The problem

Winter is often seen as downtime for houseplants, so they can get forgotten. Colder days mean the heating is on, the air dries out, and draughts creep in at every window or door. Tropical plants that thrived in summer can start to sulk. Could a digital thermometer and hygrometer to monitor the humidity help redress the balance?

The hack

Pop the cheap gadget among your plants for a live update on temperature and relative humidity, often with a record of the daily high and low. The idea is that instead of guessing whether your calathea is cold or your fern is fading in the dry air, you measure and move the plant or treat it accordingly.

The method

Place the device at plant height in the spot you want to check, not the middle of the room. Leave it for a couple of days to capture overnight dips and daytime peaks, especially on windowsills, which can swing dramatically between the two.…