Q.What Are The Best Fertilizer Types?
Outdoor flowers, northern California valley.

Certified GKH Gardening Expert
An all purpose balanced fertilizer like 10-10-10 in a slow release form is often recommended. You can also look up certain plant varieties on our website for specific fertilization tips. A soil test is always the best bet because it tells you exactly what nutrients may be lacking. Your local cooperative extension can help with a soil test or you can buy kits.
Here is general info on when to fertilize:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/best-times-to-apply-fertilizer.htm