It is easier and better to use organic stuff to make fertilizer. You should buy all the ingredients separately so it is easy to customize. Things you might require to customize the fertilizer include canola seed meal, bone meal, kelp meal, and lime and one cubic yard of steer manure.
All these items along with your home compost should provide all the nutrition for vegetables to grow in your garden. If you follow the procedure everything will grow just fine with about one gallon of the mix on a bed three meters by three meters.
Fertilizers contain nitrogen, phosphorus, and potassium, or NPK, which are expressed numerically on labels, such as 5-15-1. Each number represents the percentage of the total mix by weight.
The individual items procured by you would have the following composition for a customized fertilizer for your garden;
Canola meal -Slow release nitrogen and phosphorus with a trace of potassium, roughly 6-2-1.
Bone meal -Moderately slow release nitrogen and phosphorus for root development with the bonus of calcium, roughly 3-15-0.
Kelp meal: Relatively quick to release nitrogen but higher in potassium than seed meals and contains lots of trace minerals, about 1-1-2.
Compost: Improves aeration and moisture retention, about 1-1-1.
Blood meal: I don’t put it in my general purpose mix, but it can provide a quick hit of nitrogen when slow-release isn’t doing the job, 14-0-0.
Basic customized garden fertilizer to grow vegetables will be mixed up in the combination and specified quantity of 10 parts canola seed meal +1 part lime + 1 part bone meal + 1 part kelp meal.
It is good to keep all the above the components of your fertilizer separate so that you can mix on the fly for each bed of vegetables you plant.
If you are growing potatoes in your garden remember not to include lime in your customized fertilizer. Similarly, tomatoes like phosphorus for fruit growth but prefer slow-release nitrogen.