Are Christmas lights bright enough for our houseplants?

These plants obviously need light to grow and flower and with many fewer hours of sunlight just now, natural daylight is at a premium. Our houseplants are, of course, used to the conditions we have provided but these are now changing as we decorate for the festive season, making mid-winter even more stressful for houseplants.

As a general rule, houseplants do better in natural, rather than artificial, light. Sunlight contains a higher proportion of the blue light they need to grow strongly.

Only grow-lights and LED lights contain significant amounts of blue light whereas many of our lightbulbs don’t. Even when we normally use LED lights in a room, we often dim them over the festive season. We want to highlight all the cheery strings of lights decorating the walls and hugging the Christmas tree in the corner of the room. So with this more subdued lighting, we need to compensate by giving our plants as much natural light as possible. Try moving those species, like echeverias and kalanchoes, that need a brightly lit room with plenty of sunlight closer to a window. Whereas shade-tolerant plants like Ficus benjamina and ivies (Hedera), can tough it out in a dim hallway or at the back of a room.

When writing this piece, I used my little light meter and found that a south-facing window sill registered a light intensity of four – twice as much brightness as that in the middle of the room. Even during this dull wet day, the outdoor measurement was 56, with 35 in the greenhouse. This would be similar to a conservatory.

So a houseplant that needs the indirect light away from a window in June will now be in deep shade and would appreciate a spot where it can get some of the weak winter sun. Use it as part of your window decorations and it can still be healthy come January.

Plant of the week

Chicory ‘variegato di Castelfranco’ is a beautiful non-forcing chicory that is invaluable in autumn and early winter salads. Its light green leaves are splashed with maroon and the innermost heart leaves are a creamy yellow. Grow in partial shade and moist ground and the leaves will not be bitter. Hearts can be quartered, brushed with oil and grilled or braised and served with toasted walnuts.

Really hard frosts will turn the outer leaves to slime but rescue the plants and the innermost ones will still be usable; keep fallen leaves off the plants as they can encourage rots. A brilliant reason for growing chicory is that it doesn’t seem to appeal to slugs.