Cilantro doesn’t germinate well, and I’ve had no luck with tarragon.
French tarragon will grow for me but not robustly, and my plants rarely survive the winter here (DC area). Also, it must be propagated vegetatively, not by seed. A few years ago, I discovered "Mexican tarragon" and now I don't bother with French tarragon anymore. It's a plant in the marigold family native to Mexico, but I find the taste of the leaves to be virtually identical to French tarragon. It can be easily grown from seed, and thrives in the hot summers here, unlike French tarragon. The leaf shape is similar to French tarragon, though larger, IOW nothing like the shape of other marigolds. It produces small yellow flowers, though not in profusion. The seeds look just like other marigold seeds. The Mexican Spanish name for it is "
pericón". I have occasionally seen plants for sale here, but I start my own from seed indoors and transplant it outside.
As for basil (which I grow outdoors), it is important to prevent it from going to seed. I cut it back severely periodically, and it produces lots of new leaves before starting to flower again.
I also grow Thai basil from seed. It grows just as easily as Italian basil. The leaves are smaller, and the flowers are very different, producing some beautiful clusters of purple flowers.
In one small area of my vegetable garden, I allow dill to go to seed. I've already had plenty of dill to use this year. I will help scatter the seeds on the ground when the plants die, and the following spring, they germinate without me doing anything. The same thing happens with
epazote, a Mexican herb frequently used in Mexico when cooking beans. I don't even scatter the tiny seeds. It's sort of a weed, but it doesn't get out of control like mint.
One other plant I start from seed is
stevia. The seeds are tiny. It sometimes survives mild winters here, and will also self-seed to a limited degree. I have friends pluck a leaf and I ask them to chew it. Pure sweetness!