When a cactus looks wilted, it might be receiving improper amounts of water, need repotting, live in the wrong environment or have a disease such as fusarium wilt. To identify the cause of a wilting cactus, the gardener should consider the care given to the cactus to see what changes might improve its health.
Too little or too much water can cause a cactus to wilt. Gardeners often assume that cacti require less water than they do, because they are desert plants with a reputation for needing very little water. While gardeners should allow cactus soil to dry out between waterings, the University of California at Davis also recommends that gardeners throughly water the plants when they water cacti. At the same time, overly wet roots cause wilt, discoloured foliage and even death. Let cacti dry out thoroughly between waterings, keep in them in soil with good drainage and use pots with drainage holes.
Fusarium wilt disease causes older leaves to wilt and die, followed by younger leaves and the rest of the plant, reports the University of California. It often starts with wilt on one side of a plant, spreading from there. Fusarium wilt attacks plants through the soil, and gardeners can avoid this disease by planting potted cacti in pasteurised potting soil and avoiding outdoor garden areas where plants had the disease in the past.
Christmas and Easter Cacti
Most cacti come from desert environments in direct sunlight, but Christmas and Easter cacti come from woodlands, where they require more humidity than other cacti. Gardeners in dry climates can provide moisture by occasionally misting them with a spray bottle. As too much direct sun can cause Christmas and Easter cacti to wilt, gardeners should keep them in areas with bright, but indirect, sunlight throughout the day.
If a change in water or light amounts does not fix a wilting cactus, consider repotting, which provides an opportunity to move the plant into a disease-free soil mixture designed specifically for cacti. If the roots seem cramped, choose a slightly larger pot to accommodate the plant. You can also remove severely damaged or dying parts of the plant. The North Dakota State University Extension also recommends waiting to fertilise the plant until after it starts to grow again, instead of while it is wilting.
If a cactus continues to wilt without signs of recovery, try to propagate it by taking cuttings of the healthiest leaves on the plant. Even if the original plant dies, some cuttings should survive and allow the owner to keep enjoying cactus plants. Let the cuttings sit out on the counter for a day or two, then stick the cut ends in new pots with pasteurised potting soil. The cuttings should sprout new roots easily.