As the weather cools, a gardening project we could undertake involves re-potting our house plants. For achieving the maximum growth and quality of our plants it’s best to repot them every couple years or so, if not more often.

If you water regularly and your plant still wilts and more leaves are yellowing and dropping off, or it has been a long time since the plant had any new growth, it’s very likely your plant needs to be repotted.

The repotting process is pretty straightforward. You can lay the plant on its side and either knock on the sides of the container or use an old kitchen knife to run around the inside edge of the pot to loosen the root ball, then gently pull the plant out of the pot. You can remove some of the old soil from the sides of the root ball and if there are white mineral deposits on the top of the root ball, remove those also. It’s best to repot in a clean container that is at least 2 inches larger so you have space for new root growth.

No matter what pot you use, you always want the pot you are planting into to have drainage holes. If you want your plant in a ceramic or glazed pot without drainage holes then plant it in another pot and place that pot on a layer of rock inside the ceramic pot. Clay pots are good if you have a tendency to overwater, as they absorb moisture through the walls of the pot and evaporate it out that way. However, they break easily, and big pots can be expensive. Plastic pots are light, easy to handle and can be inexpensive and come in lots of shapes and colors.

Just as the quality of soil is important for your outside plants, it is the same for houseplants. The main qualities you want in your soil include good aeration and drainage, and, for most non-cactus or succulent plants, you want good humus content.

Unfortunately, many of the cheaper potting soils don’t have those characteristics. You put that soil in a pot, water it and it sets up like concrete. There are many separate ingredients you can buy and mix to make up your own soil, which is what I did for years, or there are some good already prepared soil mixes on the market if you are willing to spend just a little bit more, which is what I would suggest for most people and what I do now.

For people who place their houseplants outside for the summer there might be insect problems to deal with when you bring the plants back inside, especially if you don’t repot your plants. There are a number of insects you could bring indoors with your plants and the ones that I hear about the most are aphids, spidermites and fungus gnats.

You can control aphids and spidermites by spraying the plants multiple times with an insecticidal soap or mixing up no more than 3 to 5 percent of a non-scented, non-colored dishwashing liquid with water. You also can mix up a bucket of soapy water and turn the plant upside down and swish it around in the soapy water. It wouldn’t hurt to repeat this a couple of times.

Fungus gnats, however, are a bit more of a problem. The larvae are often found feeding on fungi growing on the potting soil media and a casual inspection won’t necessarily reveal them. The larvae can damage roots while burrowing through the soil. However, the biggest nuisance is the adults, which don’t feed on the plants. It’s pretty common to have them emerge in high numbers from the potting soil and fly around your house and your face during the winter months. Before bringing a plant back inside you can remove the soil from the roots of the plant and replace it with new soil or you can use a type of Bt called Bacillus thuringiensis israelensis or Bti. You would mix this up as a soil drench and pour it over the root ball of the plant.

Houseplants not only provide us many colors and shapes to liven up our rooms for the winter, but just like our outdoor plants they take in carbon dioxide, give out oxygen, remove harmful chemicals and airborne bacteria and fungi from the air and also absorb noise. Although depending on the number of people you have in your household you might not always think they absorb enough noise.

For more information about these issues contact the Utah State University Extension Grand County office at 259-7558.