If you were to grow a barrel cactus from a seed about how big would it bee in 7-10 weeks? Thank you very much!
They may or may not be germinated ,yet, by that point.If they have, they won't be very big at all. Size is often difficult to describe at that age, as some plants grow a little faster than others at this stage of life. Here is an article that will give you more information on the cactus: https://www.gardeningknowhow.com/ornamental/cacti-succulents/barrel-cactus/barrel-cactus-care.htm