How much light your houseplants lose in winter, city by city
Daylight on 21 June and 21 December in 16 cities, from Lisbon to Helsinki, and how to care for houseplants in winter as the light drops.
Winter daylight in Europe is shorter and weaker everywhere, but not by the same amount. Between 21 June and 21 December a houseplant in Lisbon loses 5 h 25 of daylight a day, and one in Helsinki loses 13 h 07. Plants turn light into the food they grow on, so less light means slower growth and less water used.
Winter daylight for houseplants, city by city
Day length is the time between sunrise and sunset, and it is the simplest measure of how much light a plant can get in a day. In Europe it depends on the season and on how far north a city lies.
The longest day is the summer solstice on 21 June, the shortest the winter solstice on 21 December. The table compares those two days in 14 European cities, with New York and Toronto added for reference.
The last column is the December day as a share of the June day. In Barcelona the day on 21 December lasts 9 h 11, which is 61% of the 15 h 10 it lasted on 21 June. In Helsinki the same comparison gives 5 h 49 against 18 h 56, or 31%. The halfway point runs between Paris, which keeps 51%, and Brussels, which keeps 48%.
That line decides how much a room changes over the year. In Brussels, London, Amsterdam, Berlin and every city further north, a spot a couple of metres from the window that is bright in June can be dim by December. In those cities the plants that cope with winter away from the glass are the same ones you would pick as low light houseplants.
Do the clocks going back take light from houseplants?
No. On Sunday 25 October 2026 the clocks in the EU and the UK go back one hour, ending summer time, and New York and Toronto follow on 1 November. Sunrise and sunset then happen an hour earlier on the clock, but the time between them stays the same. A plant in a Berlin living room gets as much daylight on the Monday after as on the Saturday before.
The clock change makes the dark evenings noticeable, but by then most of the light has already gone. On 25 October the day lasts 10 h 44 in Barcelona, 10 h 09 in London and 9 h 23 in Helsinki. That is 4 h 26, 6 h 29 and 9 h 33 less than on 21 June.
After the clock change the days keep getting shorter until the winter solstice. Barcelona loses another 1 h 33, London 2 h 19 and Helsinki 3 h 34, which makes late November and December the darkest weeks of the year for houseplants in every European city in the table.
Why winter light for plants is weaker than the hours suggest
Winter daylight is not only shorter, each hour of it is also weaker, because the sun stays low in the sky. Sun height is the angle between the sun and the horizon, where 90° would be straight overhead. At midday on 21 December the sun reaches 28° in Lisbon, 25° in Barcelona, 15° in London and 6° in Helsinki. In Barcelona in June it reaches 72°.
A low sun weakens light in two ways. Its rays arrive at a slant, so the same beam spreads over a larger surface, the way a torch held at an angle lights a wider but dimmer patch. And the light crosses more of the atmosphere before it reaches your window. Both effects are strongest in northern cities, where the December sun stays only a few degrees above the horizon.
The low angle also changes what each window gives a plant, depending on the compass direction it faces. Illinois Extension notes that north and east facing windows that gave good indirect light in summer can become too shaded in winter, and the RHS advises moving houseplants to a south or west facing windowsill when the days are short.
How to care for houseplants in winter light
Caring for houseplants in winter starts with where they stand, because light is the main thing that limits their growth in the dark months, according to Illinois Extension. The Royal Horticultural Society advises bringing plants out of dark corners while the light is low, and warns that radiators and cold windowsills behind curtains can damage leaves.
The simplest routine is to move every plant once, in late October around the clock change, and leave it there until the days lengthen in spring. The steps below take a few minutes per plant.
Watering houseplants in winter, when the light drops
Houseplants need less water in winter because water use follows growth. A plant uses light to turn water and carbon dioxide into the sugars it grows on, as the RHS explains, so when short days slow growth down it takes up less water. Illinois Extension advises watering less often and keeping the soil on the dry side, without ever letting the plant wilt.
Light also decides how fast the soil dries. A plant you moved to a bright south facing window in Madrid will need water sooner than one left at the back of a north facing room in Brussels. Check the soil with a finger before every watering instead of keeping the summer rhythm. Soil that stays wet in low light is one of the causes of yellow leaves.
Wet soil in winter also suits fungus gnats, small flies that breed in the top layer of potting mix when it does not dry out. Letting that layer dry between waterings is the same habit that protects the roots.
Which houseplants cope with winter light in northern cities
In Dublin, Copenhagen, Stockholm and Helsinki the shortest day lasts seven and a half hours or less, so winter is easiest for low light tolerant plants, the ones that stay healthy on little light even if they barely grow. The ZZ plant is one. It stores water in its thick stems and in the swollen rhizomes under the soil, which suits months of slow growth and little watering.
The snake plant is the other dependable choice for a dim winter window in a northern flat. It needs very little water while it is not growing, so in winter let the soil dry right through between waterings.
Pothos keeps going in modest light but slows down until spring. If a pothos drops older leaves in December, move it closer to the window before you change the watering, because in winter a lack of light is the likelier cause.
How we worked out winter light for houseplants
Every number on this page is calculated rather than estimated, and the one thing it cannot tell you is the light in your own room.
Conclusion - houseplants in winter
In Paris and every city south of it, from Vienna to Lisbon, winter takes between a third and a half of the summer daylight, and the brightest window plus less water covers it.
In Brussels, London, Amsterdam, Berlin and further north the loss passes half, and in Stockholm and Helsinki it reaches two thirds. There, a grow light is worth it for any plant that cannot stand beside a south facing window. Everywhere in Europe, the days lengthen again from 21 December.
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