If you have noticed that your cactus has recently turned a lighter color, is drying out or shedding leaves or other bits, there are several reasons that may be causing this. First of all, it is advisable to recognize the nature of the problem and provide immediate care, then take the necessary measures to ensure a lasting life for the cactus using suitable soil, light and environmental conditions.
Steps
Part 1 of 2: Immediate Care
Step 1. Water a cactus that is wilting more frequently
If parts of the plant appear to have dried up, shriveled, or limp (hanging or soft), it probably means it needs more water. If the soil is completely dry, water it abundantly, letting excess water drain out of the bottom end of the pot.
In the event that the earth is not dry, the problem could be due to etiolation, which causes a shrinkage of the round parts or stems. It is a sign that the plant needs more light, so it must be moved to a window facing south or west
Step 2. Cut the rotten parts
You should remove any brown or black portions - it could be the product of a fungus that occurs after excessive watering. In case the earth is completely soaked in water, remove the plant and repot it with a suitable mixture of potting soil. If it is not completely wet, allow it to dry completely before watering it again.
A typical desert cactus soil mix consists of two parts of garden soil, two parts of rough sand and one part of peat
Step 3. Provide more light to a thinning cactus
Spherical cacti with pointed ends or columnar cacti with thinned stems show symptoms of etiolation. The cause of this problem is to be found in the lack of sunlight, so try to find a place in the house that is exposed to the sun for a longer period (such as a window facing south), or that receives a more intense light (a facing West).
Step 4. Look for any traces of yellowing of the fabrics
If the portion exposed to sunlight has a yellowish or brownish color, it means that the plant is receiving too much light. Immediately move it to a shady place - such as an east-facing window - so that it receives less intense light.
Wait to see how it responds to the change of position. In the event that the yellowish parts do not improve within a few weeks, cut them down until you reach the healthy green areas
Step 5. Eliminate any insects
The main pests capable of infesting cacti are mealy bugs and red mites. The first is tiny, white in color and dusty and comes in groups; the latter are red, rather small and weave thick cobwebs between the thorns of the cactus. To remove both of these pests, apply alcohol with a cotton swab directly to the infested area, or use an acaricide for red mites.
Part 2 of 2: Ensuring a Lasting Life for the Plant
Step 1. Use a suitable soil mix
For most desert cacti it consists of two parts of garden soil, two parts of rough sand and one part of peat. This blend is designed to let the water drain well and not to harden when dry.
Use a clay pot - its weight can prevent larger cacti from tipping over, as well as allow the soil to breathe, preventing the roots from rotting
Step 2. Only water it when the soil is dry
Test the humidity by pressing a finger on the surface: if it is completely dry, wet it abundantly, letting the excess water escape from the hole in the bottom of the vase.
Step 3. Vary the watering according to the season
Cacti need a different amount of water, depending on whether they are in a growth or vegetative phase. During the dormant state from October to February, water it a maximum of once a month.
Excessive watering during the growing season is the main source of complications with cacti
Step 4. Provide enough light
Most succulents need a lot of light - keep your cactus outside in the summer, making sure it doesn't get too much rain. Start by placing it in a shady area, then gradually move it to a sunnier area to prevent it from burning. In winter, place it near a south or west facing window with the best sun exposure.
Step 5. Monitor the room temperature
Cacti prefer cooler temperatures during the growing season in winter. However, take care to keep them away from drafts, i.e. from windows that do not close perfectly and away from doors, in case they are placed on the floor. The ideal night temperature in the winter season must be between 7 and 16 degrees, so a cellar or a less hot room could be the perfect places to place them in this period.
Unless the cactus is cold hardy, be careful that the room temperature does not drop below freezing, as many species are unable to withstand frost
Step 6. Repot the plant as it grows
You will know it is time to transfer it to a larger pot if the top has become so heavy that the pot is no longer able to hold it, or if it has spread out to the point of being a couple of inches from the rim of the pot. Use a standard potting mix consisting of two parts of garden soil, two parts of coarse sand and one part of peat.
Repot it at the same level in the soil it was in the starting pot
Step 7. Remove dead roots
A typical consequence of excessive watering is the presence of rotten roots, which have been in undrained, moist soil for too long. Before repotting, gently brush away any traces of soil from the roots after removing the old soil from the original pot. Check the roots and remove the black and soft ones or the dry ones that look dead, cutting until you reach the part that is still alive.
You can prevent the roots from rotting by making sure the pot has a drainage hole in the bottom for drainage and never sits in a saucer filled with water
Step 8. Do not repot the plant right away if the roots are damaged
If you have noticed that the roots are damaged or have had to cut some dead roots when removing it from its original pot, leave the cactus out of the ground for about 10 days. This will give the parts around the damaged or cut ends time to harden. Place the plant on a sheet of newspaper, away from the sun but also from cold temperatures.
- The cactus will grow best if you repot it during the growing season (March to September);
- Most cacti should be repotted every one to two years.
Step 9. Use low nitrogen fertilizer
On most fertilizers there is a number that indicates the quantity of nitrogen, phosphorus and potassium contained (with the abbreviations N, Ph and Po). An example of a low nitrogen fertilizer suitable for cacti is of the 10-30-20 type, where the nitrogen value is 10.
- The excessive presence of nitrogen can give the plant a flaccid consistency that prevents its growth.
- Never give a cactus fertilizer during the vegetative phase (October to February).
Step 10. Remove dust and dirt
If the surface of the cactus looks dirty or dusty, it means that the plant may not be able to carry out photosynthesis properly. Remove these residues with a cloth or sponge and a solution of water with a drop of dish soap, then rinse it under the tap or with a damp sponge.
