what fertilizer ratio is best to use for indoor cacti

[allygracebz]

Mature and young cacti, medium light. I have 15-30-15, would that work? And dilution recommendations? Thanks!

[Saxicola]

I'd fertilize at half strength about once per month in the growing season. Probably not at all in the winter unless they are still actively growing. If you grew them outdoors I'd probably tell you full strength every 2-3 weeks, but indoors the conditions aren't as good so they grow slower.