|May is the month with the most flowers and the most visible growing signs on cacti. So, most of the time is spent on observing the plants and admire their beautiful flowers and their new spines...
Almost all cacti are watered normally during this month. Except for days when the weather is rainy and cold for extended time, cacti are watered every 7 or 10 days. This period is a suggestion and, of course, a very usefull tip is to water only when the soil has dryed out completely from the last watering.
This month rainfall is also very frequent in Thessaloniki, so cacti should be protected from heavy rainfalls.
Cacti may be watered with fertilizer one or two times during this month. This is especially important for cacti that are flowering and for those who have been repottet last year or longer back. If no special cactus fertilizer can be found, someone could use a regular plant fertilizer or a fertilizer that is labeled "for flowering plants".
This month repotting of cacti can be done but, usually, I avoid repotting of plants that are currently flowering. Except cases like: cacti affected by some pest or very large cacti in very small pots which makes it difficult to water the plant and/or to check the humidity of the soil.
This is also the best time to take cuttings or offsets of cacti and put them in an individual pot. In both cases, repotting or planting offsets, watering should be done after approximately one week.
Cacti could be affected by various pests this time. So it is essential to check for possible infestations (bugs etc.) in order to treat them and prevent the spread of the pest to the rest of the collection. This month almost all cacti are showing growing signs. The absence of growing signs in a plant that usually grows this time of the year could be an indication of root mealy bugs (usually, the plant looks shriveled, like most cacti in winter, but after a few times of watering the appearance of the plant stays the same). So it is important to check the roots in such cases, because the development of the plant could stay behind if the pest is left untreated.
Most cacti, especially those that are flowering need to be in a very bright location and a lot of them need direct sun exposure, at least for some hours during the day.
Cacti flowering this month
mammillaria spinosissima, mammillaria backebergiana, mammillaria uncinata, mammillaria spinosissima, mammillaria magnimamma, mammillaria prolifera, mammillaria matudae, mammillaria melanocentra, mammillaria karwinksiana, mammillaria duwei, mammillaria bocasana, mammillaria zeilmanniana and other mammillarias, notocactus (parodia) schlosseri, notocactus uebelmannianus, notocactus fuscus and other notocacti, gymnocalycium, echinofossulocactus, echinocereus, rebutia, hatiora and others.