Cacti in the UK
I’m hoping you could give me some advice, I live in the UK and bought an Echinocactus grusonii a few months ago. The guy told me to water once a fortnight and add Baby Bio plant foot or tomato feed in each alternate. The first few times I watered it it was fine but this time I think I’ve killed it. Within a day of feeding the spines have started to die around the base, it’s got dead looking patches and darker green patches that look like water marks. It doesn’t feel squishy but the bottom looks like it’s shrinking in on itself.
Have I broken it? Can it be saved?
Thanks in advance
It’s hard to tell for sure from the photo, but it is not looking great. I think there may be 2 different pests, but again it’s hard to tell from the photos. The base looks like it has started to rot, in which case it is too late to save it. But if it is firm, maybe I am misreading it. If it is firm, you can try to use a systemic fungicide, and spray the rest with an organic pesticide. Not sure what’s available in the UK, but we use Bonide Infuse and Monterey Take Down Garden Spray.
In general we would suggest watering every 4 weeks (every 2 fortnights?) for the cooler parts of the year, and every 2-3 weeks when it is hot and sunny. Do not fertilize regularly with any tomato fertilizer – it’s too strong for cacti. Use an organic low strength granular all-purpose (like Down to Earth All Purpose) and use it at lower strength than recommended. Use only twice in a year – spring and mid-summer. Let the plant grow slow and it will be healthier.