|Spring is in the air and more and more cacti start flowering. Depending on local weather conditions and cactus species in the collection, more or less cacti are flowering. Except for mammillarias, this month gymnocalycium, echinocereus, notocactus and others are starting to flower.
April and May are months with frequent rainfalls generally here in Greece (one year we had also snow in April!!), and this is probably the most important point that someone should pay attention to: the quantity of water in the cactus containers. So, two things must be taken care of, first, cacti that stay outside (and they should stay out in the fresh air) should be protected from the rain. The second point has to do with our participation in the water that cacti get. This month a lot of cacti flower, develop buds and start to grow again, but cacti should not be water too generously, at least not at the first time of watering after winter. Some cacti might take too much water and their skin could develop cracks or, worse, they could rot.
One useful rule someone could follow is to start watering with small quantities of water those cacti that show growing signs (e.g. new spines), cacti that prepare flower buds and cacti that flower. Just because some days might be warmer does not mean that all cacti should be watered, especially not those that have not yet started to grow.
Cacti of the genus notocactus need this time some more water, especially when you see new spines and developing buds. The same is true for mammillarias that start to flower. Remember: less water does not harm cacti, too much water can destroy them. So, for cacti that flower, are in a good draining soil, at a spot with enough time of sunlight and under overall good weather conditions and temperatures, watering can be done every 7 to 10 days. The above can be adapted to different conditions, e.g. soil with less good drainage, less sunlight, colder weather etc.
This month feeding can be started. Like with watering (after all, fertilizer is usually given during watering or with water), it is useful to feed cacti that flower, prepare flower buds and not yet the ones that still do not show signs of growth. The fertilizer used should be a special cactus fertilizer, but when it is difficult to find a special one, a regular plant fertilizer could be used. Usually, fertilizers with low nitrogen are preparates that are labeled "for flowering plants". After repotting of the cacti with fresh soil, there is no need to fertilize since most commercial cactus soil mixes already contain fertilizer.
This month cacti can be repotted: older ones that outgrew their pots or the new purchased cacti, who, usualy are sold in very small pots. Cacti that are flowering can stay in their pots and be repotted after they stop flowering, except for some special cases (e.g. not enough soil in the pot with exposed roots or cacti that have become too large for the current pot, making it difficult to water the plant and to check the humidity of the soil). After repotting, the plant should stay dry and not watered for a few days.
It is very important that cacti are in a very bright location, but the sun starts to burn gradually more than before and cacti that stayed in a less bright location until now could develop burnmarks. Heavyspined cacti are less sensitive to burnmarks than lightspined cacti.
Cacti flowering this time of the year:
mammillaria carmenae, mammillaria rekoi leptacantha, mammillaria candida, mammillaria backebergiana, mammillaria uncinata, mammillaria zeilmanianna, mammillaria bombycina, mammillaria bocasana, mammillaria spinosissima (cv un pico), mammillaria microhelia και άλλες mammillaria, gymnocalycium, echinofossulocactus, echinocereus and others.