Q. The cycad I bought in a container a few years ago is turning yellow even though I moved it out of direct sun and into the dappled shade of a vitex tree. Can you advise whether I still need more shading to correct the yellowing? I’m afraid to plant it in the ground because it might freeze.
A. I don't think the yellowing is a problem from intense sunlight. This plant can handle full sun in our Mojave Desert with no problems if the soil has been prepared adequately, organic amendments are added to the soil every year or two and water is available when needed. It’s easier to grow, however, on the East sides of buildings where it gets some protection from the late afternoon sun.
From your picture, it seems it is growing in the same container that came from the nursery. If this is true, all the organics in that original soil are gone. Even if you are adding fertilizer to the container, the plant leaves yellow because the soil is “worn out”. Basically, the plant is growing in the container hydroponically (only water and whatever fertilizer it gets).
It is important to add organic amendments to all soils on a regular basis to maintain good plant health, improve its tolerance to our harsh desert climate and stay resistant to diseases.
Plants grow better and are healthier (they can withstand more problems) if they are grown in the ground and in a healthy manner. Your cycad is growing in an old, “tired” soil that has not been amended, in a container that’s too small and who knows if it’s getting water when needed.
Pick a spot for it and get it planted. Plants growing in containers are difficult to manage. In the ground, it can grow in full sun if surrounded by other irrigated plants. This plant will be healthier if the soil is covered with woodchips rather than rock. It is not a desert plant for sure, so it needs to be planted and watered with other non-desert plants and cared for in a non-desert way.
These plants will tolerate temperatures as low as 20°F but may show some winter damage (bronzing) to the leaves at 25F. Remember, winter cold is worse if the plant is growing in a windy location.
When planting it this Fall, use a quality compost and mix it equally with soil taken from the planting hole. When planting, use this amended soil and flood the hole with water as soil is added. Make sure it’s planted at the proper depth; not too shallow nor too deep.
Cover the soil surrounding it with woodchips from local trees trimmings. These will degrade over time and add more organics to the soil. Your cycad will appreciate this! Fertilize it lightly once a year with a tree and shrub or lawn fertilizer. Apply it under the leaves, not too close to the trunk, and water it in.
Leaves that are yellow will stay yellow until removed in a couple of years when the plant gets older and bigger. But the new growth coming from the trunk should be dark green if planted correctly. This new growth eventually replaces yellow leaves as they are removed. Water the same as you would other trees and shrubs in the landscape. Apply about 5-10 gallons of water each time it is irrigated.