Why transplant? To keep plants healthy.
It’s time to repot if plants tip over, dry out too quickly, or have many roots extruding. In general, most plants should be repotted every year or two to replace worn out or missing soil. Slower growing plants or cacti need to be repotted less often than others.
Plant should be healthy, preferably not in full bloom. Flowering plants are using their energy to bloom and unhealthy plants might find the repotting disruption overly stressful. Spring is a great time to repot, it’s just before the active growing season. Water plant very well several days previously to work with slightly moist, not wet or dry soil.
Gather: Potting Soil not yard dirt that might be contaminated, larger pot, material to cover drainage holes such as gravel or old window screen, scissors / knife to trim plant leaves or roots, sand for plants that want more drainage such as succulents, and a working surface.
Pot should be clean, have drainage holes, and be an inch or two larger than the current pot. Add gravel or other materials to slow water drainage, this prevents the fresh soil from leaking out of the pot. Soak porous clay pots before repotting and consider planting in an inexpensive pot to move between several seasonal decorative pots.
Remove plant from pot
Gently remove plant loosening plant from pot. Try gently squeezing pot or slipping a thin knife down between the soil ball and inside of pot, tipping pot sideways, and tapping bottom of pot. Plastic pots can be cut off and some extruding roots can be trimmed off.
Care for the plant
Massage large roots to remove some old soil, do not disturb small fibrous roots such as begonia or African violets. Large or circling roots can be trimmed but generally not more than 20% of roots. Remove old leaves, trim top or divide as needed.
Place in new pot
Add new soil in bottom of pot so the top of the root ball is at the same depth as before. The new pot should have a lip around the root ball to hold water. This gives water a chance to be absorbed instead of rolling of the top. Don’t squeeze plant in new pot, there should be enough room to grow. If you are adding any soil amendments now is the time to add them.
Tap soil in around the sides of the new pot to remove large air pockets. Use gentle pressure but don’t jam or pack the soil in tightly. The soil should be firmly in place not compacted hard.
Don’t forget to water in. For cacti or succulent wait a week or two before watering in. Generally potting soil contains some fertilizer so the repotted plant won’t need to be fed for several weeks.