Sago palm slowly develops a coarse, rough stem or trunk that adds about 1 inch of length and girth a year. Evergreen leaves emerge only from the tip of the trunk when it's young. Only after 40 or 50 years will a healthy sago palm trunk develop large side branches. New leaves only emerge from the growing tips on the main trunk or primary side branch tips. Typically one new flush of new leaves emerge from the growing tip each year, usually in early summer. If fertilized properly, with lots of nitrogen, a second flush of leaves may appear in late summer in tropical regions.
Cutting off or damaging the growing tips on the trunk or branch arms on a sago palm ends leaf production from that area. Likewise, if you saw off a trunk or branch on the plant, new growth doesn't sprout from the pruning wound. Yellow or brown dead leaf fronds may be pruned away by cutting them off at their base as close to their attachment to the trunk as possible. Do not prematurely remove healthy green fronds as they photosynthesize light and make food. Loss of green leaves slows growth even more and can deplete the energy stored in the trunks and roots. Knobby stem growth from the main trunk may be cut off to prevent branching or new leaves to tidy up the plant.
Reasons for Leaf Pruning
When the leaves of a sago palm are killed by extreme winter cold or yellowing as a result of a severe infestation of scale insects, pruning off leaves is warranted. If possible, retain any green healthy leaves in the crown so that some photosynthesis still occurs. A new flush of leaves can take anywhere from two to 12 months to develop. The warmer the climate, the faster the new leaves emerge.
The ideal time to remove any dead or sick leaves is in late winter to mid-spring. This coincides with the plant's end of winter dormancy and the plant naturally is expending energy to send out numerous soft new leaves from the growing tip. The least desirable time for pruning is in late summer or early fall, especially in climates where frosts and freezes occur in fall and winter. There is not enough warmth for new leaves in fall, so the plant must endure an extended dormancy until the next spring.