Giant club cactus (Cereus repandus) Care Guide
Quick Care Guides
Water and Hardiness
Giant club cactus is distributed throughout tropical, subtropical, and semi-desert regions with scarce rainfall, intense sunlight, and hot temperatures. The optimum temperature for growth is 20 - 35 ℃. Lower than 10 ℃ or higher than 35 ℃, growth slows and dormancy begins. The air humidity should not be too high and the environment should be well-ventilated. Avoid high humidity and accumulated water.
Giant club cactus is a heliophilic plant and needs sufficient sunlight for its growth and blooming. It can be placed on the outdoor balcony or in the garden without shade. However, long-time exposure to blazing sunlight should be avoided in hot summer, when it needs to be shaded or cooled a little to prevent high temperatures from damaging it.
Giant club cactus grows best in fertile, gravel-rich, water-permeable soil with a pH value of 6-7. The culture soil formula often used is 60% vermiculite + 20% coco coir or peat moss + 20% sandy soil. A small amount of organic potting soil can also be added. Lightweight culture media such as vermiculite can be added to improve the air permeability of the soil. Eggshell powder or vermicompost can also be added to increase the soil fertility.
Roots of giant club cactus are very sensitive to oxygen deficiency. If the soil is poorly permeable to air and water, root rot can set in. It's easy to judge permeability: when watering, water should pass through the medium quickly, rather than stop at the soil surface and slowly seep down. Repot and loosen the soil every year to ensure the air permeability of the soil.
Sow, plant, or repot in spring or fall when the temperature is 15 - 20 ℃ . Keep air humidity high when seeding. Use plastic film to cover the soil and remove it after the seeds germinate.
Use permeable clay flowerpots for potted plants. Too large a flowerpot accumulates water easily, while too small a flowerpot limits the development of roots. Before planting, expose soil to blazing sunlight and disinfect to kill pathogens.
If planted in the garden, giant club cactus prefers an area with full sun and loose soil. Remove all weeds and replace the soil if needed to ensure good water permeability and avoid root rot. Wear gloves or use tongs when planting to prevent your fingers from getting pricked. You can also wrap the plant in a towel to help you move it.
Spring, summer, and fall are its growing seasons. Water once or twice a week to keep the soil slightly wet. In winter, water less; just keep the soil from drying excessively; usually once a week. Besides, water with rainwater or distilled water rather than tap water.
Tap water contains a lot of calcium, magnesium, and other mineral salts. Long-term use tends to cause soil compaction. Avoid splashing water on its stem when watering to prevent rotting.
In growing seasons (namely spring, summer and fall), fertilize giant club cactus once a month with liquid fertilizer. No fertilizer is required in winter. A small amount of slow-release fertilizer can be well mixed into the soil when repotting in spring or fall.
Use nitrogen fertilizer during seedling and phosphate-potassium fertilizer before and after blooming. The fertilizer concentration should be as low as possible. It would be better to apply low-concentrate fertilizer several times rather than to use a high concentration. If the base is yellow and grows slowly, the cause may be excessive fertilizer, and fertilization should be immediately stopped.
Most fruits of giant club cactus are edible. Pick the fruit when they turn red. Avoid food safety issues by confirming the species with experts. Wear gloves or use scissors and other tools to harvest.
In addition to the seeding mentioned above, main propagation methods include division and grafting. To divide, cut off the tip or lateral branches of the stem with a knife and plant it in soil. After a period of time, many small shoots will grow up near the cut. When a shoot grows to proper size, it can be cut off and transplanted to form a new plant.
To graft, select a suitable rootstock. Cut the tip of the rootstock, such as the stem of pitahaya (Hylocereus undatus), and then put giant club cactus, with its roots removed, in the center of the rootstock and fix it with a rope. After 1-2 weeks, the two parts grow together and the rope can be removed.
During peak growth in spring, summer, and fall, increase water and fertilizer. Avoid sunlight exposure in the heat of the summer. Spray water around the plant to cool it down when the temperature is too high, but avoid leaving water on the stem. Avoid water accumulation in the soil. In winter, water it as little as possible or not at all, and stop fertilizer.
Why is its fleshy stem thinner and thinner as it grows?
Thin stems may be caused by insufficient sunlight, insufficient water, or fertilizer deficiency. Move the pot to a brighter place, but avoid sunburn. Increase water and fertilizer.
How do I deal with root or stem rot?
Excess water often leads to root and stem rot. Avoid accumulated water in soil. Prune rotten roots and stems and transplant to a new flowerpot in a well-ventilated place. The soil should be loose and air-permeable as far as possible.
Why doesn't my giant club cactus ever bloom?
Firstly, it may not be time for the plant to bloom. Time from seedling to blooming can range between 2-20 years or longer. Secondly, the plant may need more sunlight, temperature or fertilizer. Increase the exposure to sunlight and fertilizer appropriately, supplement the fertilizer with phosphorus and potassium, or purchase special fertilizer for promoting blooming of giant club cactus.
Why does giant club cactus turn yellow?
Giant club cactus turns yellow due to overwatering, insufficient sunlight, or pests. Giant club cactus does not require much water, and excess water leads to root anoxia and root rot. Generally, it does not need to be watered often. Water it only when the soil is completely dry. Remember to drain the water in the flowerpot tray. Sunlight can be increased, but avoid direct exposure to blazing sunlight to prevent sunburn. Remove a small amount of pests with alcohol. For large infestations, spray pesticide.
Pests and Diseases
Anthracnose often occurs in an environment with high temperature and humidity. In the early stage of the disease, non-obvious water-stain or brown spots appear on the stem. The diseased part is depressed, and small black spots in a spiral pattern appear on the upper parts. The diseased plants should be isolated, the affected leaves should be cut off and burnt, and corresponding pesticides should be used.
Stem rot is a common disease of giant club cactus, with pathogenic factors including undisinfected garbage or garden soil, wounds caused by cold, and insect damage. At the early stage of this disease, water-stained dark gray (or yellow-green to yellow-brown) spots may occur in the tissues of the diseased part, which gradually becomes soft and rots. At later stages, stem tissues rot and lose water until only dried skins and residual core remain.
Stem rot can be avoided in two ways.
- Expose the soil to blazing sunlight for disinfection, or purchase disinfected culture soil to be sure the soil is clean, loose, and permeable.
- Avoid excess water, ensure smooth drainage, and keep the plant base dry. In case of stem rot, cut off the diseased part immediately and disinfect the cut with sulfur powder or charcoal powder. Reduce watering, repot, and disinfect the soil. At the early stage, 1:100 Bordeaux mixture can be sprayed to the plant base once every 15 days for 2-3 times.
The root-knot nematode is a soft insect with white thread and two sharp ends. When the plant is affected by root-knot nematodes, the surfaces of plant stem and leaves are dark and the plant wilts with brown spots and gradually dies. To prevent root-knot nematodes, disinfect the soil and flowerpot at high temperature before planting. As root-knot nematodes are averse to high temperature and can be killed at 55 ℃, the use of culture soil disinfected at high temperature is an effective method to eliminate them.
Giant club cactus can get different kinds of viruses, but the main symptoms are mosaic leaves and local necrosis. Chlorotic spots and ringed spots can be often seen on the stem. The plant is more susceptible to viral diseases in high temperatures and drought; the main source of infection is another diseased plant. Therefore, once this disease is found, the diseased plant should be isolated or destroyed. Don't forget to disinfect tools used in grafting and care.
If the leaves turn red and then yellow, there are 6 mm insects on the leaf back, and you see spider-web structures, your plant is affected by spider mites. Wash he leaf backs with water and then spray with a special mite pesticide repeatedly. Make sure the environment is properly ventilated to avoid sweltering and drying.
Giant club cactus affected by aphids show yellowing or distorted shapes. Small pests can be seen at the tender parts. Flush them away with water. For larger infestations, spray aphids killer.
Other Uncommon Pests or Diseases
Listed below are some less common pests and diseases of giant club cactus that may also need your attention
- Dry Rot
- Soft Rot
- Mealy Bugs