Repotting Rules

By Laurel Aiello | Fort Collins Nursery

When was the last time you repotted your houseplants? If it’s been a while, take a look at them and see what they’re trying to tell you. Roots squeezing through the drainage holes or pushing the plants up and out of their pots are obvious signs they need more space to grow. Other things to look for are compacted or quickly drying soil, topheaviness, slow growth, leaf yellowing and abnormal shedding. Spring is the best time to repot houseplants, as they’re coming out of their winter dormancy and, like humans, need a bit of a reset.

The best way to tell whether a plant is ready for repotting is to remove it from its current pot. Start by wiggling a ruler or butter knife between the soil and inner edge of the pot, then saw around the inside to loosen the roots before tipping the pot over and gently pulling the plant out by its stems. Shake off some of the old soil to make room for the fresh potting mix.

Plants with firm, dense and coiled roots usually need a new pot that’s a couple inches wider and taller, or up to four inches wider and taller if the plant is large and very root bound. Any bigger and there will be too much empty soil space, which will retain water and cause root rot. Cacti, succulents and certain foliage plants, like snake plants and bird of paradise, prefer to remain rootbound.

If the roots are mushy, smelly or full of fungus gnats and other bugs, the plant has root rot and should either be repotted in the same pot or a smaller one. Shake off as much of the old soil as possible, then remove any rotten roots with pruners and rinse the remaining roots with lukewarm water to get rid of any remaining rot.

Even plants that don’t have bound or rotten roots benefit from being repotted in a well-draining potting soil every year or two, depending on how quickly they grow (cacti, succulents, bonsai, carnivorous plants and orchids require specific soil). That’s because over time, the roots deplete the soil of nutrients and cause it to harden, even with regular fertilization.

Always choose a pot with a drainage hole so that you can water the plant thoroughly without worrying about the soil getting soggy. Placing rocks at the bottom of a pot without a hole doesn’t necessarily prevent root rot, as water still gets trapped inside. If you like the look of a pot that doesn’t have a drainage hole, drill one with a diamond drill bit or use it as a “cache” pot by potting the plant in a plastic nursery pot and setting it inside the decorative pot when it’s not being watered.

When repotting houseplants, you want messy roots and a messy hole, meaning that you should uncoil the roots and place them on a layer of loose soil before lightly packing the remaining soil around the root ball. This allows the roots to stretch out and easily find their way into the new space. Packing the soil too tightly will suffocate the roots.

Finally, water your plants into their new soil. If a plant needs extra love, mix a slow-release fertilizer such as Osmocote into the top inch of the soil before watering, then watch it come back to life in the coming weeks.