Minerals in the soil itself, not necessarily vitamins.
The source of vitamins they need is plenty of sun lol Like sun is good for us a source of vitamin D.
When it comes to watering the plant, don't over do it as much, unless you're keeping it outside, keep an eye out for your plant daily to make sure it's growing c;
I'm pretty sure the vitamins plants need are from the sun (helping with photosynthesis). But plants need minerals from the soil, and water to grow.
Vegetables do not need vitamins.
The plants need minerals (that come from the soil), water and sunlight.