What temperature is the heat mat?

Good question, I haven't measured it. I am using VIVOSUN seedling heat mat, it raises temperature 10-20ddgrees over ambient. Currently ambient in my garage is around 60.

Some of them look crowded. Take a small scissors and clip off the extras so that there is 1 seedling per pot.

The seedlings actually look fine to me. But heat mats are for germination rather than long term growing. Could be the roots are too warm.

Plants put as much energy into root growth as they do into top growth. So sometimes there is a lag after they pop the first few true leaves while they throw some roots out. That's why it's important to pot up or at least thin out. Also, you want your lights close down to the seedlings, which becomes problematic as the variance in height becomes more pronounced with time. Keep in mind that peat pods while good for starting seeds are not that great for growing plants. They are low in both nutrients and pH, and easy to overwater. So again, consider potting up soon, especially the peppers and tomatoes. Once you start seeing roots at the edges of the peat pods, that is your cue to pot up. My experience with growing basil from seed is that it is a slow grower, so time will tell. It does like heat, but but maybe not bottom heat, and it's a good idea to let the growing medium dry out between watering to prevent fungal and mildew issues. Air circulation helps there.

Thanks aniajs. I had thought about potting up, but wasn't sure if such small seedlings could take transplant shock. I didn't want to just thin them, I was thinking of dividing them and put in larger pots with real potting soil with some fertilizer.

For now I have picked few samples and just potted-up as is. Will be good learning for me if one of them really do well.

Now that we have some good sunshine outside, from this week I am keeping them out for an hour or so

The basil is not quite as picky, but the peppers and tomato plants need space or they will stunt and delay growth, which can affect your harvest. Transplanting will not hurt them, leaving them two to three plants to a pod will harm them far worse. I tend to start potting mine up when they have 2 sets of true leaves. If you can't stand to thin them down to 1 per pod, you can try to tease them apart when you transplant, keeping in mind that you run the risk of breaking or fatally damaging the plants. But they really do need more space , ideally one plant per container. I use solo cups as my next size up from peat pods, just make sure to poke a few holes in the bottom for drainage. When you repot the tomato plants, you can bury the stem deep (gently break off the seed leaves and repot above where they were, maybe even higher) which encourages more root growth. Tomatoes like to be planted deep every time you replant them. You want thicker, stronger stems that can withstand wind, not leggy plants. Also make sure to take the mesh netting off the outside of the peat pods before you repot.

Daylight is good, read a little about hardening off, but they will still need supplemental light indoors. The more the better up to 16 to 18 hours per day.

Thanks for all the tips. I guess I just had to be little patient and may be little bit more light was needed. All basil plants are thriving now. Holy and Thai basil are slow to grow but they are putting out leaves constantly. Sweet basil has aggressive growth, leaves are quite big now.

I have many of them planted-up, there are few still remaining in the seed starter pod because of lack of space OR area my light source covers, but they are still doing good. I plan to move them out to a south facing window sill may be next week.