Your first step should be to wash your plants either in the sink or the shower, depending on size. You can use crumpled aluminum foil around the stem at the top of the pot to prevent soil from washing out and clogging your drains. Let the plant dry completely before placing it back in a sunny window.
If you discover insect pests or disease, evaluate the situation and deal with it quickly. For some plants infected with aphids, a swish in soapy water may be all that is needed. Mealy bug --- that insidious cottony mass that loves to hide in the joints of choice gardenias and succulents like jade—can be killed with rubbing alcohol applied with a cotton swab. It may take many applications, however. If you need a heavy-duty pesticide, consult the experts at your local independent garden center.
Once you know you have healthy plants, decide whether they need repotting. If the plant seems to be top-heavy in its pot or there are roots protruding from the drainage holes, it definitely needed repotting. If you are unsure about its status, unpot the plant onto several layers or newspaper to check the root system. If the roots are taking up all the soil in the pot, repotting is in order. Check the color of the roots. Dark brown and mushy is an indication the plant has been overwatered—the most frequent cause of house plant demise. White roots indicate good health but they need soil to do their job.
When repotting, choose a pot that is just one size larger than the current home, make sure it is clean (soak pots in a 10 percent bleach solution for 10 minutes and then rinse) and then use appropriate packaged soil mix to give the plants a boost. There are special formulations for African violets and their relatives as well as special soils for cacti and succulents. When repotting, tamp the soil down to be sure you aren’t leaving air pockets, water well and hope for new growth.
Plants that don’t require repotting may just need a fertilizer boost. Fish emulsion is great, but some people can’t stand the smell indoors. Otherwise choose a general houseplant fertilizer that is water soluble and apply in half strength. You don’t want to burn the roots or shock the plant too much. Plan on fertilizing regularly from now on.
You may be tempted to purchase new house plants to spiff up your collection. Remember always to isolate new plants from old ones in case the newbie carries insect eggs or other problems that can spread. A week or two apart from your treasured standbys should reveal any problems.
If you wish to multiply your plants by taking cuttings, now is an ideal time to do so. Some plants like ivy or impatiens will root well in water. Others require soil. Take a short side stem and cut it at an angle. Insert it in water or soil. If using soil, a rooting hormone is helpful. It’s also a good idea to cover the pot with a plastic bag to retain moisture. Make sure the bag doesn’t touch the plant. A hoop made from a wire clothes hanger can be effective. If you are doing numerous cuttings you can put the pots in a nursery tray with a plastic cover. The cuttings should root within a month at the most.
Once you get your house plants in order, you can start thinking about seed-starting under light, looking for early signs of flowering bulbs and planning additions to your food and ornamental gardens. Spring is just around the corner.