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Grow lights for kitchen herbs

Supermarket basil collapses on a dark worktop because the kitchen is not the greenhouse it was grown in. A light can keep a pot of herbs useful through winter. It will not turn a north-facing counter into July.

What the herbs are asking for

Basil is the demanding one. An RHS houseplant profile for basil says it wants a bright spot, at least about six hours of sun, and a grow light where that sun is missing. The same profile gives a temperature band of roughly 21–27 °C by day and not below 10 °C at night, compost that stays moist rather than soggy, and a note to pinch flowers so the plant keeps making leaves. That profile is on the RHS Urban Show houseplant notes.

Parsley is more forgiving of a cooler sill and a slightly shorter day. It still stalls in a cupboard.

Chilli seedlings want strong light or they stretch into threads before the first true leaves. Once they are sturdy plants in summer they can live outside or in a porch. Under a lamp they are a seedling job, which overlaps with propagation lights.

Hours on a counter

For herbs, 12–16 hours of light, then a dark period, is the indoor pattern used in the shelf tool. If the pot sits in a bright south or west window, the lamp is a winter top-up and can run for less than 16 hours. If the counter never sees the sky, the lamp is the day, and you are nearer 14–16 hours. The reasoning, including the RHS 16-hour example for a dedicated setup, is in hours and a dark period.

A timer matters more in a kitchen than in a spare room, because the light is easy to leave on while you cook and easy to forget after. One timer. Not a second timer behind a lamp that already has one.

Splash, steam and the lead

Kettles, washing-up and a wiped worktop all throw water. A grow bar is not a kitchen under-cupboard light unless the listing says it can live in that splash. Keep the fitting, the driver and the plug back from the sink. Water the pot in the sink and let it drain before it goes back under the lamp. Do not mist the lamp.

Steam from a hob is a separate problem. A lamp directly above a frying pan collects grease and sees heat it was not rated for. Put the herbs to one side.

The format is usually a short bar under a shelf, or a bulb in an open fitting if you only have one pot. Closed shades are a poor idea: see E27 and B22. A clip gooseneck is enough for a single basil pot and too small for a row of them. Formats are compared in bulb, bar, panel or gooseneck.

What a light will not do

A lamp does not replace food. Basil in a 10 cm pot is a garnish, not a week's pesto, however perfect the spectrum. Cold draughts from a back door will undo a good light. So will compost that stays wet in a cool kitchen: the RHS watering note for basil is moist, not soggy, which in a British winter often means watering less than the label on the pot, not more.

If the herbs are the start of an outdoor chilli or parsley row, move to the Tilthwick sowing calendar when the plants are ready to leave the counter. Running cost for a 10–20 W bar over a herb shelf is a few pence a day at the current cap. The working is on the cost page.