1. You’re drowning them.
Herbs love water but don’t want to swim in it, so make sure your pots offer sufficient drainage. Look for pots that have a hole at the bottom that will let excess water seep out — and pair them with a saucer so you don’t have a mess.
2. You’re forgetting to prune.
Pinch off flowers and trim your plant regularly to keep it from getting top-heavy. Different herbs do require more or less pruning (basil requires a lot; parsley requires very little), so do your research. Gardening Know How offers simple directions for every herb.
3. You’re not giving the soil a nutrient boost.
Don’t rely on the potting soil your plant comes in. Feed your actively growing herbs with liquid fertilizer or organic fish emulsion once a week (find them at the gardening store), recommends the National Gardening Association (NGA). And if you compost, make sure to mix some into the soil.
4. You’re being a little too ambitious.
Growing herbs from seed isn’t easy if you’re new to gardening. There’s no shame in beginning with a starter plant from the gardening store.
5. You’re not researching your plants.
Not every plant should be treated the same: Parsley requires misting or high humidity; chives shouldn’t be over-fertilized.
Read more: https://www.goodhousekeeping.com/home/gardening/a32223/indoor-herb-garden-mistakes/