easy · windowsill
How to grow basil
The fastest way to prove to yourself that growing food works. From seed to first harvest in about six weeks on a sunny windowsill.
Ocimum basilicum · Lamiaceae
Why bother
Supermarket basil is grown fast under glass and sold in an overcrowded pot, which is why it collapses within a week. One plant grown properly will crop for a whole summer.
What it needs
- Light
- At least 6 hours of direct sun. A south-facing windowsill is ideal.
- Water
- Keep the compost lightly moist but never waterlogged. Water in the morning, at the base, not over the leaves.
- Soil
- Free-draining peat-free multipurpose compost. Drainage holes are essential.
- Temperature
- 18-25C. Basil hates cold — it will blacken below about 10C.
- Container
- One plant per 15cm pot, or three across a 30cm trough.
- Time to harvest
- 5-6 weeks from sowing to first picking.
Step by step
Day 0
Sow the seed
Fill a pot with damp compost, scatter seed thinly on top, and cover with about 5mm of compost. Basil needs warmth to germinate, not depth.
Days 1-7
Keep it warm and covered
Cover the pot with a clear bag or propagator lid and keep it somewhere around 20C. Remove the cover as soon as seedlings appear.
Week 2
Thin the seedlings
Once each seedling has two true leaves, keep the strongest and remove the rest. Crowded basil never thrives — this step is the one most people skip.
Week 3-4
Pinch the growing tip
When the plant has three pairs of leaves, pinch out the very top pair. This forces it to branch sideways instead of growing into a single stalk.
Week 6 onward
Harvest from the top
Always pick from the top down, taking whole stem tips just above a pair of leaves. Never strip the lower leaves — those are the plant's engine.
What usually goes wrong
Leggy stems with big gaps between leaves
Cause: Not enough light — the plant is stretching toward the window.
Fix: Move to the brightest spot you have and pinch out the growing tips to force bushier growth.
Leaves yellowing from the bottom up
Cause: Overwatering. Basil roots rot quickly in sodden compost.
Fix: Let the top 2cm dry out before watering again, and empty any saucer after watering.
Plant bolts — sends up a flower spike
Cause: Heat stress, or simply the plant reaching maturity.
Fix: Pinch flower spikes off as they appear. Leaf flavour drops sharply once it flowers.
Grows well beside
Tomato, Pepper
Before you eat anything you grow: be certain of the identification. This guide describes basil specifically — it is not a way to confirm that an unknown plant is safe. Never eat a plant on the strength of an app alone.