How to Save a Dying Cactus

The signs of a cactus turning yellow, drying out, or having drooping leaves or stems can be caused by several factors. First, you need to identify the problem and apply the necessary emergency care, then create the best conditions for the cactus to thrive long-term by providing suitable soil, light, and environment.

Water the wilting cactus. If part of the cactus shrivels, wrinkles, or wilts (drooping or looking weak), it probably needs more water. If the soil is completely dry, water it thoroughly until it drains from the bottom of the pot.

• If the soil isn’t dry, the cactus might be experiencing yellowing, where round or stem-like parts shrink. This indicates it needs more sunlight, so move the pot to a south-facing or west-facing window.

Remove the rotting parts of the cactus. Any brown or black areas on the plant need to be cut away. Rotting can occur due to fungus when overwatering. If the soil is waterlogged, remove the plant and repot it in the right soil mixture. If the soil is not soggy, let it dry out completely before watering again.

• A standard soil mix for desert cacti consists of 2 parts garden soil, 2 parts coarse sand, and 1 part peat moss.

Provide additional light for a shriveled cactus. The sharp tips of spherical cacti and other round cacti, or the shriveling and thinning of the stems of tall-cactus species, indicate a condition called yellowing. This happens due to insufficient light. Find a location in your home with extended sunlight exposure (south-facing window) or higher light intensity (west-facing window).

Check for yellowing on the cactus skin. If the cactus skin on the sun-exposed side turns yellow or brown, it means the plant has been overexposed to the sun. Quickly move the cactus to a cooler spot, such as an east-facing window with gentler sunlight.

• Observe how the cactus reacts to being relocated to a shadier spot. If the yellow areas do not improve after a few weeks, trim the affected areas, leaving only the healthy green portions.

Eliminate pests. The primary pests that harm cacti are mealybugs and spider mites. Mealybugs are tiny, white, powdery, and appear in clusters. Spider mites are small, reddish, and create webbing between the cactus spines. To eliminate both, you can use cotton balls soaked in rubbing alcohol to directly apply to the affected areas. You can also use miticides to eliminate spider mites.

Use the appropriate soil mix. For most desert cacti, the ideal soil mix consists of 2 parts garden soil, 2 parts coarse sand, and 1 part peat moss. The soil mix must be well-draining and should not compact when dry.

• It’s also recommended to use clay pots, as the weight of these pots prevents large cacti from tipping over; they also promote good soil aeration, helping prevent root rot.

Water only when the soil is dry. To check the moisture level, press your finger into the surface soil. If the soil is completely dry, water thoroughly until water drains from the pot's bottom hole.

Adjust watering schedule according to the season. The watering needs of cacti vary depending on whether the plant is growing or dormant. During the growing season (March to September), water the cactus about once a month. During dormancy (October to February), limit watering to a maximum of once a month.

• Overwatering during the cactus's dormancy period is a major cause of problems for the plant.

Provide adequate sunlight. Most cactus species require plenty of sunlight. In summer, place the plant outdoors, but avoid excessive rain exposure. Start by placing it in a shaded area, and gradually move it to sunnier spots to avoid sunburn. In winter, place the cactus in a south or west-facing window, where it can receive the most sunlight.

Monitor indoor temperature. Cacti prefer cool temperatures during their dormant period. However, avoid placing them in drafty areas—keep them away from windows with drafts and off floors near doors. The ideal nighttime temperature during winter should be between 7 - 16°C, so a basement or an unheated room is suitable for storing the plant during this time.

• Unless growing a cold-hardy cactus species, avoid letting indoor temperatures fall below freezing, as most cacti cannot tolerate frost.

Repot the cactus based on its growth. You'll know it's time to move the cactus to a larger pot when the top grows heavy and causes the pot to be unstable, or when the cactus is within 2.5 cm of the edge. Use a soil mix consisting of 2 parts garden soil, 2 parts coarse sand, and 1 part peat moss. Replant it at the same depth as it was in the previous pot.

Trim the dead roots. A common effect of overwatering is root rot, caused by prolonged exposure to wet soil with poor drainage. Before repotting, gently brush off excess dirt from the roots after removing the root ball from the old pot. Inspect the roots and remove any blackened or decayed sections. Cut as close to the healthy roots as possible. To prevent root rot, always use a pot with drainage holes and avoid letting water accumulate in the saucer.

Don’t rush to repot immediately after root damage. If the roots are damaged when you remove the cactus or need trimming, let the plant sit outside for about 10 days. This allows it to form a callus over the damaged areas. Place it on a paper in a shaded area, avoiding direct sunlight but not too cold. Cacti grow best when repotted during their growing season (March to September). Most cacti should be repotted every one to two years.

Use a fertilizer with low nitrogen content. Most fertilizers display the ratio of nitrogen, phosphorus, and potassium (N-P-K). For cacti, a suitable fertilizer is 10-30-20, where nitrogen makes up 10%. Too much nitrogen can cause the cactus to become soft and hinder its growth. Never fertilize cacti during their dormant period (October to February).

Clean off the dirt. Dust on the cactus can reduce its photosynthetic ability. Use a cloth or sponge soaked in a water and dish soap solution to gently wipe the dust, then rinse under running water or use the sponge with just water to clean.