Hoya, or wax plant, is an easy-going houseplant that will thrive for many years with a minimum of care, as long as it has adequate warmth, light and water. However, like all indoor plants, hoya will grow too large for its container from time to time. When this happens, it's time to repot the hoya to a larger container. Re-pot hoya during spring or summer, when the hoya is actively growing.
Purchase a planting container no more than one size or 2 inches larger than the hoya's current container. Put a paper coffee filter or a paper towel on the bottom of the container to prevent soil loss through the drainage hole.
Hold the hoya's container with one hand, and slide the hoya carefully out of the container with your other hand on the top of the potting soil. Guide the hoya, but don't hold it by the stem. Check the condition of the hoya's roots, and trim off any roots that are soft, black or bad-smelling with clean, sharp scissors. Healthy roots will be light in colour and firm.
Put a small amount of commercial potting mix in the bottom of the container and place the hoya in the container. If necessary, adjust the potting mix in the bottom of the container so that the hoya's root ball is about an inch lower than the top of the new container.
Fill the container with potting mix, and tamp the potting mix gently around the hoya's roots with your fingers. Water the hoya thoroughly, and allow the water to run through the drainage hole. Return the hoya to filtered or indirect light.
If you're repotting your hoya into a container that has been used previously, scrub the container with warm water and detergent, then rinse it with a mixture of 1 part household bleach to 9 parts water.