Inspect the leaves for signs of disease or insect problems, and always buy only healthy plants. It's best to buy plants already in bloom to make sure you're getting the right variety. Soil, Fertilizer , and Planting Always use commercial potting mixes in your containers as they are sterilized and disease free. Your hydrangeas will thrive in a humus-rich potting soil, and using a soilless mix is also an asset as it helps retain water. There are many potting mixes available with slow-release fertilizer granules that are excellent for container plants.
Acid soils produce blue flowers, whereas alkaline soils produce pink blossoms.
In garden settings, their colors can be changed by adding either sulfur or lime, depending on the color you want to achieve. This is much more difficult in containers because of the small amount of soil you have to work with. When planting hydrangeas, place several inches of potting soil in the bottom of your container first. Center your hydrangea on top of this base soil, then fill in with more soil around the sides so there are no air pockets. Firm the soil gently with your hand, adding a final amount of soil around the top to make sure the roots are covered.