|The very hot days are gradually over and while heading to autumn flowers are fewer. This month is the first official autumn month but the good weather can last for some days, sometimes for the whole month. This means that some cacti gradually stop their development but some others are still growing.
While good weather persists watering can be regular. One point that should be checked is the condition of the cacti regarding growing signs. I have noticed, for example, that this time of the year columnar cacti continue to grow. This is something that starts from the previous month and continues during this month too. These cacti are watered regularly, approximately once a week. Of course, the usual "watering-signs" must be taken into account: pot size, plant size, soil and temperature, so that watering frequency is adjusted accordingly. This month, with the somewhat lower temperatures, the soil is drying slower.
Finally, in order to prevent "disaster", it is best to protect cacti from rain, since this month it is usual to have at least some rain here in Greece, but in some cases, it is not only rain but heavy storms.
There is no reason to move cacti from their summer location (except for the case that this location was temporary and with no sun). Cacti love sun and, since days become shorter and the the days get cooler, they should stay in a sunny spot so they can gradually harden off and prepare for the colder winter days.
Temperature coud fall alot this month, especially during nights, compared to summer. But usually on sunny days, temperature is climbing again, during the day. This condition is especially favorable to cacti and it does not mean that they should be protected or brought inside. Except cacti that are cold sensitive, like melocacti and discocacti. During the nights, when temperature is below 15o C, these cacti can be brought inside. But, during the day, when temperature climbs again it is best to place them again outside, where they have more light.
So, if someone intends to leave his/her cacti outside during winter, this and the next months are the best months to prepare cacti so that they can gradually get accustomed to the lower temperatures.
This month, and maybe the next month too, is the best to treat cacti for some pest they might have, because it is a transitional month with a lot of warm days and not so much humidity like the following months. Because usually treatment of plant pests and diseases is done with either spraying or watering, this month gives the opportunity to do this with a lower risk of rot.
Furthermore, the treatment is best done now, before cacti are moved to a closed space with less ventilation. The bugs could stay active for a lot of time and continue to multiply themselves infecting other plants too.
So, during the first watering of this month I check carefully every plant (especially between ribs, close to dryed up flowers, in the root neck where the cactus base contacts the soil etc.). If some pest is detected, the options are two:
The first option is to quarantine (put away from the healthy plants) infected cacti and treat them with some pesticide (depending on type of pest).
The second option is to treat all cacti. Therapeutical for the sick ones and preventative for the rest. This option is sometimes meaningful because it could be that we have not noticed some pest or bug eggs on some plant. This could result in other cacti being affected too.
Cacti flowering during this month:
Echinopsis, Gymnocalycium baldianum, som Mammillarias, Thelocactus setispinus, Parodia laui, Parodia formosa, Rebutia neocumingii and others