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Hydrangeas, Part 2

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March 12, 2019

The different types of hydrangeas are useful in almost any landscape.  Now let’s focus on successful hydrangea care today on Southern Gardening. 

Hydrangeas grow best when grown in well drained, highly organic soils.  Dig the planting twice as wide as the root ball.  Mix good aged compost with the soil from the hole and plant only as deep as it was in the container.  Current research is showing that planting the crown a little higher than the surrounding soil improves drainage. 

Most hydrangeas will perform best when planted in at least partial shade or filtered light from overhead trees.  Consistent moisture is a must, but overwatering is to be avoided at all costs.  Using a good slow release fertilizer with a 4-1-2 nutrient ratio is ideal.  Apply ½ to 1cup, depending on plant size, and spread around the plants in March. 

Many gardeners have heard that you can change hydrangea flower color.  This is true for the blue or pink varieties of big leaf Hydrangea. 

The color blue is the result of an acidic soil, those soils having a pH below 6.  Beginning in late summer, apply an aluminum sulfate solution, 1 TBS/gallon of water every two weeks until frost. 

The color pink is a result of the soil having an alkaline pH above 7.  Apply 1 TBS of hydrated lime to the soil under the plants in the fall.  For long term pH adjustments you should have the soil tested.  Soil testing supplies are available at your county Mississippi State University Extension office. 

If you would like more information about hydrangeas, the MSU Extension publication number 2574, Hydrangeas for Mississippi Gardens is available at I’m horticulturist Gary Bachman for Southern Gardening. 

Department: Plant and Soil Sciences

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