|This hot summer month brings relatively less flowers than the previous months. Some cacti that flower continously during the whole summer, of course continue to flower this month too, like echinopsis, thelocactus etc. The most important point of this month is the fact that some cacti have a rest period, epecially when temperatures get very high and don't drop much during the night. This is usually true for cacti that had spring as their main growing and flowering time and not for the ones that have this month as their main growing time.
After the second half of this month a lot of cacti enter a resting period that can last until the first half of the next month. This means that, like during winter rest, these cacti don't grow, if watered they don't take on the water and are in danger of rot. So, it is important to observe the cacti and if no obvious growing signs or no flowering occurs, these cacti should not be watered or should be watered less frequent. In my case, instead of every 7 days these cacti are watered every two weeks or even less. Other cacti start growing this time of the year (echinocactus, coryphantha) or continue to grow and flower (thelocactus, echinocereus), so the above (rest period) is not true for them.
Considering the above about the resting period, I personally, don't use fertilizer this month, except from the first week and for the cacti that show growing signs this month.
During very hot days (heat waves are frequent here this month), it is useful to provide some shade during the hottest hours of the day, especially when during night the temperature stays high.
This time it is also possible that problems occur whith various insects. The epidermis of cacti should be checked for mealy bugs, scale insects and spider mites. A warning sign could be a shriveled appeareance and changes of the epidermis color. The shriveled appearance often can mistakenly be attributed to the rest period of the plant, but if the plant looks too shriveled it could be that root mealy bugs are present.
Echinopsis oxygona, Gymnocalycium damsii, Gymnocalycium michanovichii, Gymnocalycium michanovichii var stenogonum, Gymnocalycium buenekeri, Mammillaria albicoma, Mammillaria bocasana, Mammillaria duwei, Mammillaria polythele, Mammillaria fraileana, Thelocactus setispinus, Thelocactus bicolor, Rebutia muscula, Notocactus claviceps, Echinopsis glaucina and others.