At a glance
A windowsill herb garden is one of the most practical additions to any UK kitchen. Fresh herbs used within minutes of picking have a flavour supermarket equivalents cannot match, and having them immediately to hand means you actually use them rather than buying a packet, using one sprig, and watching the rest wilt in the fridge. A south-facing windowsill in reasonable light can support four or five herbs in steady production year-round – enough to supply most households with everything they need for everyday cooking.
The gap between herbs that thrive indoors and those that struggle is almost entirely down to light. Most culinary herbs are Mediterranean in origin and evolved in intense sunlight. The light available on even a south-facing UK windowsill in winter is considerably less than they receive in their native habitat, which limits growth and makes management important. Understanding which herbs genuinely suit indoor life and which are better grown outdoors makes the difference between a productive windowsill and a graveyard of wilted pots. For herbs that perform better with more root space and outdoor conditions, our guide to growing herbs in a small space covers raised bed and container growing outdoors.
Light – the most important factor
Indoor herbs need as much light as possible. A south-facing windowsill is the best position in any UK home – it provides direct sun for the most hours of the day and gives herbs the best chance of growing vigorously rather than slowly and weakly. East or west-facing windowsills produce acceptable results for most herbs except basil, which really needs maximum sun. North-facing windowsills are only suitable for chives and mint – all other herbs will grow so slowly and weakly in north-facing light that they are not worth attempting.
In winter, even south-facing windowsills in the UK provide only three to four hours of direct sun on the clearest days. Most herbs slow down significantly in winter – this is normal and expected. Reduce watering to match reduced growth, do not feed, and accept slower harvests. Growth picks up noticeably as day length increases from February onwards.
Best herbs for indoor growing
Basil is the most popular indoor herb and produces well on a sunny south-facing windowsill from May to October. It needs warmth as well as light – a cold kitchen windowsill in winter is not suitable for basil. Chives are the most reliable indoor herb year-round, growing in lower light than most and recovering quickly after cutting. Mint grows vigorously indoors but needs to be kept in its own pot – its spreading root system invades and suppresses neighbouring herbs rapidly.
Parsley is productive indoors in good light and is useful year-round. It takes longer to establish than the others – a pot started in September from fresh seed will be productive by December and continue through winter. Coriander can be grown indoors but bolts rapidly to seed in warm conditions – grow it on a cool windowsill and sow successionally every six weeks for a continuous supply rather than trying to keep one plant going for months.
Rescuing supermarket herbs
Supermarket potted herbs are grown intensively with many seedlings crammed into a small pot for rapid sale. They are not designed to last – the growing conditions in a store produce soft, tender growth that struggles to survive in a home. However, with the right approach, a supermarket herb pot can be divided and grown on into several productive plants.
Remove the plant from its pot and gently tease apart the root ball into three or four clumps of several plants each. Pot each clump separately into a 10-12cm pot with fresh multipurpose compost and water in. Cut each clump back by about a third to reduce the leaf area the roots need to support. Place on the sunniest available windowsill. Within two to three weeks the plants begin producing new growth and establish as properly rooted individual plants that will last for months rather than days.
Pots, compost and drainage
Drainage is the single most important physical requirement for indoor herbs. A pot without drainage holes, or a pot sitting in a saucer of water, kills herbs faster than any other mistake. Always use pots with drainage holes and empty saucers after watering. Terracotta pots are better than plastic for most herbs – they are porous and allow the compost to breathe, reducing the risk of waterlogging that causes root rot.
Use a multipurpose compost for most herbs. For Mediterranean herbs like rosemary, thyme and sage, mix standard compost 50/50 with perlite or horticultural grit to improve drainage – these plants are adapted to poor, free-draining soils and standard compost holds too much moisture for them indoors. Repot into slightly larger containers each spring as roots fill the pot, using fresh compost to replenish nutrients.
Watering correctly
Overwatering is the most common cause of indoor herb failure. The correct approach is to water thoroughly when the compost feels dry 1-2cm below the surface, then allow it to drain fully before replacing in the saucer. In winter, this may mean watering only once a week or even less. Basil is the exception – it likes consistently moist (not wet) compost and wilts quickly if it dries out. Check basil daily in summer, every other day in cooler months.
Always use room temperature water for indoor herbs – cold water from the tap can shock roots and cause leaf drop on basil in particular. If your tap water is very hard, occasionally watering with cooled boiled water or collected rainwater removes the mineral build-up that appears as white crust on the compost surface over time.
How to harvest for more growth
The correct harvesting technique dramatically extends the productive life of indoor herbs. For leafy herbs like basil, mint and parsley, always cut stems back to just above a leaf node rather than stripping individual leaves – this stimulates branching and produces a bushier, more productive plant. Never remove more than a third of the plant at one harvest. For chives, cut the leaves down to 2-3cm above compost level and the plant regrows from the base within two weeks.
Prevent herbs from flowering where possible – once a plant flowers it puts energy into seed production rather than leaf growth, and leaf flavour often deteriorates. Pinch out any flower buds that appear on basil immediately. Allow coriander to flower if you want to harvest the seeds; otherwise pinch flower stems out regularly to prolong the leafy growth stage.
Rotate herbs a quarter turn every few days. Herbs grown on a windowsill lean toward the glass over time, producing lopsided, uneven plants. A quarter turn every two to three days keeps growth balanced and ensures all sides of the plant receive equal light. This simple habit produces fuller, more productive plants with no extra effort.
Common problems
Yellowing leaves on basil indicate overwatering, cold temperatures or insufficient light – check all three before deciding on a remedy. Basil kept below 15°C will yellow and drop leaves regardless of other conditions. Leggy, pale growth on any herb indicates insufficient light – move to a brighter position immediately. Whitefly can establish on indoor herbs, particularly basil; sticky yellow traps hung near the plants catch adults and breaking the breeding cycle, combined with removing heavily infested leaves, usually clears the problem without chemical treatment.
Mint confined to a pot eventually exhausts the compost and becomes pot-bound – the leaves become small and the growth weak. Repot in spring into fresh compost and cut hard back to 5cm to stimulate a flush of vigorous new growth. Divide the root ball at this point if the plant has become congested and pot the divisions separately for more plants.
