We transplant cacti!
Every 3 or 4 years, cacti must be transplanted (or rather transplant from one pot to another) . Of course, due to the fact that these flowers grow slowly, the new pot will be a little more than the same. During the transplant, use special soil for cacti, which is sold in stores. This will help you avoid an incorrectly composed mixture.
Try not to bury the fleshy parts of the plant and add small stones or gravel to the soil: this will save the cactus from excessive humidity.
Like other plants, cacti do not like dust that deprives them of light. To remove dust, take a small brush and go between the cactus needles (make sure that you do not accidentally damage the plant).
How to transplant them, they are thorny?
First, put on household gloves. For complex actions such as transplanting, wrap your cactus with a band of newspaper paper. It is very easy and practical.
A little water and fertilizer
It is fair that too frequent watering is destructive for cacti. However, too overdry cacti, especially in the summer, is also risky.
If you want to achieve cacti flowering, you should regularly fertilize them, about 1 time per month from April to September.