Commonly found in the southwestern United States and northern Mexico, the Opuntia whipplei is a member of the Cactaceae cactus family, thriving—as most cacti do—in arid conditions and temperate grasslands.
Colloquially called ‘chollas’ or ‘Whipple chollas’ and renamed for scientific purposes as Cylindropuntia whipplei, this upright shrub has a hard, woody central trunk from where many bright green/purplish-green stems branch out, each topped with clusters of yellowish thorns and tubercles.
These cacti tend to lodge their spines into fur, skin, and clothing, but that aside, they are extremely easy to grow and care for, adding a unique aesthetic to the space when grown in bunches.
195 Opuntia Varieties [With Pictures]
If you’re planning to incorporate Opuntia whipplei into your garden, here’s everything you need to know about caring for it.
Like any heliophilic plant, flourishing in open environments with plenty of direct sunlight, the Whipple cholla also requires ample direct sunlight to grow and bloom.
The best idea is to place them in open spaces such as exposed gardens or outdoor balconies, as these plants will soak up the sun for as long as it’s available throughout the day!
However, during the hot summer months, give the plants a little cooling time and shade to prevent damage from extreme heat; in the wild, this damage is part and parcel of daily life and doesn’t matter so much, but if you’re growing Opuntia whipplei for decorative purposes, this becomes a necessary measure.
Like most cacti, Whipple chollas are drought-tolerant plants, used to arid conditions and extremely infrequent rain.
Therefore, these plants do not require frequent watering; in fact, they’re more likely to die of root rot than underwatering in a home garden!
Once you’ve potted your Opuntia whipplei, water it slowly, waiting in between to see if the water flows out of the bottom—a sign to stop watering.
If you have a tray beneath the pot, ensure that you empty the water that’s flowed out of the pot and collected in the tray, preventing water accumulation.
Opuntia whipplei cacti grow during the spring, summer, and fall months, during which time it is necessary to water them weekly once or twice so that the soil is always slightly wet.
During the cold winter months, water is just enough to prevent excessive drying of the soil (generally, watering once a week achieves this).
It is also advisable to use distilled water or rainwater to water your Whipple cholla, as tap water contains a lot of added minerals, chemicals, and salts that could cause soil compaction in the long run.
Another helpful tip is not to splash water on the plant’s stem while watering; doing so could result in rotting.
Opuntia whipplei cacti love soil that is rich in gravel, water-permeable, and fertile, with a pH value between 6 and 7.
When grown at home or in non-wild conditions, the ideal soil combination is 20% coco coir/peat moss, 60% vermiculite, and 20% sandy soil, with or without a tiny amount of organic potting soil.
Vermiculite ensures air permeability—highly essential as the roots of the Opuntia whipplei are extremely susceptible to root rot when oxygen is deficient.
Therefore, the soil should also drain well, in addition to being air-permeable (a good way to check this is to see if water quickly drains through the soil, instead of pooling at the surface and then slowly getting absorbed by the soil).
Repotting and loosening the soil annually will also help maintain air permeability.
For better soil fertility, vermicompost and eggshell powder can also be incorporated.
In their vegetating months (spring, summer, and fall), your Whipple chollas should be fertilized with liquid fertilizer once a month.
Keep off the fertilizer in the winter months; if you’re repotting in spring or fall, you can incorporate a tiny amount of slow-release fertilizer into the soil—this will sustain the plant through the winter months.
Opt for phosphate-potassium fertilizers for the periods before and after the cactus blooms, whereas nitrogen fertilizer is best for the seedling phase.
Make sure the concentration of fertilizer is as low as possible; over-fertilizing is always more harmful than under-fertilizing; a great way to prevent the former is to use low-concentrate fertilizers and fertilize several times.
Slow growth in the base, accompanied by yellowing, could be a sign of over-fertilizing—if you notice this in your plant, stop fertilizing immediately.
As mentioned earlier, Whipple chollas thrive in desert-like conditions, with high temperatures, strong sunlight, and minimal rainfall.
They also do well in subtropical and tropical regions with the same conditions.
The ideal temperature that Opuntia whipplei plants enjoy is between 68 and 95°F; at temperatures lower than 50 or higher than 95, plant growth rate reduces and dormancy starts setting in.
The plant’s surroundings should be well-ventilated and the humidity in the air shouldn’t be high, so water accumulation and high-humidity areas should be avoided.
Some of the pests and diseases that Whipple chollas are prone to are:
- Anthracnose: Small black dots that appear in a spiral pattern on the plant’s upper parts, caused by extreme humidity and temperatures.
- Stem Rot: A common disease caused by a range of reasons, such as insects, cold-induced wounds, and infected soil.
- Root-knot Nematode: Caused by insects that darken the stem and leaf surfaces, eventually resulting in death.
- Spider Mites: Tiny insects that build web-like structures and cause the leaves to turn red and yellow.
- Aphids: Tiny pests that cause yellowing and distortion in growth.
- Other Diseases: These include mealybugs, soft rot, viruses such as local necrosis and mosaic leaves, rodents, and dry rot.
A great thing about Whipple cholla is that it requires minimal pruning. Just remove any dead/withered branches and flowers to prevent any potential unhealthiness from spreading.
Pot the plant when the temperatures outside are between 59 and 68°F, generally during fall and spring.
While seeding, the air humidity should be high, and you should cover the soil with a plastic film to maintain this humidity. The film can be removed once germination starts.
Use clay flower pots as these are permeable and ensure that they are not too small or too large, as this could cause restrictions in root development and water accumulation, respectively.
Repotting is unnecessary for large cholla plants, but if you’re growing them in pots, repot once a year—lift the whole plant, get rid of old soil hanging to it, place it in another container, and fill the container with potting soil.
How to Propagate Opuntia whipplei
Division and grafting are effective methods to propagate Opuntia whipplei.
To divide, cut off the stem’s lateral branches or the plant’s tip and plant this in soil; in a few months, you’ll notice small shoots growing up.
For grafting, you’ll need a suitable rootstock. Once you have it, cut off its tip, put the Whipple cholla, with roots removed, in the rootstock’s center, and secure it with rope. In a couple of weeks, you’ll see the parts growing together, and you can now remove the rope.
You could also try seeding, as mentioned earlier.