Endless Summer Hydrangea

Posted by Sunset Garden Experts on

endless summer hydrangea blue and pink



Endless Summer is the first Hydrangea that blooms on old and new growth with the ability to re-bloom all summer long, here are some tips to make Endless Summer® the centre of attraction in your yard.      

Northern Climate Winter Care

To ensure overwintering success in the first year, the following is recommended:

  • Stop all applications of fertilizer after mid-August to acclimate the plant for winter.
  • Keep the soil moist through the fall months until the ground is frozen.
  • Cover the plant with a four-inch layer of organic mulch (wood mulch, leaves, etc...).  There is no need to cover all stems to the tip or to cut them back.
  • Covering should be done when fully dormant (around end of November), or at the same time you would cover perennials in your garden.
  • In spring uncover with your perennials when the ground is no longer frozen.  The plant will grow from the base of the plant and also from any old branches that survived winter.
  • Be patient.  Growth will come slowly until the heat of late spring stimulates the plant to grow faster.
  • Once you see growth you can prune back the old branches to a finger width above the new green growth.
  • Sit back and watch your plant grow and bloom, which depending on your climate should be some time around the middle of July.



Endless Summer® Hydrangea is very forgiving and will not suffer if left unpruned or pruned at the wrong time.  In fact, young, recently planted shrubs are best left alone.  Unlike other Hydrangeas, your Endless Summer® will bloom on both old and new wood, branches that grew last year and the new branches from this year.  Another unique feature is that this hydrangea will continue to set buds and bloom throughout the season; deadheading the spent flowers will encourage this.  Feel free to cut the blooms for drying or fresh cut in vases because you will actually encourage the plant to produce more blossoms.  Spring is the best time to prune.  Many people like to leave the spent blooms on their plant because it adds winter interest.  It may also act to insulate the new buds from frost and cold.  They should be removed in spring however.

Changing Flower Colour

To encourage flowering, we recommend a fertilizer low in nitrogen and high in phosphorus, with a number over 30.  For instance, a N-P-K ratio of 15-30-15 would be ideal.        

Endless Summer hydrangeas are unique in that their flowers can change colour.  The colour of Endless Summer Hydrangea blossoms vary depending on the soil's pH and its ability to absorb aluminum at different levels.  An alkaline soil produces pink colours.  An acid soil produces blue flowers.

To make your soil more alkaline you need to apply dolomitic lime near the plant. You can also use fertilizers with high levels of phosphorus.  Phosphorus helps to prevent aluminum from being taken up in the plants system.

To make your soil more acidic you need to apply aluminum sulphate near the plant. 

It is possible to manipulate the colour of hydrangeas, but one word of caution: many people have killed their plants by applying too much aluminum sulfate. More is not better.

**The original Endless Summer would change from blue to pink depending on the acidity of the soil however there are new varieties of endless summer hydrangeas available now. Summer Crush is a pink only variety which only changes its tone of pink depending on the acidity of the soil. Bloomstruck is one which will change from tones of purple to pink but has a harder time achieving a deep blue colour.**

Extra Tips for success:

  • Ask the Garden Centre where you purchased your plants for what's recommended to acidify the soil in your area.
  • Follow directions carefully on the product you purchase.
  • Thoroughly water the plant before adding any acidifier.
  • Adding large amounts of organic matter, such as peat moss and composted leaves, will acidify the soil as they break down.

Remember to check the pH of your water.  If you are trying to turn your flowers blue and you have hard water, it will be difficult to achieve.  Also, remember that concrete foundations and walkways tend to leach lime, raising the pH level in that area.

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