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Proven Winners® ColorChoice Flowering Shrubs

Hydrangeas for the South

Limelight Prime hydrangea with large blossoms

What you need to know about growing hydrangeas in hot climates

Whether your tastes tend toward the classic pink, purple, or blue blooms of big leaf or mountain hydrangea (H. macrophylla and H. serrata), the giant cones of panicle hydrangea (H. paniculata), the eye-popping orbs and discs of smooth hydrangea (H. arborescens), or the four-season beauty of oakleaf hydrangea (H. quercifolia), here you'll find everything you need to know to pick the right hydrangea for your unique climate - and your taste.

While the South's climate presents lots of opportunities to grow beautiful hydrangeas, it also poses some challenges that you should know before picking and planting a hydrangea.

In your case, your concern about success with hydrangeas isn't so much how much cold they can take, but how much heat and humidity they can tolerate and still earn pride of place in your garden or landscape.

With a little know-how (which we're going to give you here), you'll not only be able to pick the perfect hydrangea for your climate, but care for it like a professional horticulturist.

Big Leaf & Mountain Hydrangeas (H. macrophylla + H. serrata)

Maximum Heat Tolerance

Big leaf and mountain hydrangeas are heat tolerant through USDA zone 9. They are cold hardy down to USDA zone 4 or 5, depending on the variety.

Native Range

Japan and China. Big leaf hydrangeas (Hydrangea macrophylla) occur naturally in coastal areas; mountain hydrangeas (Hydrangea serrata) occur in mountainous regions. These hydrangeas may also be called florist hydrangeas, hortensia, or mophead hydrangeas.

Features

These are the classic plants that come to mind when you think of hydrangeas: large orbs of blue, purple, or pink flowers. Their foliage is thick, dark green, leathery, and usually quite shiny. Their stems are typically spotted but may be red or black, depending on the variety. Flowers may be mophead or lacecap. Blooms on old wood, though reblooming varieties bloom on both old and new wood. Deciduous.

Light Requirements for the South

Shade during the hottest part of the day is imperative in hot climates. They can take a bit of morning sun, which will help plants develop strong stems and more abundant, more colorful flowers.

What to expect from big leaf & mountain hydrangeas in the South

  • They will begin to bloom much earlier than in the North – generally, late spring as opposed to summer.
  • Reblooming varieties like the Let’s Dance series will put on their new wood buds sooner, and bloom for much longer.
  • Flower color may be less vivid during periods of hot weather, particularly if night temperatures are high. However, bright, true colors will return will it gets cooler.
  • Plants will tend to get taller and wider due to the longer growing season and milder winters.

Growing Tips

  • Avoid pruning big leaf and mountain hydrangeas – cutting them back will impair current or future blooming. If they need to be pruned, cut them after they bloom in spring/summer, but know they may skip rebloom or the following season’s bloom.
  • A good 2-3″ layer of shredded bark mulch or pine straw is imperative for the delicate, shallow roots of these hydrangeas. 
  • While big leaf and mountain hydrangeas are generally disease resistant, powdery mildew can develop in high humidity. Avoid wetting the foliage and provide good air circulation to mitigate.

Oakleaf Hydrangea (H. quercifolia)

Maximum Heat Tolerance

Thrives in all but the hottest Southern climates, growing readily through USDA zone 9.

Native Range

Southern and Southeastern US, from the Carolinas to Arkansas and South from Louisiana to the Florida panhandle.

Features

Large, conical flowers in early summer that are white with some varieties aging to a nice pink. Oakleaf hydrangea derives its name from its large leaves that resemble those of oak trees. The foliage turns appealing shades of burgundy and red in autumn, making it one of the best hydrangeas for fall color. Peeling bark in winter provides interest even during the off-season. Flowers are generally lacecap, but some mophead types can be found. Blooms on old wood wood. Deciduous.

Light Requirements

Oakleaf hydrangeas are very shade tolerant, though deep shade will hinder blooming and fall foliage color. Ideally, plant with a few hours of sun and shade during the hottest part of the day.

What to expect from oakleaf hydrangeas in the South

  • Will bloom earlier than in the North
  • Plants will generally attain larger sizes
  • Varieties that age to pink may not develop the best color
  • Fall color occurs later

Growing Tips

  • Plant in moist but well-drained soil; established plants show some drought tolerance.
  • Prefers acidic soils and may turn yellow in alkaline conditions.
  • Leaf spot may develop but does not harm or set back the plants.
  • Blooms on old wood – best left unpruned, though branches may be selectively pruned to manage width or develop a more dramatic habit.

Climbing Hydrangea (H. petiolaris + H. hydrangeoides)

Maximum Heat Tolerance

Climbing hydrangeas are heat tolerant through USDA zone 9.

Native Range

Japan and Korea. Though Hydrangea petiolaris is known as "climbing hydrangea," the closely-related Hydrangea hydrangeoides (formerly known as Schizophragma hydrangeaoides) is known as Japanese hydrangea vine.

Features

These two climbing hydrangeas are woody vines that scramble up trees or structures using clinging aerial rootlets. White lacecap flowers appear in late spring/early summer. Blooms on old wood. Deciduous.

Light Requirements

As these species grow up trees in their native environments, they are well-suited to shady conditions and look their best under high canopies that let light through to the plant.

What to expect from a climbing hydrangea in the South

  • Faster growth than in the North
  • Will get established more quickly, leading to earlier blooming
  • Larger flowers, earlier in the season

Growing Tips

  • Provide a sturdy, permanent structure for these vines
  • Aerial rootlets cling best to rough textures, like masonry or tree bark.
  •  Most likely will not begin to cling on its own until its second season after planting.

Panicle Hydrangeas (H. paniculata)

Maximum Heat Tolerance

Generally speaking, panicle hydrangeas are heat tolerant through USDA zone 8. However, 'Limelight' has proven heat tolerant through USDA zone 9. Testing is ongoing with the other Proven Winners ColorChoice panicle hydrangeas.

Native Range

Japan, Taiwan, China. Also called hardy hydrangeas, peegee hydrangea, P.G. hydrangea.

Features

Big, conical blooms are reminiscent of ice cream cones or footballs. They start white or green and age to shades of pink, red, and burgundy. Plants come in a range of sizes, from very small (2'/.6m) to 10'/3m+. Very popular for cut flowers, both fresh and dried. Blooms on new wood. Deciduous.

Light Requirements

Panicle hydrangeas are the most sun and drought tolerant of all hydrangeas. However, in the South, afternoon shade is recommended for best flowering and the best potential for pink/red color to develop later in the season.

What to expect from panicle hydrangeas in the South

  • Though plants will flower abundantly, blooms may not develop the rich pink-red colors you see in photos, particularly if night time temperatures are high.
  • Plants will generally get larger, faster, so should be pruned accordingly.
  •  High humidity in the summer often reduces water needs; panicle hydrangeas are very sensitive to root rot in wet soils so if you see wilting, don’t automatically assume water is needed. Check soil moisture manually first. 

Growing Tips

  • If blooms are going brown instead of aging to pink/red, this may indicate the plant is not getting enough water or that night time temperatures are too high for color to develop.
  • Does not tolerate wet soil – monitor soil moisture carefully.
  • Some sun is recommended for strongest stems and best flower development. 

Smooth Hydrangeas (H. arborescens)

Maximum Heat Tolerance

Smooth hydrangeas are heat tolerant through USDA zone 8. They may be able to be grown in cool parts of USDA zone 9 with enough shade and well-drained soil.

Native Range

This North American native occurs naturally from New York west to Iowa, and from Louisiana east through northern Florida. This hydrangea is also known as wild hydrangea, hills of snow hydrangea, wild seven bark, or 'Annabelle' hydrangea (which refers to the specific variety 'Annabelle', released to the market in the 1960s).

Features

Large, rounded blooms on thin, elegant stems in early summer. Though for years, white was the only option, now pink, mauve, and lime green varieties can be found. In nature, flowers are lacecap but nearly all popular garden varieties are mopheads. Blooms on new wood. Deciduous.

Light Requirements

Shade during the hottest part of the day is imperative, though a bit of morning sun or some filtered light will result in bigger blooms, stronger stems, and in the case of the colorful varieties, more vivid color.

What to expect from smooth hydrangeas in the South

  • Earlier bloom time than in the North
  • Plants will reach a larger size
  •  In too much sun and/or high humidity, blooms can turn brown in center.
  • For the strongest stems, cut back by only about half the total height. Do not cut to the ground.

Growing Tips

  • Good drainage is essential for success with smooth hydrangeas. Avoid wet conditions and monitor moisture carefully, especially during high humidity, when plants aren’t using as much water.
  • Makes an excellent cut flower
  • Lacecap varieties like Invincibelle Lace hydrangea attract pollinators.

Frequently Asked Questions

Look for these hydrangeas in the distinctive white container at a garden center near you.
Quick Fire Fab hydrangea in a pot
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