Question: I am concerned about the deterioration of my indoor plants that seems to happen about this time every year. Do I need to fertilize them more?
Answer: There are several reasons that indoor plants deteriorate in the winter.
We get so busy decorating during the Christmas holidays that we neglect our indoor plants. Moving and rotating indoor plants can make a big difference in how they survive this lowest light period of the year. Not only are days shorter, but the low angle of the sun in the sky reduces the amount of light energy entering our windows. The greater cloudiness this time of year reduces light even further. I open curtains as soon as the sun comes up to capture the strongest light.
As many plants as possible should be moved close to south facing windows because they give the most natural light. East and west facing windows are next in amount of light. North facing windows give the least amount of light. Even low light tolerant plants will not get too much light in direct sunlight this time of year. However, they should be moved back to indirect light by mid-February.
If you do not have enough windows for all your indoor plants, they can be rotated in and out of direct light at one or two week intervals. Those needing the most light should be left in direct light the longest. If you are not sure of the light requirements of your indoor plants, check the internet or get a book on indoor plants.
Plants also need to be turned frequently so they do not start to grow one sided toward the light. I like to turn my plants clockwise one quarter turn every Monday.
Another way to boost light is to place plants near lamps and leave the lights on all night.
Indoor plants need more grooming this time of year. Growth is slower and some plants will lose as many old leaves as new ones are produced. Once a leaf is half yellow or brown, it is no longer producing food reserves, so it can be removed. Dust can be cleaned from leaves by giving them a shower in the kitchen sink. Shiny leaved plants can be sprayed with leaf shine. Fuzzy leafed plants like African violets do not like anything wet on their leaves.
Since plants are using less water I find myself checking to see if the top of the soil is wet more often before irrigating. If you are fertilizing with liquid fertilizer every time you water, you will be giving plants just about the right amount. Slow release fertilizers such as Osmocote will also give plants a regulated amount of fertilizer.
You will have better plants in the spring if you give them some extra attention now.