The only soil amendment you really need is a solid all-purpose fertilizer. I personally like the Tomato Tone which also works great for other vegetables as well. It is basically made up of manure and minerals that are mixed together. I prefer to amend my soil with organic products because it takes away the risk that accidentally adding too much will harm my plants. Bone meal and worm castings are my other favorite organic amendments if you are interested in my top three. The others are more situational. Here is my blog post where you can learn in more detail! https://kyriethefoodie.com/how-to-amend-your-soil-for-a-thriving-garden/