How to Grow a Productive Indoor Herb Garden on Any Windowsill

Why supermarket herbs always die — and what to do instead

Supermarket herb pots are designed to look full on a shelf, not to live. They're typically 20–40 seedlings crammed into a single small pot, each competing for the same water and nutrients. Within two weeks of going home, they collapse from root competition.

Two fixes work: divide the seedlings into separate small pots the day you bring them home, or treat the whole pot as a one-week harvest and start your own herbs from seed in proper individual pots.

Choosing the right windowsill

A south-facing window (in the northern hemisphere) gives 6+ hours of direct sun and is the only orientation where most herbs will thrive without supplemental light. East and west windows can produce decent basil and parsley but rosemary, thyme, oregano, and sage will stretch and weaken.

If you only have north-facing windows, you need a small grow light. A 30 W LED bar mounted 20 cm above the herbs on a 14-hour timer will outperform almost any natural window.

The right pot, the right soil

Use a 15 cm pot per single herb, with drainage holes. Terracotta is better than plastic for Mediterranean herbs because it dries out faster.

Basil, parsley, cilantro, chives, mint: use a standard peat-free houseplant compost. Keep evenly moist.

Rosemary, thyme, oregano, sage, lavender: use a cactus or succulent mix, or amend houseplant compost with 30% horticultural grit or perlite. Let the top half of the pot dry between waterings.

Harvest like a horticulturist

The biggest mistake new herb growers make is letting their basil and mint flower. Once a herb flowers, it diverts energy from leaves to seeds and the flavour collapses. Pinch the top set of leaves weekly, just above a leaf node — this triggers two new branches per cut.

For parsley, cilantro, and chives, harvest from the outside in. Take older outer leaves first and let the centre keep producing.

Never harvest more than one third of the plant in a single session.

The herbs worth growing — and the ones that aren't

Worth it indoors: basil, mint (in its own pot — it will take over), parsley, chives, thyme, oregano, rosemary, sage, chervil.

Hard indoors: cilantro (bolts fast under any heat stress), dill (gets too tall), tarragon (needs a winter chill to thrive next year).

Best replanted regularly: basil, cilantro, parsley. Treat them as 8–12 week crops and re-sow on a rolling schedule.