A good rule of thumb is to wait until your seedling is about 3-inches (7. 62 cm) high. You should also make sure that your seedling is healthy. Check for yellow or curling leaves, or any other sign of weakness. Transplant only your healthy plants. You can also check to make sure the herb seedlings have formed a ball of roots, but this can be difficult to do without removing the plant from its pot or pellet.
You can also add rocks to the bottom of your pot to help drain the water. Good drainage is essential for many herbs, such as rosemary and sage. Try to stick to pots between 6”-8” for single plants and 10” and up for multiples. Make sure that your pots have drainage holes.
If you are unsure of how many seedlings to put in each pot, a common rule to remember is that a pot that is 8 inches or smaller should have only one plant, and one that is 10 inches or larger can have multiple plants.
