Hydrangea Care
blue hydrangea flower image from Mahoney's Garden Center

Hydrangeas are a well-loved favorite in traditional gardens, and when they are in full bloom, they can be completely spectacular!  If you grow Hydrangeas, you probably know that they have particular needs.  Here is our quick guide to Hydrangea care and pruning, which for some varieties is actually a September maintenance task.  These steps can help keep Hydrangeas healthy and encourage a spectacular show next year!

There are many kinds of Hydrangeas.  If you frequent gardens or nurseries, you have probably noticed a great range of flower and leaf types.  Knowing what kind of Hydrangea you have is crucial to knowing how to care for it.  The main categories go as follows:

Old-Wood Bloomers:

Endless Summer bigleaf hydrangeas in shades of pink, purple, and blue

Old-wood blooming Hydrangeas flower on buds formed the preceding Fall:

Bigleaf Hydrangeas – Native to Japan, Includes Mophead, Lacecap, and most color hybrids

Oakleaf Hydrangea – Native to North America, varieties range in size and flower color

Climbing Hydrangea – While no longer technically a Hydrangea, the Climbing Hydrangea, native to Asia, is a popular addition to shade gardens, and requires similar maintenance.

New-Wood Bloomers:

Oakleaf hydrangeas form a beautiful backdrop in this shady garden by J.Montgomery Designs

New-wood-blooming plants bloom on buds created the same Spring:

Smooth Hydrangeas – Native to North America, includes garden favorite ‘Annabelle’

Panicle Hydrangeas – Native to Asia, new hybrids include ‘Limelight’ and ‘Fire Light’


So why all this talk about Spring and Fall?  This time of year, we are concerned with pruning old-wood-blooming Hydrangeas, as they are already in the process of setting flower buds for next year.  As Mophead and Lacecap Hydrangea flowers fade, now is the ideal time to cut them back and to fertilize your plants for healthy new bud formation.

Old lacecap hydrangea flower is held up to show node where pruning cut should be made

Cut old flowers just above a node where leaves attach to the stem and visible buds are forming.  If you want to maintain the size of your Hydrangeas, cut back branches to the length you would like, without removing more than 1/3rd of the plant, always ending just above a node.  The buds at these nodes will be next year’s flowers and leaves, so this is the only time you should make these cuts.  Late pruning is one of the main reasons for Hydrangeas failing to bloom, as all the potential for flowers actually gets cut off!  In winter, when the plant is without leaves, you can determine if there are branches you want to remove for the health of the plant.

bigleaf hydrangea stem showing new buds at node

What if your Hydrangea is one of the new-wood bloomers?  If you’re still enjoying the show from your drying Hydrangea flowers, feel free to leave them- some of the pinks and reds can be very seasonal and lovely in the Autumn garden.  If you’d prefer to remove flowers, you can do so without ceremony.  You’ll be cutting them back hard in a few months, once they have lost their leaves.  When that time comes, prune branches to just above a bud, at least 1 foot above the ground for an established plant, and remove any damaged branches or congested growth.  For now you can relax and enjoy your Autumn Hydrangea show!

White Annabelle Hydrangea stands elegantly by a wooden gate

Regardless of your Hydrangea type, Autumn is also a good time to fertilize.  Use a specialized fertilizer for acid-loving plants, in the amount suggested by the brand, in Fall and Spring to maintain optimum health and performance.

Very blue bigleaf hydrangea flowers benefit from acidic soil amendment

For many people, Hydrangeas are associated with that beautiful shade of blue.  The other maintenance task that many Bigleaf Hydrangea growers engage in this time of year is keeping their blue Hydrangeas blue.  You may have experienced this color change if a blue Hydrangea you bought went through when the soil it was planted in wasn’t highly acidic… it turned purple, then splotchy pink… a whole variety of colors you hadn’t planned for!  Here in the Bay Area, our soil is not highly acidic, so in order to keep your blues blue, it’s best to add an acidic soil amendment, such as aluminum sulfate or ammonium sulfate, to the soil as new buds are starting to form.  While these products used in the right concentrations do not do much environmental damage, ammonium sulfate is safer for aquatic animals and is less harmful to the skin and eyes.  Many nurseries also offer organic options, which are certainly sustainable but with slightly softer results.

With these simple maintenance tips, you can keep your Hydrangeas looking fantastic!  When planting hydrangeas here in the East Bay, keep in mind that they require a lot of water in the full sun, so you may consider growing them in partial shade, in containers, or in a focal spot where you plan to invest more water in your landscape.  Sustainability and enjoyment of your favorite plants can go hand-in-hand.  Loving your garden is everything!