Consider the following reasons for your Thanksgiving cactus’s leaves turning yellow. Your plant maybe pot bound if the container is tightly packed with roots. Consider moving your plant to a container one size larger. The recommended soil mix for a Thanksgiving cactus is one-part sterile potting mix, two parts peat moss, and one-part sharp sand or perlite. After repotting water well and withhold fertilizer for a month. However, do not rush to repot because this plant thrives in a crowded pot. As a rule, do not repot the plant unless it has been at least two or three years since the last repotting.

Yellow Thanksgiving cactus leaves may be a sign that the plant has a disease known as root rot, which is caused by excessive watering or poor drainage. To check for root rot, remove the plant from the pot and inspect the roots. Diseased roots will be brown or black, and they may have a mushy appearance or a musty odor. If you notice root rot, trim infected parts of the roots and move the plant into a clean pot with fresh potting mix.

Thanksgiving cactus leaves turning yellow may be an indication that the plant is lacking necessary nutrients, especially if you do not fertilize regularly. Feed the plant monthly from spring until mid-autumn using an all-purpose liquid fertilizer at half strength. Additionally, Thanksgiving cactus is said to have a high magnesium requirement. As such, some resources recommend a supplemental feeding of one teaspoon of Epsom salts mixed in one gallon of water applied once monthly throughout spring and summer. Stagger feedings and do not apply the Epsom salt mixture the same week you apply regular plant fertilizer.

Propagating a new plant from the five leaves may be a good idea to help save your plant.

The following article may give you more information on your Thanksgiving cactus: Holiday cacti | UMN Extension