Tips on repotting houseplants

By Melanie Mathieson
Gardening Guru

There are many types of containers choose from when repotting houseplants. But a good container should be large enough to provide ample room for the soil and roots, have sufficient head room for proper watering, provide bottom drainage and be attractive without competing with the plant it holds. Containers may be fabricated of ceramics, plastic, fibreglass, wood, aluminium, copper, brass, and many other materials. After you consider all of this and narrow the selections it down then you can pick a pot that is well suited for the type of plant and one that matches your décor.
Unglazed and glazed porous clay pots with drainage holes provide excellent aeration for plant roots and are considered by some to be the healthiest type of container for a plant although they can be easily broken. Clay pots are highly recommended for cacti and cyclamen.
Ceramic pots are usually glazed on the outside and sometimes also on the inside. They are frequently designed without drainage holes. This necessitates careful watering practices. Containers with no drainage are not good houseplant pots. Small novelty containers have little room for soil and roots and are largely ornamental. They should be avoided. It should be noted that putting pot chips, clay pot shards or gravel in the bottom of a pot does not improve soil drainage; they only provide a small space beneath the soil where some excess water can drain inside the pot. Keep in mind that decorative containers without drainage holes can be used as a slipcover for a less attractive pot. Just make sure that the pot inside is not sitting in excess water after you water the plant.
Plastic and fibreglass containers are usually quite light and easy to handle and manufacturers have worked really hard to make their container look like other products such as iron, wood, ceramic or cement. Plastic pots are easy to sterilize or clean for reuse, and because they are as not porous as clay pots they need less frequent watering and tend to accumulate fewer soluble salts in the soil. Plastic or fibreglass pots are definitely okay to use and offer the best selection in matching your décor or colour scheme.
I mentioned that you should repot any new plants as soon as you get them home but you should also repot your actively growing house plants on a yearly basis. At the minimum foliage plants require repotting when their roots have filled the pot and are growing out of the bottom of the pot. By potting annually you will refresh the soil, possibly eliminating any soluble salt or fertilizer buildup, inspect the roots for disease, damage or rot. Some plants can even be divided at this time.
The pot you select for repotting should be no more than 2 inches larger in diameter than the pot the plant is currently growing in; should have at least one drainage hole; may be either clay, ceramic or plastic and must be clean. When you repot annually you should repot your plant into the next size pot (increase by 2 inches usually). A new plant can be placed in the same diameter pot if it is a small plant. If reusing a pot, wash any soluble salts from clay pots with water and a scrub brush and wash all pots in a solution of 1 part liquid bleach to nine parts water in order to kill any disease organisms or insect eggs.
Most plants are removed easily from their pot, if the lip of the container is knocked upside down against any solid object. Hold your hand over the soil, straddling the plant between the fore and middle fingers while knocking it out of its present container.
To repot, place drainage material in the bottom of the pot, if desired, and some new soil. If the plant has become root bound it will be necessary to cut and unwind any roots that encircle the plant, otherwise the roots will never develop normally. If the old soil surface has accumulated salts, the top inch should be removed and thrown away.
Set the rootball in the middle of the new soil. Your potting soil mixture should be lightly moistened before repotting begins. Fill soil around the sides between the rootball and pot. Do not add soil above the original level on the rootball, unless the roots are exposed or it has been necessary to remove some of the surface soil. Do not pack the soil. To firm or settle it, tap the pot against a table top or gently press the soil with your fingers.
After watering and settling, the soil level should be sufficiently below the level of the pot to leave headroom. Headroom is the amount of space between the soil level and the top of the pot that allows for watering a plant. A properly potted plant has enough headroom to allow water to wash through the soil to thoroughly moisten it.
Now you have given you plants a new home with fresh soil. They will benefit from this and you will be rewarded well.