Growing basil on a windowsill
Basil is the herb most people buy and most people throw away. That is rarely your fault: a supermarket pot holds fifty seedlings competing for the same drop of water. Sow it yourself and basil becomes one of the easiest plants for a warm windowsill.
At a glance
- Light
- 6+ hours of direct light, ideally south-facing
- Pot depth
- Pot at least 15 cm deep
- Sowing
- March to June, indoors on the windowsill
- Harvest
- 6 to 8 weeks after sowing, then continuously
- Water
- Keep lightly moist, never waterlogged
- Level
- Easy
Sowing
Fill a pot with compost, firm it lightly and scatter the seeds well apart — five to eight seeds in a fifteen-centimetre pot is plenty. Cover with half a centimetre of compost and moisten the surface with a spray bottle rather than a watering can, which would wash the seeds away.
Basil germinates on warmth, not light: at 20 to 25°C the first seed leaves appear within five to ten days. On a cold windowsill in March it can take twice as long, so keep the pot off the glass when it is freezing outside.
Care
Water from below: stand the pot in a dish of water for fifteen minutes, then let it drain completely. Basil tolerates dry compost far better than a soggy base, where the roots rot within days.
Pinch out the top as soon as the plant has six true leaves. It feels wasteful, but it is exactly what turns a spindly seedling into a bush: every time you remove the tip, the plant branches in two at that point.
Harvesting
Never pick individual leaves from the bottom. Cut whole stems just above a pair of leaves — two new shoots grow from there, keeping the plant compact instead of bare and woody.
Spotted flower buds? Remove them immediately. Once basil flowers, leaf production stops and the leaves turn bitter.
Common mistakes
Overwatering is the number one killer, closely followed by a pot with no drainage holes. Both produce the same picture: limp leaves you mistake for thirst, so you water even more.
And that supermarket pot is not a plant, it is a bunch. To rescue it, split the root ball into three and pot each part separately.
Frequently asked questions
Why does my supermarket basil always die?
Because there are dozens of seedlings in one pot, grown for sale rather than longevity. They have too little root space and dry out fast. Split the root ball into three or four parts, pot them separately, and it will survive.
Can basil grow indoors all year round?
In winter only with supplementary light. From November to February there is too little daylight in northern Europe; without a grow light the plant turns long and floppy. Sowing fresh in March is easier.
How many basil plants do I need?
Two or three pots cover weekly cooking. For pesto, count on about six plants per batch.
Updated on 2026-08-25
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