You'll find many discussions about this question over on the Vegetable Gardening forum here, assuming you are talking about vegetables. If you mean flowers then each has its own forum with advice on what to feed and how to prepare the soil before transplanting.

Both of the fertilizers you list are liquids. Liquids are normally used after planting to feed the plants throughout the season once they are established.

Vegetable garden beds may be fertilized with any number of things, both organic and synthetic, prior to planting - compost, composted manures, dry granular fertilizers, etc.- things that are dry and mixed in with the soil.

Whether your garden soil actually needs fertilizers or not usually depends on the results of a soil test. You can add fertilizers without a soil test of course but it would just be a guessing game as to what and how much to add and it is easy to add too much.

Check out the gardening forum for your type of plants for more detailed information.

Dave