Even though indoor plants are inside and protected from the worst of the winter weather, they still need winter care. How you minister to your indoor plants in winter is different from the care they need during spring and summer. If your plants are dying, losing leaves or suffering from pest problems such as scale, it may be because you haven’t adopted a winter indoor plant care schedule.
Why do care needs differ?
The need for different care in winter for indoor plants is due to shorter day lengths in the middle of the year, the cold outdoor temperatures and the use of heating indoors, which can lead to dry air and draughts.
In the lead up to the shortest day of the year around June 21, the hours of daylight shorten and the angle of the sun in the sky is also at its lowest. Even after the shortest day, these low-light conditions continue well into spring. This seasonal change in the path of the sun often reduces the amount of light indoor plants are receiving during winter. It may be necessary to move plants to more brightly lit spots until spring and longer days arrive.
How can I help my plants?
Cold weather outside, particularly overnight, can also be detrimental to indoor plants - particularly those from tropical and subtropical zones such as crotons. Plants that are kept near window glass overnight may suffer cold damage. Move plants away from cold spaces in winter. Even moving them just 30cm away from a window can help and won’t reduce their overall light exposure too much. If moving isn’t possible, consider insulating the window with an insulating film or bubble wrap, which keeps out the cold but lets in the light. Alternatively, draw the curtains as the sun goes down, but don’t forget to reopen them when the day warms up.
Also check there is no cold draught seeping in through or around the window. Not only do these chill cold-sensitive indoor plants, they’ll be making it colder indoors and increasing your heating bills!
Central heating dries the air indoors and may also create draughts especially from ducted heating. These conditions can be very damaging to indoor plants, especially ferns, and may cause leaves or fronds to die or develop brown edges or spotting. To counteract the dry air, mist plants from time to time or stand them on top of a tray of water that’s filled with pebbles. The pebble layer stops plants sitting in water, which could lead to water logging, but allows them to be surrounded by a little extra humidity. Top up the water as it evaporates.
Usually indoor plants are not actively growing during winter, so need less water and liquid feed than from spring to autumn. Check the moisture content of the soil before watering. Also, keep foliage dusted and clean. While this is always important, it's vital in winter for the leaves to access as much light as possible.
A note on flowering plants
Winter is also a time when there are many indoor flowering plants available, such as cyclamen, kalanchoe and orchids. Make the most of these plants indoors while they are in flower, but be mindful that most need a very well-lit space to survive long-term indoors. Where possible, move these flowering plants into a warm, sheltered spot outside once flowering ceases.