Ask Tom: What’s wrong with my house plant?

Dear Tom,

My peace lily, which I got over the summer, is not looking as healthy as it did, and the flowers are withering. What’s wrong with it, and is there anything I should do to revive it?

– Laura

Dear Laura,

During the winter we find a new appreciation for our house plants, as we spend more time indoors and channel all our gardening energies towards our green housemates. The colder months can be incredibly challenging for indoor plants through the heat from radiators and fires, coupled with the extreme nighttime temperatures that can permeate through our windows. This can also lead to a dry atmosphere and that lack of humidity can cause problems for plants, but honestly, one of the biggest issues that house plants face is coping with the increased amount of attention from us while growing at a very slow rate. That attention often manifests itself in an excessive amount of watering in a desire to nurture, but sadly the reality is that most house plants are killed through overwatering. There are a few reasons why your plant might be suffering, and there are some habits that we can modify to help us get better results from house plants while growing them through this potentially difficult time.

1. Overwatering

Although plants don’t stop growing over winter, they grow at a very slow rate and require far less water than they do during the spring and summer. An excessive amount of moisture can lead to rotting at the root and a yellowing of the leaves. It is very easy to revive a dry plant but almost impossible to bring back to life one that is sodden. Insert your finger into the root ball of your house plant; if you can sense moisture on your finger then hold fire with the watering; quite often it’s no bad thing to see the leaves wilting ever so slightly before you give it a little bit of water to sustain it, but most importantly, don’t let your house plant sit in water as this will certainly lead to root rot.

2. Light levels

The light levels are low at this time of year but become even more diminished if our windows are dirty. That layer of dust that can accumulate on windows will impede the transmission of light and therefore reduce your plant’s ability to photosynthesise. Very low light levels will often lead to plants growing in a leggy fashion, which can cause them to lose condition. Regularly wipe down your windows inside and out or move your plant to a better-lit windowsill.

3. Low humidity

Dry atmospheres can be an issue for large-leaved plants, or those from more tropical regions. These house plants are well suited to the darker environment of our homes and the warmth that they provide during the winter; however the way we heat our houses often leads to a dryer atmosphere, causing dried-up or curled leaves with some discolouration. If we want to shower our house plants with love, it’s much better to mist them every couple of days to combat this, rather than adding water at the roots.

4. Direct heat

Avoid excessive fluctuations in temperature by moving your plants away from the direct heat of radiators or open fires. In the other extreme, avoid closing the curtains at night with a house plant trapped behind, where the air temperature can drop significantly.

5. Pests

Pest levels in our gardens can drop dramatically during the winter, but in the house, where it’s much warmer, pests such as aphids, mealybugs and spider mites continue to be very active and feed on our house plants. The sap-sucking pests tend to congregate nearer the soft tips of the plant so can easily be targeted in these areas. Spray a couple of times a week with SB Plant Invigorator until pest levels fall. For mealybugs, dip a cotton bud in some methylated spirit and then dab it onto the insects at the first sign of attack.