Q: I bought lots of new houseplants last summer to brighten my bedroom and home office. I fed them regularly during the warmer months with an all-purpose houseplant fertilizer and they thrived. Now winter is here, should I be feeding them less?
A: Usually, the answer is yes. The majority of indoor plants don't need feeding in winter, nor do they need much water. 'Most houseplants enter a dormant or resting phase during winter,' explains Kayla Gajdascz, the co-founder of Mental Houseplants. 'Their growth slows down significantly, and they require less energy.' Fertilizing indoor plants during this period can lead to an excess of nutrients that cannot be used effectively, Kayla continues. 'This can lead to a buildup of minerals in the soil, potentially causing fertilizer burn to the roots.' It can also result in wilted and yellowing leaves, sometimes with brown tips. What's more, applying fertilizer may stimulate excessive foliage growth that the roots can't support, adds Kiersten Rankel, a plant expert at Gregarious, Inc.
PLANTS THAT CAN BENEFIT FROM FERTILIZING IN WINTER
There are, however, a few exceptions to this 'no feeding' rule. These are the plants that continue to grow in winter, such as the ones that produce winter flowers. For instance, you may wish to consider fertilizing winter-blooming orchids, says Kayla. Amaryllis – beautiful, festive flowers that grow from bulbs – are another example, as are indoor cyclamen. Vladan Nikolic (Mr. Houseplant) suggests using a phosphorus-rich fertilizer to promote flower development on winter-blooming houseplants. 'Remember that fertilizers cannot be a substitute for the lack of light,' he adds. The Miracle-Gro Blooming Houseplant Food, available from Amazon, is a popular choice.
Additionally, if you provide grow lights and maintain a warm and stable indoor environment, some other plants may continue to grow and could require light fertilization, Kayla says. If you can see new leaves and shoots, it’s safe to fertilize, Vladan adds.
WHEN SHOULD YOU STOP FERTILIZING HOUSEPLANTS?
'The best practice is to stop fertilizing six weeks before the onset of shorter daylight hours,' says plant expert Kiersten Rankel. The soil will retain nutrients for several months, she adds.
WHEN SHOULD YOU START FERTILIZING HOUSEPLANTS AGAIN?
'Resume fertilizing when new growth begins to emerge in spring,' says Kiersten Rankel. 'This supports plant development.'
'In general, it's best to avoid fertilizing houseplants in winter, respecting their natural growth cycle,' Kayla concludes. Instead, she advises focusing on providing optimal winter houseplant care through other means, such as maintaining humidity. Repotting should also be avoided, she adds. Maintain temperatures above 55°F and place your plants in the sunniest window possible, recommends Kiersten. 'Check soil moisture periodically and water only when partly dry,' she adds. This is important for reducing the risk of root rot during the colder months – a potentially fatal problem for plants.