How to Make Hydrangeas Turn Color

Overview

Hydrangeas are fascinating plants that can be induced to change the color of their blooms by altering the acidity of the soil in which they are planted. What is usually not completely understood, however, is that soil pH is not the key to change in itself, but the determining factor in the quantity of aluminum the plant is able to take in. Acid soil allows aluminum to be absorbed more readily than does alkaline soil. It is the presence or absence of that vital element that determines flower color. Hydrangeas in containers are easier to regulate than are in-ground specimens.

Basics

Step 1

Place a very large pot with plenty of drainage holes in the place you want your hydrangea.

Step 2

Add rocks or broken crockery to the bottom of the pot to aid drainage.

Step 3

Fill the container with a soil-less mix amended as indicated to produce pink or blue blooms.

Step 4

Plant the hydrangea to the level it occupied in the nursery pot and water it well to settle the soil and moisten it to a couple of inches below the level of the roots. Do not over-water or roots may rot.

Pink Blooms

Step 1

Amend the soil-less mix with dolomitic limestone at recommended levels for the size container you are using.

Step 2

Add the recommended amount of high phosphorus fertilizer to the soil in the hole where the hydrangea will be placed when planting. Mix it into the soil at the bottom of the hole to avoid burning roots.

Step 3

Plant the hydrangea as indicated.

Blue Blooms

Step 1

Amend the soil-less mix with aluminum sulfate or rich, organic compost at recommended levels for the size container you are using.

Step 2

Add the recommended amount of high potassium fertilizer to the soil in the hole, as detailed for pink blooms.

Step 3

Plant the hydrangea as indicated.

Things You'll Need

  • Large pot (a half whiskey barrel or similar-sized container)
  • Rocks
  • Soil-less mix
  • Dolomitic limestone and
  • High phosphorus fertilizer or
  • Aluminum sulfate or rich, organic compost and
  • Low phosphorus/high potassium fertilizer
  • Soil pH tester (optional)

References

  • Hydrangeas Hydrangeas: About hydrangeas color
  • Hydrangeas Hydrangeas: Where to plant hydrangeas

Who Can Help

  • United States National Arboretum: Hydrangea Q & A
  • Spring Meadow Nursery: All about Hydrangeas
Keywords: make hydrangeas blue, make hydrangeas pink, change hydrangea color

About this Author

Deborah Stephenson is a freelance writer and artist, who brings over 25 years of both professional and life experience to her writings. Stephenson features a Bachelor of Arts in Anthropology from University of Arkansas at Fayetteville. She is an anthropologist & naturalist, and has published a field guide on Michigan's flora & fauna as well as numerous political and environmental articles.