Use a pre-formulated succulent soil or prepare your own planting mix that ensures good drainage. One part potting soil, one part sand is a simple recipe to start with. You may line your container or planting hole with gravel for increased drainage. If planting in ground, dig a hole slightly deeper and twice the width of your plant's root ball, then backfill with your cactus soil and gently press into place. Transplant out once soil temperatures reach 55-60°F. Containers should be two to three times the width of the root mass, ideally on the shallower side to allow soil to dry out completely and prevent root rot. If weather conditions are dry, water weekly, checking to ensure that soil dries out between waterings.
Continue to water weekly while the cactus continues to grow through the spring and summer, reducing supplemental watering (if necessary) to bi-weekly in the fall, then watering only to prevent shriveling through the dormant season. If growing in containers, an unheated greenhouse may be sufficient to overwinter. If moving inside for the winter, it is ideal to provide full indoor sun during these months, such as a well-exposed south-facing window provides, as indoor light is less intense. Your Opuntia may not require any fertilizer, but you can apply a balanced fertilizer, diluted to half strength, or experiment with one of the commercial cactus/succulent fertilizers. Some recommend a higher-potash (K) fertilizer for root development and hardiness against seasonal stresses. A higher phosphorous (P) formula, especially at bloom time, will promote blooming and fruiting. Nitrogen (N) will encourage more green growth and favor pad production, but should be moderated, especially as young plants are rooting out and getting established, and should never far exceed the other N-P-K numbers. Natural or organic fertilizers are highly recommended as they are less likely to burn the cactus, should be applied once or twice a year during the growing season, and never during the dormant winter period. Up-pot only as needed, taking care when handling the root ball.
Pests & Diseases
Opuntia are prone to predation from a number of pests. Spider mites are effectively managed with a contact insecticide or other natural controls. Aphids can simply be sprayed off with a hose or managed with the same controls. Slugs and snails can be deterred with copper barriers, or managed with slug bait. A variety of scale insects attack Opuntia and can be more challenging to manage. As they feed on plant juices, these pests form a protective barrier that can range in appearance from powdery to the Cochineal insect's small cotton-like fibers. These varied species target different portions of the plant, many occupying only the shaded areas and undersides of the pads. They can be blasted off with the hose sprayer, taking care not to damage the plant tissue, but may require manual removal with tweezers or a brush. A systemic insecticide, not generally labelled for use on edible crops, can be one of the only ways to manage an infestation. The biggest pest of Opuntia, mealybugs, are likewise difficult to get rid of without a systemic, and attack the entire plant; in the presence of mealybugs, you may be advised to inspect the roots. Rot typically starts from the roots, spreading upwards and eventually affecting the entire plant. Rots can vary in color from red to black, but will have a foul odor and a softening and sliminess of the affected plant tissue. This is very hard to control once it starts and can be prevented by avoiding overwatering and ensuring good drainage. The only solution is to remove the infected portions of the plant. Corking is a browning and hardening of cactus tissue, a natural process of aging which spreads from the base up. If you see discoloration from the top down, it is likely spider mites, sunburn or some other issue that should be dealt with.
Very well-drained, not too rich in organic matter.
Full sun, though O. ellisiana can tolerate some shade and may even prefer a bit of shade or filtered light in hotter regions.
20°F or below.
Harvest the cactus pads for use as vegetables. Most prefer the tender young pads. The peeled pads can be served raw, pickled, steamed for a few minutes, or sautéed into any dish, but should not be overcooked to preserve their texture. In late summer, the reddish-purple fruit should be harvested when they are still firm but give slightly to the touch. Fruit taste of watermelon, but with a unique texture, and are great for juicing, jams or many other preparations. Flavor is said to be enhanced with a bit of lemon juice. Do not touch a knife to the fruit until just prior to consumption, as this will cause browning of the fruit if left to sit. Young pads can be cut or twisted off at the base of the pad and left out in a shady, well-ventilated spot to heal over for a couple days before replanting.