Will a potted cactus survive just with water, or should I also give it plant food?
In short, yes you do although not very often. 1 feed 3 times a year should do the trick.
Use a fertilizer with 4% Nitrogen, 7% Phosphorous and 7% Potassium. These details should be clearly shown on the box or bottle.
All plants require nutrients of some sort or another to survive and they have all sorts of ingenious ways of getting these nutrients in nature. However, when we keep them in an artificial environment we have to look after them and give them what they need.
Another thing to remember with cacti is never to place them in direct sunshine as they suffer from sunburn.
Answered by Green Shoots Landscaping from United Kingdom, Crieff, in June 2010.
Green Shoots Landscaping is a provider of Landscaping and garden maintenance services