Hey there! I totally get it, there's a wall of fertilizers and it's hard to know what to use. Here's some general guidelines:  

Start with a really quality potting soil. Or if you’re using existing soil, do a test. This will give you an idea of the nutrients available. If you use a quality soil, you won’t likely need to supplement right away.   

When it comes to nutrients for outdoor growing in soil, you’ll need dry nutrients. All those liquid nutrients work well for hydroponics but aren’t the best for soil-grown plants.  

Also, the plant’s needs change depending on the growth stage:  

• Vegetative: A 1-1-1 NPK ratio fertilizer during veg is a good option, especially if you’ve got good soil. But if not, increase the nitrogen ratio up to about a 3-1-1 NPK.  
• Flowering: Reduce the nitrogen. You might go 1-3-2 NPK during the bloom stages.  
  

Gaia Green Organics makes some of the best dry organic nutrients and they're popular among hemp growers. Use the All Purpose blend (4-4-4) during veg and Power Bloom blend (2-8-5) during flowering.