves.

The leaves are a deep semiglossy green and about 50–150 cm (20–59 in) long when the plants are of a reproductive age. They grow out into a feather-like rosette to 1 m (3.3 ft) in diameter. The crowded, stiff, narrow leaflets are 8–18 cm (3.1–7.1 in) long and have strongly recurved or revolute edges. The basal leaflets become more like spines. The petiole or stems of the sago cycad are 6–10 cm (2.4–3.9 in) long and have small protective barbs.

Roots are called coralloid with an Anabaena symbiosis allowing nitrogen fixation. Tannins-rich cells are found on either side of the algal layer to resist the algal invasion.

As with other cycads, it is dioecious, with the males bearing pollen cones (strobilus) and the females bearing groups of megasporophylls. Pollination can be done naturally by insects or artificially.

Toxicity

Cycad sago is extremely poisonous to animals (including humans) if ingested. Pets are at particular risk, since they seem to find the plant very palatable. Clinical symptoms of ingestion will develop within 12 hours, and may include vomiting, diarrhea, weakness, seizures, and liver failure or hepatotoxicity characterized by icterus, cirrhosis, and ascites. The pet may appear bruised, have nose bleeds (epistaxis), melena (blood in the stool), hematochezia (bloody straining), and hemarthrosis (blood in the joints). The ASPCA Animal Poison Control Center estimates a fatality rate of 50 to 75% when ingestion of the sago palm is involved. If any quantity of the plant is ingested, a poison control center or doctor should be contacted immediately. Effects of ingestion can include permanent internal damage and death.

All parts of the plant are toxic; however, the seeds contain the highest level of the toxin cycasin. Cycasin causes gastrointestinal irritation, and in high enough doses, leads to liver failure. Other toxins include Beta-methylamino L-alanine, a neurotoxic amino acid, and an unidentified toxin which has been observed to cause hindlimb paralysis in cattle.

II. How to Grow and Care

Sunlight

Sago palms prefer bright, indirect light. Avoid placing them in direct sunlight. The scorching afternoon sun can wilt and burn the foliage in the summertime, so some protective partial shade is necessary, yet too much shade can result in sparse leaves and an unhealthy plant. When grown indoors, choose a bright east-, west-, or south-facing window. Indoor plants can be moved outside in warm weather as long as the container is in dappled sunlight.

Temperature and Humidity

These plants love warm, humid conditions. However, sago palm are cold hardy compared to other palms and can briefly tolerate cold temperatures, but frost can damage the foliage, and temperatures below 23 degrees Fahrenheit will likely kill the plant. When grown indoors, protect your sago palm from drafts and airflow from heating and air-conditioning vents; extreme temperature fluctuations can damage the plant.

Watering

Sago palms have some drought tolerance, but they prefer a moderate amount of moisture in the soil. Water whenever the soil feels dry to the touch, making sure never to overwater to the point of soggy soil. Slightly reduce watering in the winter when the plant is not actively growing.

Soil

Sago palms aren’t overly picky about their soil, but they do need good drainage. A sandy soil that’s somewhat rich in organic matter and slightly acidic to neutral soil pH is ideal. For container plants, a potting mix made for cactus or palms is suitable.

Fertilizing

Fertilize monthly throughout the growing season (spring to fall) with a liquid fertilizer, using an 18-8-18 ratio (nitrogen-phosphorus-potassium), mixed according to the package directions. You can also use slow-release fertilizer two to three times during the growing season, following package instructions. To calculate how much fertilizer you need, figure you will need about 1 1/2 pounds of sago palm fertilizer for every 100 square feet of ground. If your sago is planted in clay, a less porous medium, you will need half the amount of fertilizer. It’s best to fertilize right before a rain shower, which helps distribute the plant food.

Planting Instructions

Sago is usually grown indoors but it can be grown as an outdoor palm tree in a pot or the ground under the right conditions. Newly planted sago palms should only be moved during early spring, and mature palms can be transplanted during early spring or late fall.

To plant sago palm outdoors, choose a sunny spot that also has enough partial shade so the leaves won’t scorch. If planting directly in the ground, follow these suggestions:

  • Only repot or transplant new pups in-ground if they have formed extensive root systems.
  • Amend the existing soil around and a few inches below where the plant will sit with compost and a sandy mix to get the necessary drainage a sago palm needs to thrive.
  • Do not plant a sago palm too deep or it will not grow well; plant it the same depth as it was in the nursery container and no lower.
  • If planting pups that were not in a container, make sure the green part is exposed and the bark-like portion is buried in the soil.
  • Water once or twice a week depending on rainfall.

Pruning

Only trim sago palm when the leaves have turned completely brown. Keep yellowing leaves intact. They may not look pretty, but they are still absorbing nutrients for the plant. Removing yellowing leaves may spur further yellowing and worsen the plant’s health. If you must remove some of the fronds, the safest to cut away are those along the bottom circumference of the plant. Using sterilized pruning shears or hand pruners, cut them as close to the trunk as possible.

Propagation

Palm propagation typically occurs by planting seeds. But this process takes longer and is often ineffective. Propagation by division is the quicker and easier way to go. Sago palm develops pups or offsets that look like baby plants that grow in clusters at the base of the plant. Separating the pups from the parent plant alleviates crowding, competition for water, and promotes more air circulation around the plant base. The best time to transplant those pups is early spring or late fall. Here’s how to cultivate the offsets:

  • If you have a sago palm with offsets or baby offshoots, you can divide the plant. You will need a hand trowel, knife, or scissors; a container; and well-draining soil suitable for palm trees. Sterilize the tools with an alcohol- or bleach-based solution before use.
  • Some offsets are loosely attached and are easily removed with a tug, or you might need to use your scissors, a knife, or a hand trowel to pry or cut off the offset.
  • Place the offset on a tray for a few days in a shady spot to allow the cut to dry and callus over. The callus helps keep diseases away from the plant.
  • Fill a pot partially with well-draining soil. The pot should only be about 2 inches larger than the circumference of the offset, and the pot should have about two inches of growing room at the bottom too. Center the offshoot in the pot and fill in the sides with potting soil. Water thoroughly.
  • Place the plant in a sunny location indoors or a shady spot outside. It should take a couple of months for rooting to occur. Allow the plant to dry out between waterings.

Sago palm can grow from seeds, which are either male or female. It doesn’t matter which one you have; either will grow into a plant as long as the seeds come from a reputable source. Sago palm seeds are bright red to orange-hued. The seeds contain toxins, so wear gloves when handling them.

  • To prepare the seeds, soak them in room temperature water to soften them and remove the outer husk.
  • Plant them in a shallow seed starting tray or pot.
  • Cover the seeds with a sand-based seed starting mix and place them in a warm spot.
  • Keep the soil moist as you wait for the seedling to emerge.
  • Like many large seeds, be prepared to wait patiently. Sago palm seed germination can take several months.

Potting and Repotting 

Sago palms are good container plants indoors or outdoors. Because they grow slowly, sago palms only need repotting every three years or so. It’s a good idea to gently remove the plant from its pot every spring and replace the loose soil with fresh soil to ensure continued healthy growth. This plant grows best in a soil-based potting mix amended with sand and peat moss.

Sago palms do not like wet, soggy soil, so opt for an unglazed ceramic or terra cotta pot. The porous material will help absorb excess moisture from the soil. Choose a pot that’s only slightly larger than necessary, perhaps two or three inches larger than the roots, because this plant likes to be rootbound. Also, choose a pot with multiple drainage holes to allow the water to drain easily.

Overwintering

Sago palms are hardy down to the minimum temperatures of zone 8. They can handle brief temperature snaps at 15 degrees Fahrenheit but die when kept at 23 degrees Fahrenheit or below. To prevent plant death, provide winter protection. If you can’t take the plant indoors, then cover the plant with a burlap bag or lightweight blanket during a short cold snap. Uncover the plant when the frost melts away the next day.

Pests and Diseases

Common Pests

Sago palms don’t have serious issues with pests or diseases. But scale and spider mites can become problematic. Look out for foliage damage or discoloration, as well as tiny bugs among the fronds. Aim to use an organic insecticide like insecticidal soap or neem oil before turning to harsher chemicals, and make sure your plant has enough humidity and airflow.

Common Problems 

Sago palms are easy to grow and maintain, but they require specific growing conditions to keep them healthy. Often small changes like watering schedule, checking water drainage, and the correct soil type can go a long way.

Yellowing Leaves

Yellowing is common in older, outer leaves and can be attributed to the life cycle of that leaf. The bottom-most, lower ring of leaves is the oldest. Do not remove the leaves until they turn brown and die.

Insects can also cause yellowing, and if you haven’t noticed any bugs on the plant, you can suspect a manganese deficiency in the soil. The yellowing will appear to affect all of the fronds. You can apply manganese sulfate powder to the soil two to three times annually to correct the problem. Yellowed leaves won’t turn green, but subsequent foliage should look healthy.

Wilting Leaves and Leaf Drop

Root rot. is a fungal infection often caused by too much water or using poorly draining, compacted soil. The fungus gets to the roots and destroys the plant from within. Another sign of root rot is an oozing, black sore or stain on the trunk. Root rot results in leaf wilt, discoloration, and leaves falling out. If you catch it early, you can remove infected foliage and treat the plant with a fungal spray or systemic fungicide. You might be able to save the plant. If the plant has lost too many leaves, it may be too far gone to salvage, but it’s worth a try.

Little Black Spots on Foliage

Even if your plant has recovered from an insect strike, you might notice small black spots that look like dirt or soot on leaves or stems. Sooty mold is a fungus that grows on the secretions that tiny bugs leave behind. This fungus can be washed off the sago’s leaves with a steady stream of water on each spot. The fungus will not feed on the sago, but it will grow if left unchecked and can overtake a plant’s leaves, affecting chlorophyll production and photosynthesis.

III. Uses and Benefits 

The pith contains edible starch, and is used for making sago. Before use, the starch must be carefully washed to leach out toxins contained in the pith. Extracting edible starch from the sago cycad requires special care due to the poisonous nature of cycads. Cycad sago is used for many of the same purposes as palm sago. Sago is extracted from the sago cycad by cutting the pith from the stem, root and seeds of the cycads, grinding the pith to a coarse flour and then washing it carefully and repeatedly to leach out the natural toxins. The starchy residue is then dried and cooked, producing a starch similar to palm sago/sabudana. The cycad seed contains cycasin toxin and should not be eaten as it is possible for cycasin toxin to survive the most vigorous of repeated washings. Cycasin toxin can cause ALS, Parkinson’s, prostate cancer and fibrolamellar hepatocellular carcinoma.

Aulacaspis yasumatsui is a scale insect feeding on C. revoluta, and unchecked is able to destroy the plant.

Sago Palm (Cycas revoluta) Details

Common name Cycad, Japanese Sago Palm, King Sago Palm, Sago Palm
Botanical name Cycas revoluta
Plant type Houseplant
Hardiness zone 9a, 9b, 10a, 10b, 11a, 11b, 12a, 12b
Growth rate Slow
Harvest time Fall
Height 3 ft. 0 in. - 10 ft. 0 in.
Width 3 ft. 0 in. - 10 ft. 0 in.
Sunlight Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil condition Loam (Silt)
Leaf color Green