I'd like to customize the fertilizer to the needs of what I grow, which is basically any kind of vegetable.

I've done some research, and found out this......

Fruiting plants (eggplants, peppers, tomatoes, melons, squash) require a fertilizer high in potassium and phosphorus

Leafy green stuff (lettuce, spinach, chard, etc.) require a high-nitrogen fertilizer

Root veggies(carrots, beets, turnips, etc.) require a fertilizer high in potassium and fertilizer

I've found some fertilizer recipes online, I'm just wondering if they're valid? By this I mean, reliable, and will meet the needs of the plant they're being used with.

Here are the recipes:

Recipe #1 (designed specifically for tomatoes)

16 cups seed meal (most common ones I've found are cotton seed meal)

2 cups dolomitic lime
2 cups agricultural lime
4 cups bone meal
4 cups kelp meal

Basic Organic Fertilizer Mix:

~~ For use at planting time or side dressing for all types of plants ~~

3 parts blood or fishmeal
3 parts steamed bone meal
1 part kelp meal
1 and 1/2 parts Sul-Po-Mag (a brand name for a sulfur, potassium, and magnesium source, but you can substitute any such mixture.)

The following specially formulated mixes are fast acting and work well when used at planting time and as side dressings. Although these balanced mixes will generally give desired results, soils do vary. You can experiment and find what works best for your soil.

Generally, the fertilizers are applied at the rate of: 1/2 cup per transplant, or 5 pounds per 100 square feet or 100 row feet.

High Nitrogen Mix:

~~ For plants that are grown with the leaf or follar structure as the edible part ~~

4 parts blood meal
2 parts cottonseed meal
1 part steamed bone meal
1/2 part Sul-Po-Mag (a brand name source for sulfur, potassium, and magnesium)
1/2 part kelp meal

High Potassium Mix:

~~ For crops that are grown with the root or tuber as the edible part ~~

2 parts cottonseed meal
2 and 1/2 parts Sul-Po-Mag
1 and 1/2 parts steamed bone meal
1 part greensand
1 part kelp meal

High Phosphorous Mix:

~~ For crops that are grown for the fruit or seed as the edible part ~~

4 parts steamed bone meal
1 part fish meal
1 part meat and bone meal
1 part soft phosphate
1/2 part Sul-Po-Mag
1/2 part kelp meal

For the tomato fertilizer, could I also use it for eggplants and bell peppers, since I've been told they have similar nutritional needs (with fertilizing) as tomatoes.

As a result, my root vegetables didn't grow well at all; I got good leafy tops, but skinny spindly root portions that weren't even edible. Also with my fruiting crops, such as squash, they really didn't do well either, and I'm just guessing that part of it had to do with not being adequately fertilized, and not getting the nutrients they need too.

I didn't overfertilize, all I did was add the amount of fertilizer that the recipe I used specified. I didn't fertilize later in the season.

I don't like to use just a generic fertilizer for all plants, because different vegetables have different needs with the nutrients they need and in what amounts they need those nutrients.

Not to be rude, but although the advice offered was helpful, and thank you for it and taking time to post it, it didn't answer my original question.

That was if the fertilizer recipes provided are reliable.

Below is the soil mixture I make up and use for container gardening. With the exception of the micro nutrients (which I didn't add because I couldn't find) I followed the recipe below exactly:

2-3 cu ft pine bark fines
5 gallons peat
5 gallons perlite
2 cups dolomitic (garden) lime (or gypsum in some cases)
2 cups CRF (if preferred)
1/2 cup micro-nutrient powder (or other source of the minors - provided in some fertilizers)

The link above is from amazon; you can buy cottonseed meal from there. You'll have to manually copy and paste it
into your browser, click 'send' then wait for the site
to redirect you via opening a new page.