Hydrangea Care Through Winter Cold
Ensures Summer Glory

Hydrangea macrophylla in winter.

Often I am asked, "Why don't my hydrangeas bloom?"

Usually the answer lies in what happened to your hydrangeas during the preceding winter or right at winter’s end.

Except for two species ( H. arborescens & H. paniculata ), hydrangeas form flowers during the previous growing season (on so-called "old wood"). These nascent flower buds have to survive the winter and the unstable weather of early spring to blossom in full glory in our summer gardens.

Protecting Hydrangeas through Winter

Winter protection of hydrangeas has two parts:

  • what to do through the winter
  • what to do at the end of winter, once buds along the stems emerge from dormancy

Winter care can be as simple as doing nothing – if minimum temperatures in your garden do not threaten your hydrangeas and if a late frost doesn't occur after the stems have emerged from dormancy. However, most of the showy hydrangeas are foreigners in the US. and may need some protection, particularly if you like to push zonal gardening limits.


 

 

 

 

 

 

 

Hydrangea paniculata in January.

Find Your Zone, Check Your Species

To understand which hydrangeas need protection, determine the lowest temperature likely in your garden by consulting the USDA Hardiness Zone Map . The map bases its estimates on years of historical data.

Protection through the winter varies by species. The common hydrangea species are

  • Hydrangea anomala subsp. petiolaris (climbing hydrangea, a vine)
  • Hydrangea arborescens (smooth or native hydrangea – eg., 'Annabelle')
  • Hydrangea aspera
  • Hydrangea macrophylla (bigleaf hydrangea – the most common species – eg., 'Nikko Blue')
  • Hydrangea paniculata (panicle or PG hydrangea – eg., 'Tardiva')
  • Hydrangea quercifolia (oakleaf hydrangea – eg., 'Snow Queen')
  • Hydrangea serrata (mountain hydrangea – eg., 'Blue Billow')

Take Action If ...

...the lowest temperature in your garden is

  • Always above 0 degrees F – No protection of any species needed through the winter. Once established, all commonly grown hydrangea species are cold hardy in this temperature range.
  • Always above -10 degrees F – Protect Hydrangea aspera and certain selections of Hydrangea macrophylla.
  • Always above -20 degrees F – Protect Hydrangea macrophylla..Hydrangea serrata and Hydrangea quercifolia (depending on the cultivar) may need protection.
  • Always above -30 degrees F – Protect all hydrangeas except for Hydrangea arborescens & Hydrangea paniculata.
  • Always above - 40 degrees F – Protect all hydrangea species.

If your hydrangeas are young or newly planted , you may need to take extra precaution.

How to Protect Your Hydrangeas

Hydrangea macrophylla & hydrangea serrata species most commonly require winter protection.

Encircle the shrub with a wire cage.

Carefully wrap the stems using burlap or spunbonded polypropylene ("Reemay" is one of many brands)

and/or fill the cage with a lightweight mulch (pine straw, hay, straw, deciduous leaves).

This process helps to protect the flower buds along the lower portion of the old stems, which will flower if not killed by cold even if the terminal bud is lost. Leave protection in place until after risk of frost has passed. Be careful when you remove the protective construct so that you don't pop off any buds along the stems.

Protecting Emergent Buds at Winter’s End

Any garden is at risk from a late cold front moving in just when we, and the hydrangeas, thought that spring was finally here. You can either gamble that your losses won't be great, or you can cover the shrubs for the spell of freezing weather.

If you choose to cover your plants, cover them completely to the ground. The ground helps maintain a warmer temperature within the covering.

Use whatever you can get your hands on – garbage cans, large plastic pots, sheets, blankets, fur coats, frost blanket material – and secure the cover to the ground with whatever is at hand – bricks, pieces of firewood, landscape staples, flower pots, children's toys.


 

 

 

 

 

Hydrangea anomala subsp petiolaris iced.

Hydrangeas in the Winter Landscape

What about those bare brown sticks and leftover tawny flowers of hydrangeas in the winter landscape? I personally like how they look, but beauty is in the eye of the beholder. If you feel compelled to tidy up leafless brown stems and faded flower heads by whacking your hydrangea to the ground, remember that you are removing your bloom as surely as would bitter cold or a hard late frost.

There is some thought that the dried flower heads help keep frost from nipping next year's bloom, but you will do no damage if you must prune them – just the faded flowers, no more. As I sit at my desk, one of my winter joys is watching the birds feed on the seeds of the Hydrangea paniculata 'Floribunda' right outside the window. Flashes of color in the winter landscape.

When summer comes and you are surrounded in glorious bloom you'll hardly remember all the trouble you went to. Lift that glass and give yourself a toast. Cheers.

Gene Griffith and Elizabeth Dean
Wilkerson Mill Gardens
9595 Wilkerson Mill Rd.
Palmetto, Ga 30268
(770)463-2400
(770)463-9717 fax
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