Hydrangeas are popular garden gifts for spring and summer holidays. Their large showy blooms in white, blue or pink complement most other plants in the garden. Hydrangeas in pots can be moved around the garden as needed. If an area gets too much sun or is too windy the hydrangea can be relocated to a better climate. Hydrangeas do best in moist, well-drained soil with part sun. They are generally disease resistant. Hydrangeas shed their leaves in the fall and at that point potted hydrangeas should be moved to an unheated porch or garage to overwinter.
Select a pot for the hydrangea. The plant may have to be moved so consider the weight of the pot. Begin with small plant in a 5- to 15-gallon container.
Select the place where the pot will go. Hydrangeas need shade in the middle of the day, when sun is strong.
Place about an inch of rocks or small pebbles in the bottom of the pot. This will ensure that the new pot has good drainage.
Add soil to the pot. Fill it about halfway. Use a general purpose soil, but the colour of pink or blue flowers will change with the acidity of the soil. To make the hydrangea turn blue, add aluminium sulphate to the soil. To make a blue flower turn pink, add lime to the soil. White flowers will not change colour.
Remove the hydrangea from the original container. Tap the sides and bottom to loosen the soil. Gently grasp the base of the plant and pull it out. Cut the container off if the plant won't come out easily.
Place the hydrangea in the pot. Keep the root ball intact.
Adjust the soil in the pot so the hydrangea is not too deep in the pot and pat it in gently. The soil should be about an inch below the rim and be even with the top of the hydrangea root ball.
Water the hydrangea. The soil should be moist but not soaking.
Fertilise the hydrangea plant twice a year, in spring or fall. Use a general 10-10-10 NPK (nitrogen, phosphorus and potash) fertiliser. Make sure the fertiliser is not overly high in nitrogen or the plant will produce lots of leaves and no blossoms.
Repot a hydrangea plant about every three years. Put the potted hydrangea on casters to move it easily.