Hydrangeas typically grow as an outdoor shrub, but the florist's variety makes a suitable houseplant. The orbs of soft pink or blue flowers bloom in spring and early summer. The large, bright green leaves continue to add colour to your home for most of the year. With proper care, the hydrangeas bloom again each year, but the plants require repotting every one to two years to ensure best root growth. Growing hydrangeas in a pot that becomes too small inhibits flowering and eventually causes the health of the plant to decline.
Cut back the hydrangea once the last flower fades. Trim each stem back to within 1//4 inch of a leaf set or leaf node, leaving two leaf sets or nodes on each stem.
Combine 1 part potting soil with 1 part peat moss. Water the mixture until it is evenly moist throughout.
Fill a new pot one-quarter full with the peat mixture. Use a pot one size larger than the current hydrangea pot, and only use pots with bottom drainage holes.
Lift the trimmed hydrangea from its old pot. Set it into the new pot. Add more peat mixture beneath the hydrangea roots, if necessary, so the top of the root ball sits 1 inch beneath the rim of the pot.
Fill in around the hydrangea roots with the peat mixture. Water thoroughly after repotting to settle the soil around the roots.
Place the repotted hydrangea outdoors after frost danger passes in spring. Provide it with water and light afternoon shade through the summer months, but bring it indoors before fall frost.