How to fertilize the cactus?

The best fertilizer for your indoor cactus is a balanced one, to ensure that all the nutrients needed are provided. The ratios of nitrogen, potassium and phosphorus will depend on what you want the plant to achieve: growth (higher nitrogen ratio), more flowering (higher potassium ratio) or greater disease resistance (higher phosphorus ratio). Use liquid fertilizer, it should be at a quarter to half strength, as cacti are not heavy feeders; apply during watering when it’s the growing season. If the cactus is receiving little light indoors, do not give it too much fertilizer or it will produce weak growth.