Can You revive french Tarragon tree/herb
I got a seedling from a nursery in Ontario, Canada, and I was thinking it was dead (dried up only one thick stem) but I still kept it. Roots look okay but nothing will grow out of it since the last 2 months I have it. I have a light next to it to make sure it has at least 6-8 hours of light and I water it as soon I feel the potting mix is dry. I would like to know if I should keep it or get a new one in summertime.
Try to find out if that brown stick is actually dead. Scrape the outer portion of the stem to see if there is any green under the surface. If it's all brown, the stem is dead. If it's dead, go ahead and cut it off.
Your plant may well be dormant. Why don't you try putting it into a dark, cool room, and water it only enough to keep the soil from getting scratchy dry. Bring it out in the spring, after it's had a winter sleep, water it well and put it into the light. It might will sprout again. This article has more information: https://www.gardeningknowhow.com/edible/herbs/tarragon/growing-french-tarragon.htm