So, after a long delay I have finally gotten around to seeing what went wrong with my seedlings this year. I came up with 3 possible variables that caused all of my seedlings to fail:
1) Not enough light intensity from the grow light
2) Too cold in the garage and stunted growth
3) Poor soil
After replanting a bunch of basil seeds and pretty much getting the same result again, even though they were in direct sunlight, I figured I needed to test the soil.
I went to one of the big box hardware stores and got 3 other types of soil, allowing me to test 4 total soils:
1) Jiffy All Natural Seed Starter Mix
2) American Country Side Top Soil - My original soil that I used
3) Miracle Grow Nature's Care Potting Mix
4) Miracle Grow Seed Starting Potting Mix
For this test, I used the seeds that I had: Roma Tomato, Cherry Tomato, Jetstar Tomato, and Kale. Each pot had exactly 3 seeds in them, and they were all started at the same time, on 7 June 17.
Here is the experiment layout (from left to right in the pictures):
Pots #1) Jiffy All Natural, with seeds soaked for 1 hour.
Pots #2) American Country Side
Pots #3) Jiffy All Natural
Pots #4) MG Nature's Care
Pots #5) MG Seed Starting Mix
And here are the results as of today:
A closer look at Pots 1 and Pots 2:
A closer look at Pots 3, 4, and 5:
From the results, it is quite clear that the soil I was using this past winter was garbage! Right now, the current winner is MG Nature's Care (the pots in the middle of picture #3), but I am going to wait a little longer before I can conclusively say it is the best seed starting medium. Also, I plan on running this exact same experiment under my grow light to see if I get similar results.