How to Grow Herbs Indoors: A Realistic UK Windowsill Guide

Individual pots make it easier to give mint, basil and Mediterranean herbs the different conditions they need.

You can grow useful herbs on a UK windowsill without a specialist indoor-garden system, but “put any herb by a window and water weekly” is not a reliable method. Light falls sharply away from glass, winter growth slows, and herbs differ in their tolerance of warmth, shade and wet compost.

Start with one or two herbs you actually cook with. A £3 pot that produces regular harvests is better value than six struggling plants bought for display.

Choose the best window you have

Position	Likely conditions	Good candidates	Watch for
South or south-west	Brightest and warmest	Basil in warmth; thyme and rosemary with strong light	Scorch behind glass, rapid drying and cold night glass
East	Gentle morning sun	Parsley, chives, coriander and mint	Growth leaning toward the pane
West	Afternoon light and summer heat	Many herbs if watered appropriately	Overheating and dry compost
North	Lower light, especially in winter	Mint, parsley or chives may cope for a time	Weak, stretched growth; manage expectations

Place pots close to the window without pressing foliage against cold glass. Turn them a quarter turn every few days. In winter, harvest less and accept slower growth. A grow light is optional, not “special equipment” you must buy; if you use one, select a reputable purpose-made product and follow its electrical and distance instructions.

What each common herb actually needs

Herb	Light and temperature	Water	Harvest reality
Basil	Very bright, warm and frost-free	Evenly moist, never standing in water	Pinch shoot tips above a leaf pair; tender and often short-lived in a UK winter
Mint	Bright light to partial shade; cooler is acceptable	Moist but drained	Harvest tips often; keep in its own pot because it spreads
Parsley	Well-lit window; tolerates some shade	Moist, not waterlogged	Take outer stems; germination from seed can be slow
Coriander	Bright and relatively cool	Keep evenly moist	Best sown little and often; indoor pots are usually short-term and may bolt
Chives	Bright light	Water when the surface begins to dry	Cut leaves above the base; allow regrowth
Thyme/rosemary	Strong light and good airflow	Let the surface dry somewhat; never leave waterlogged	Harvest modestly; wet roots and weak winter light are common failures

Pots and compost: keep it simple

• Use a clean pot with drainage holes and a saucer. Decorative cachepots are fine only if you empty collected water.
• Use fresh peat-free multipurpose compost suitable for containers. Do not bring garden soil indoors: it compacts in pots and may introduce pests, weed seeds or pathogens.
• Give Mediterranean herbs particularly free-draining conditions; follow the compost and plant label rather than improvising with building sand.
• Keep species in separate pots until you understand their watering needs. Mint and basil are poor long-term companions for rosemary and thyme.
• Wash reused pots and inspect second-hand containers for cracks and contamination.

Three low-cost ways to start

1. Divide a supermarket herb carefully

Many supermarket pots contain crowded seedlings intended for quick use. Water first, ease the root ball apart into two or three small groups and pot them separately. This can extend basil, parsley, chive or mint plants, but it is not guaranteed: plants may already be stressed and coriander dislikes root disturbance.

2. Sow a small succession

Seed is economical when you want repeated coriander, basil or parsley. Use labelled pots and sow only part of the packet. Follow the packet depth and temperature; do not assume every herb germinates within the same three-to-six-week window.

3. Buy one healthy nursery plant

For slower perennial herbs such as rosemary or thyme, a compact healthy plant can be better value than waiting from seed. Check leaf undersides and stem joints for webbing, scale, sticky residue or clusters of insects before bringing it into the kitchen.

A watering method that responds to the plant

1. Lift the pot and feel its weight. Check the compost with a fingertip rather than watering by calendar.
2. Water over a sink until the compost is evenly moistened and excess drains.
3. Return it to the saucer only after drainage; empty any later collection.
4. Recheck sooner in hot sun and later in cool, dark weather. Small supermarket pots can change quickly.
5. If compost stays wet, smells sour or attracts fungus gnats, reduce watering and inspect drainage and roots.

Safety first: Never place pots where they can fall onto a hob, kettle or person. Keep foliage and watering cans away from sockets and appliances. Identify a plant confidently before eating it, use only edible herbs raised without unsuitable chemicals, and wash leaves before use.

Diagnose problems instead of guessing

Symptom	Likely possibilities	First response
Long pale stems	Insufficient light or overcrowding	Move closer to safe bright light, rotate and thin appropriately
Yellow lower leaves	Overwatering, poor drainage, age or nutrient shortage	Check roots and compost moisture before feeding
Crisp edges	Dry compost, hot glass or low humidity	Move slightly back from intense glass and water appropriately
White powder	Powdery mildew encouraged by crowding/stale air	Isolate, remove badly affected growth and improve spacing
Sticky leaves/webbing	Aphids, scale or spider mites	Isolate, inspect closely and use an edible-crop-suitable control
Sudden collapse	Cold damage, severe drought or root rot	Check temperature and roots; restart if the crown has failed

Harvest for regrowth

Use clean scissors. Take a little from several stems rather than stripping the plant. Pinch basil tips above a leaf pair; cut chives above the base; take parsley’s outer stems; pick mint tips regularly. Avoid removing more than roughly a third of a small stressed plant at once. Flowers are not automatically a failure, but basil or coriander flavour and leaf production may change as plants bolt.

A four-week windowsill plan

1. Day 1: choose two herbs, inspect them and pot into drained containers if needed. Label each.
2. Week 1: record window direction, watering and visible growth; rotate pots.
3. Week 2: make the first light harvest only from actively growing plants.
4. Week 3: inspect leaf undersides and adjust spacing; sow a small second coriander or basil pot if useful.
5. Week 4: keep the successful herb, relocate the struggling one and resist buying more until you know why it struggled.

BudgetNest note: If you are also rescuing decorative plants, use the houseplant rescue guide and the beginner indoor-plant guide. Their care advice should not replace edible-herb hygiene.

Useful UK growing guidance

• RHS: growing and harvesting herbs
• RHS: growing herbs in containers
• RHS: coriander

A restrained FAQ

Do herbs need direct sun all day?

No single rule fits all herbs. Basil, rosemary and thyme want strong light; parsley and mint tolerate more shade. UK winter windows are often limiting even when summer growth was good.

Can I use garden soil in a windowsill pot?

Use container compost instead. Garden soil commonly compacts, drains unpredictably indoors and may bring unwanted organisms into the home.

Why does supermarket basil die?

It is often crowded, tender, chilled during transport or moved into low winter light. Divide only healthy plants, keep them warm and bright, and regard winter basil as a short-term crop if conditions are poor.