Origin
Cereus robinii (Lem.) L. Benson var. keyensis (Britt. & Rose) L. Benson ex Long & Lakela is a species of cactus that is native to the Florida Keys in the United States.
Common Names
The plant is commonly known as the Key Cactus, Biscayne Cactus, or Biscayne Night-blooming Cereus.
Uses
The Key Cactus is primarily used as an ornamental plant due to its interesting appearance and unique night blooming flowers. The flowers are large and fragrant, opening at night and closing by morning. The plant also produces edible fruit, although it is not widely consumed.
General Appearance
The Key Cactus is a climbing or bushy cactus that can grow up to 10 feet tall. The stems are green and have 3-4 prominent ribs with spines along the edges. The plant is covered in small, bristly hairs that give it a fuzzy appearance. The flowers are white and up to 8 inches across, blooming in late spring to summer. The fruit is green and oblong, up to 3 inches long, and contains small, edible seeds.
Light Requirements
Cereus robinii var. keyensis typically thrives in full sun to partial shade. It requires at least six hours of direct sunlight each day to grow properly. Lack of adequate sunlight can lead to slow growth and spindly stems.
Temperature Requirements
This plant thrives in warm climates and does well in temperatures that range between 70 to 90 degrees Fahrenheit. Cereus robinii var. keyensis is not tolerant of frost, and temperatures below 50 degrees Fahrenheit can lead to stunted or damaged growth.
Soil Requirements
The plant grows well in well-draining soils with a pH range of 6.0 to 7.0. Cereus robinii var. keyensis grows in rocky or sandy soils in the wild, so it tolerates poor soil conditions. However, for optimal growth, it is recommended to use a mix of equal parts of sand, perlite, and peat moss.
Cultivation Methods for Cereus robinii var. keyensis
Cereus robinii var. keyensis is a cactus species that grows well indoors and outdoors. Growing this plant requires knowledge of its natural habitat and growing conditions.
When planting this cactus species, it is best to use a sandy or gravelly soil mixture. The soil should have good drainage properties because Cereus robinii var. keyensis does not like standing water.
It is important to note that this plant requires ample amounts of sunlight. It should be positioned in an area where it can receive direct sunlight for at least six hours each day. If grown indoors, place the cactus near a window where there is abundant natural light.
Watering Needs for Cereus robinii var. keyensis
Cacti species like Cereus robinii var. keyensis are adapted to survive in arid conditions, which means they do not require frequent watering. Over-watering can lead to rotting of the roots or the development of fungal diseases.
When it comes to watering Cereus robinii var. keyensis, allow the soil to dry out completely before watering again. During summer, the cactus should be watered at least once a week. In winter, watering can be reduced to once every two to three weeks.
Fertilization for Cereus robinii var. keyensis
Applying fertilizer at the right time and in the right quantity can help promote healthy growth and flowering of Cereus robinii var. keyensis. Fertilization is one of the most important factors that contribute to the healthy growth of this cactus.
Fertilize the cactus once every two to three months during the growing season. Use a liquid fertilizer that is specifically formulated for cacti and succulents. Avoid applying too much fertilizer, as this can cause damage to the roots and reduce the plant's growth.
Pruning of Cereus robinii var. keyensis
Cereus robinii var. keyensis requires minimal pruning, but it helps to remove any dead, damaged, or diseased stems or branches. This can be done by using a sharp, sterilized pair of pruning shears.
If the plant becomes too large for its space, it can also be pruned to reduce its size. Regular pruning can help promote healthy growth and prevent the plant from becoming too leggy.
Propagation of Cereus robinii (Lem.) L. Benson var. keyensis (Britt. & Rose) L. Benson ex Long & Lakela
Cereus robinii (Lem.) L. Benson var. keyensis (Britt. & Rose) L. Benson ex Long & Lakela can be propagated through different methods. Here are some of the most common ones:
Seed Propagation
The easiest way to propagate Cereus robinii (Lem.) L. Benson var. keyensis (Britt. & Rose) L. Benson ex Long & Lakela is by using seeds. The seeds are readily available at most nurseries or can be collected from mature plants. To start propagating using seeds, follow the steps below:
- Soak the seeds in warm water for at least 24 hours before planting to help soften the hard outer coating and improve germination rates.
- Fill a container or pot with a well-draining soil mix and make a shallow hole in the center.
- Place one or two seeds in the hole and cover them with soil.
- Mist with water and cover the container with plastic to maintain humidity.
- Place the container in a well-lit area, but not in direct sunlight.
- Keep the soil lightly moist until germination occurs, usually within two to four weeks.
- Once the seedlings have emerged, remove the plastic cover and move the container to a brighter spot.
- Continue watering and feeding the young plants until they are large enough to transplant.
Stem Cuttings
Cereus robinii (Lem.) L. Benson var. keyensis (Britt. & Rose) L. Benson ex Long & Lakela can also be propagated from stem cuttings. Follow the steps below to successfully propagate Cereus robinii (Lem.) L. Benson var. keyensis (Britt. & Rose) L. Benson ex Long & Lakela using stem cuttings:
- Select a healthy stem from the parent plant and cut a small piece, about 6 inches long.
- Let the cutting dry for a few days in a shaded spot to allow the cut area to callus over.
- Fill a container or pot with a well-draining soil mix and make a small hole in the center.
- Dip the cutting end in a rooting hormone and insert it into the soil hole.
- Mist the soil and cover the container with plastic to maintain humidity.
- Place the container in a well-lit area, but not in direct sunlight.
- Keep the soil lightly moist until roots start to form, usually within two to four weeks.
- Once the roots have formed, remove the plastic cover and move the container to a brighter spot.
- Continue watering and feeding the young plant until it is large enough to transplant.
Disease Management
Cereus robinii var. keyensis is prone to fungal infections that would lead to stem rot. The rotting would begin at the base of the stem, increasing from there and ultimately leading to the death of the plant. The best way to manage the disease is through prevention measures, which may include avoiding overwatering, providing good air circulation, and avoiding compact soil.
If the disease has already taken root, the best way to manage it would be through cutting off the infected parts and allowing the plant to dry. It would also help to apply a fungicide to the remaining parts to prevent further infection.
Pest Management
Cereus robinii var. keyensis is prone to infestation by mealybugs and spider mites. Mealybugs are commonly found near the base of the spines while spider mites would be found on the stem. The insects can cause deformities in the plant as well as attract other pests and diseases.
The best way to manage the infestation is through early detection and elimination measures. You may wipe the insects off with alcohol or insecticidal soap while ensuring that you clean the base and undersides of the spines. For spider mites, you may spray your plant with a stream of water or use insecticidal soap. It would also be best practice to isolate the infected plant to avoid spreading the infestation to other plants.
