As the days grow longer and the sun shines more frequently in Michigan it’s time to give the houseplants a little attention and maybe some fertilizer. Beginning in March most houseplants respond to the lengthening days and brighter light by putting on some new growth. They’ll often require water more frequently and they may require fertilization.
Whether you need to fertilize houseplants depends on many things. If the plant is already growing vigorously and too much growth could be a problem, then fertilizer probably isn’t needed. Remember plants make their own food from the process of photosynthesis. The fertilizer we supply them is more like us taking vitamins, it replaces certain minerals that the plants may be lacking because they are not growing in natural soil. Some plants seem to be able to exist very well without much supplementation.
If a plant is already touching the ceiling and sinking it into the floor isn’t an option, then it’s probably not a good idea to fertilize it. However if the plant isn’t growing well, appears weak and sparsely leafed, then fertilizer may be needed. If you have flowering plants like African violets, geraniums, or begonias, fertilization will allow them to put on a good bloom show.
Fertilization may also increase the plants resistance to disease and insects, just as vitamins boost our immune system. If a houseplant is struggling with an insect infestation like scale or spider mites, or a disease, fertilization may allow it to survive.
To fertilize houseplants use a water soluble fertilizer formulated for houseplants or a general purpose plant food that includes houseplants on its label. Read and follow the label instructions carefully for mixing the fertilizer with water. There are even organic houseplant fertilizers such as fish emulsion on the market.
Do not make the fertilizer solution too strong! Most commercial fertilizers are formulated with various “salts” and these build up in the medium or soil of houseplants over time. You may notice the buildup as a crusty whitish-yellow substance on the soil surface or on the pot. After a while this accumulated salt will harm the plant roots and cause the plant to grow poorly or die.
To get rid of accumulated salts you can re-pot the plant in clean potting medium or you can leach it. Leaching is placing the plant in its pot in a sink or bathtub and letting warm water gently flow through the soil continuously for an hour or two. The water needs to drain out of the pot at the bottom. When you water your plants and catch the water that drains out of the pot in a saucer that saucer should be emptied a short time later. If the water is sucked back up into the pot the salts that were leached out will be re-absorbed too.
Houseplants need fertilizer once or twice a month from March until the beginning of September. After September in Michigan, most houseplants slow their growth because of lower light intensity and shorter days. Fertilizing then may cause more salt build up in the soil. There are exceptions to this rule, usually for flowering houseplants or plants under intense artificial light.
If you move houseplants outside for the summer they will probably benefit from careful fertilization. They are less likely to develop salt buildup if they are watered often and the pot drains freely. Fertilize them when you fertilize containers and hanging baskets, about every 10 days.
Before beginning a fertilization program because your plants look poorly, make sure you do not have a watering problem-too much or too little- or a temperature problem, your room is too hot or too cold. Fertilizing in these instances may actually harm the plant.
Lush, beautiful houseplants are usually carefully fertilized by their owners. Your houseplants may only need that little extra boost to really shine.
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