Cycads are often lumped together with palms in horticulture and the nursery trade. At surface level this appears to make sense. At first glance, cycads look like palms; they have large, dark green leaves with folded leaflets that are clustered around the apex of the stem.
Since cycads are generally rare in horticulture and the nursery trade, it is easier to lump them with the far bigger and better known palm group. But don’t let their looks mislead you. Cycads are quite different from palms and deserve recognition and a different type of care. If we treat cycads like palms, we may sacrifice their health.
Over a hundred million years of evolutionary history separates these two groups. Cycads are more closely related to our Christmas trees than our Christmas palms. Like Christmas trees and other conifers, cycads produce cones, not flowers (like palms). Yet we still lump them with palms, giving them the same fertilizer and bad trim jobs.
It’s time to take a closer look at our cycads to understand their horticulture.
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Let’s start with reproduction. Cycads are dioecious — there are separate male and female plants. Male cones produce pollen. They emerge once a year, usually in groups of three or more, and after the pollen is expended, they wither away.
Female cones produce seeds and, unlike male cones, they stay on the cycad for years, continuing to use nutrients and energy regardless of seed viability. Female cycads epitomize stubbornness. Even if the seeds are not fertilized, the cone will continue to grow. This is a huge expense for the female cycads.
This is quite different from palms. If palms’ small, inconspicuous flowers are not pollinated they are simply discarded and fall off the palm. No more time and energy is spent.
While appropriate fertilization is extremely important for palms, it is even more so for cycads. Since the female cycads retain the cones for so long, they need nutrients on a more regular schedule. For the palms, I recommend a twice a year application of 180- or 360-day 13-3-13 fertilizer (12-4-12 or 11-4-11 is also great) with lots of micronutrients. For cycads, I recommended a 60-day 11-4-11 with lots of micronutrients every three months. While male cycads may survive on a palm fertilizer schedule, female cycads need more nutrients.
A cycad fertilization schedule will also encourage better leaf production. Leaf production is also quite different in cycads and palms. Cycads produce many leaves at once; they emerge as a flush every few months. Palms on the other hand produce one leaf at a time.
For both groups of plants, inappropriate leaf removal is extremely detrimental. For cycads, removing green leaves is very risky especially if done before the new flush is completely expanded. Emerging flushes in cycads are extremely sensitive to injury. If something happens to the new flush and the old flush is removed, the cycad will have no functioning leaves. In both palms and cycads, green leaves should not be trimmed because as they die they send their nutrients back to the plant. Discoloration is often a sign of deficiency in the bud and removing a deficient leaf only makes the plant more deficient.
Cycad history, form and horticulture are quite distinct from the palms. By lumping cycads into palm horticulture, their health is often sacrificed. Cycads are beautiful ornamentals and we should take better care of them.
Sara Edelman is the palm and cycad manager at Fairchild Tropical Botanic Garden.