- Light Preference/Tolerated (Bright Direct Light)
- Low Watering Needs
- Mature Height 6-12 inches
- Pet Safe
Where the Red Cap Cactus (Gymnocalycium mihanovichii var. friedrichii "Rubra" graft) can be seen in garden centers and grocery stores alike, few understand just how interesting this colorful cactus is. The red top of the cactus, often confused for a flower, is a separate species that lacks chlorophyll, giving the plant its fiery ruby color. Because these beautiful mutants cannot survive on their own, they are expertly grafted onto another green cactus species that provides nutrients and energy to the whole plant. These easy-to-care-for succulents require infrequent watering and are an eye-catching addition to a bright space.
Best Locations For Growing Red Cap Cactus
Like other cactus and succulent plants, the Red Cap Cactus, also called Moon Cactus, will thrive in a spot that receives plenty of bright light, even tolerating direct sunlight. Pair the Red Cap with other succulents and cacti in a planter and admire its bright color and unique shape. These small plants fit nicely in a kitchen windowsill or on a patio tabletop as well.
Red Cap Cactus Sunlight Requirements
Place the Red Cap Cactus in a warm spot where it can get bright light most of the day, such as an east-facing window. This cactus can tolerate direct sunlight from a south- or west-facing window, though it may need protection from intense afternoon sunlight. Some signs that the light is too bright include fading color, called bleaching, and white or brown sunburn scabbing. Cacti are not typically tolerant of medium to low light, and the Red Cap Cactus is no exception. Low light levels may lead to etiolation (stretching toward light), loss of color, and an increased risk of root rot.
Red Cap Cactus Care
Cacti and succulents prefer to be in smaller, tighter pots with less excess soil around their roots. This allows them to dry out more quickly and fully in between waterings. For this reason, the Red Cap Cactus can stay in the same pot for years without needing additional space to grow. When you do decide to repot, choose a pot that is only an inch or two larger in diameter and with plenty of drainage. Cacti do best when planted in well-draining cactus or succulent soil.
Watering Red Cap Cactus
Cacti and succulents are able to store water in their stems. Because of this, it is a lot easier to overwater a cactus than it is to underwater it. Allow the soil of the Red Cap Cactus to dry out completely before watering deeply and fully. You may have to add water a few times before the soil refills the pot and holds onto water. In warmer months, you may need to water as much as once or twice a month depending on lighting, temperature, and humidity. In winter, cut back on watering significantly, only watering when the soil has completely dried.
Feeding Red Cap Cactus
The Red Cap Cactus will appreciate light fertilization in the spring and summer months. Use a cactus and succulent-specific fertilizer once a month while the plant is growing. Fertilizing in the winter is not necessary as indoor plants typically slow down their growth significantly.
Red Cap Cactus Information
Light Exposure: Bright Direct Light |
Care Requirements: Easy |
Watering Requirements: Below Average - Let the soil dry completely, then, water deeply. |
Pet Friendly: Yes |
Kid Friendly: Yes |
Air Purifier: High |
Habit: Clumping |
Growth Rate: Slow |
Mature Height: 6-12 inches |
Mature Spread: 2 inches |
Flowering: Yes |
Flower Color(s): Pink, Purple |
Flower Shade/Description: Pale-Pink to Purplish-Pink |
Fragrant: No |
Foliage Type: |
Foliage Color(s): Green, Pink, Red |
Foliage Description: Green/Red/Pink |
Temperature: 25° - 50°F (-4° - 10°C) |
Humidity: Low |
Common Name: Red Cap Cactus |
Other Name(s): Ruby Ball |
Scientific Name: Gymnocalycium mihanovichii var. friedrichii "Rubra" |
Plant Type: House Plant |
- SKU:
- Cact_Graft_Red-HP
Container Sizes
Please Note: The pictures below are to give a general representation of the different container sizes. The actual size/ages of plants are estimates and will vary based on type of plant, time of year, last pruning & many other factors.

2" Pot
Plant Age:
~ 2-6 months
Plant Size:
~ 2"-4"
Pot Size:
~ 1.9"H x 2"W
Volume:
~0.12–0.15 quarts

3" Pot
Plant Age:
~ 3-6 months
Plant Size:
~ 2"-6"
Pot Size:
~ 2.5"H x 3"W
Volume:
~ 0.3 quarts

4" Pot
Plant Age:
~ 6 months
Plant Size:
~ 5"-10"
Pot Size:
~ 3.5"H x 4"W
Volume:
~ 0.75 quarts

6" Pot
Plant Age:
~ 6-12 months
Plant Size:
~ 8"-16
Pot Size:
~ 5"H x 6"W
Volume:
~ 1.5 quarts

8" Pot
Plant Age:
~ 1-2 years
Plant Size:
~ 12"-24"
Pot Size:
~ 6"H x 8"W
Volume:
~ 3 quarts

10 Pot
Plant Age:
~ 2-3 years
Plant Size:
~ 16"-36"
Pot Size:
~ 7.25"H x 10"W
Volume:
~ 4.5–5 quarts

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