Can You Grow Hydrangeas in Hardiness Zone 9?

Hydrangeas are the envy of every garden. Their flowers can add charm and brightness to even the shadiest of areas. Aside from routine maintenance, hydrangeas are also fairly easy to grow. They are well known for their prolific blooms, and are a garden favorite all over the world. So what happens when you want to plant them, but live in a warm climate, like USDA hardiness zone 9?

Hardiness zone 9 covers quite a few different climates. But one thing each of the states that fall into zone 9 have in common, is that they are hot. Whether they are dry, or humid will vary based on your geography, but their temperature ranges are quite similar. So, are you dying to add a hydrangea to your garden, but unsure if it will grow in zone 9?

The good news is that there are many different varieties that are hardy to zone 9. There really is a type of hydrangea for everyone! Read on for tips on which varieties are best, as well as how to keep them alive in a warmer climate.

So, What is Hardiness Zone 9?

USDA zones are different regions in the United States that are classified according to the average low temperature in the wintertime.  Zone 9 experiences average winter lows ranging from 20-30 degrees.

This geographic area is made up of much of Florida, southern Texas, California, Arizona, and along the Gulf of Mexico coast. Zone 9 is considered a year-round planting zone featuring active gardens all year long.

Zone 9 Varieties

Now that you know the general location and climates of the states that run into zone 9, it’s important to look at some of the most popular varieties. Picking a variety that’s a little bit more heat resistant, is a must for these plants. You may even want to consider a variety that can tolerate a bit more sun, depending on where you want to plant them. Let’s take a deeper look!

Hydrangea macrophylla ‘All Summer Beauty’

This variety of the bigleaf hydrangea is covered in large ball shaped flowers. These flowers are sensitive to soil pH, and will have pink or blue flowers depending on the soil acidity. Dark green foliage creates a dramatic backsplash for these flowers.

‘All Summer Beauty’ will grow to 3-5 feet tall and wide. Be sure to save some of these showy flowers, as they are good for cutting. Needs regular watering, a good soaking two to three times a week. Like all big leaf hydrangeas, ‘All Summer Beauty’ thrives in partial sun. About 4-6 hours of sunlight will do.

Hydrangea paniculata ‘Quick Fire’

‘Quick fire’ is an early bloomer for a hydrangea, usually blooming in the beginning of July. The pretty flowers will open white, and turn pink as summer progresses. Growing to 6-8 ft tall and wide this variety would provide good privacy or screening in your yard.

This variety blooms on new wood, making pruning a breeze. In typical panicle hydrangea fashion ‘Quick fire’ loves to be planted in full to partial sun, meaning six hours plus in the sun. Requires regular watering, especially if it’s getting a full day of sun. Be sure to keep your eye on the leaves for drooping and add an additional watering session if needed!

Hydrangea quercifolia ‘Munchkin’

This is a compact plant and is a great choice for smaller landscapes. The flowers will bloom white and turn to pink as they age. The oak leaf shaped dark green leaves turn a pretty mahogany in fall.

This plant grows to three feet high and wide, and would be really nice tucked into a perennial garden. The oakleaf blooms on old wood, and is best pruned in the fall shortly after blooming has ended. Plant in partial sun, giving your plant about four to six hours of sun. Water regularly!

Hydrangea serrata ‘Seaside Serenade Cape May’

This mountain hydrangea variety has large lacecap flowers. The flowers will either be pink or blue depending on your soil pH. As the season progresses the leaves age to a shade of burgundy.

‘Cape May’ is a nice compact plant quickly growing to 3 ft tall and wide. Plant in a border or perennial garden situated in partial sun, and water two to three times a week!

When & Where To Plant

Once you have selected your perfect hydrangea it is time to get planting. Start by digging a a deep hole that’s twice the size of the root ball. Bury the base of the plant as deep as it was in the pot, and no deeper.

Burying the base of the plant can lead to root rot. Adding organic matter like compost is helpful as hydrangeas love rich soil that is well draining. Give the new planting a really good soaking.

Another option is planting your hydrangea in a container.  If you have too much direct sun, and you want to plant any other type of hydrangea but a panicle, this is a great, flexible idea. Follow the same planting instructions.

The best size pot is two feet by two feet. Container gardening is a great option if you have too much direct sunlight, and want to move the container onto a covered porch.

Light Requirements

Hydrangea paniculata can tolerate more than six hours of sun a day. For all other species be sure to situate your hydrangea in partial sun, this is four to six hours of sunlight. Morning sun and afternoon shade is best. Planting on the north side of your home will ensure it receives enough sun and also gets enough shade to thrive in your zone 9 garden.

Maintenance

While hydrangeas can be finicky plants, there are still some commonalities with them when it comes to maintenance in USDA hardiness zone 9. You’ll notice some crossover with zone 10 hydrangea care when it comes to water frequency, and sunlight, since both are in hotter climates.

Let’s take a look at some of the most important aspects of zone 9 maintenance so your newly planted hydrangeas will enjoy a long and happy life in your garden.

Water

Hydrangeas are water lovers, and will require regular deep watering two to three times a week. Avoid overhead watering on the leaves can leave brown spots, or burns. This is due to the water spots they leave behind.

Go with a soaker hose, or drip irrigation if you can. Both are great options for deep watering. If you don’t have irrigation available just aim your hose at the base of the plant, and water away.

Pruning

Take note of what species of hydrangea you are planting as this will be important to keep in mind while you are pruning. Some species bloom on what is called “old wood.” This means it’s growth from the prior growing season.

These species are: macrophylla, quercifolia, serrata, and anomala. Whereas other species bloom on “new wood” which is the growth from the current season. These species are: arborescens and paniculata.

If you are working with a new wood bloomer you really can’t go wrong, it is best to prune in the late fall just after flowering has ended.

The old wood species don’t typically require a lot of pruning. Quercifolia can be left until April before they are pruned, For anomala it’s best to prune after flowering in late June by simply removing the spent blooms.

Fertilizing

Hydrangeas benefit from being fertilized a few times a year. You can use a generic shrub and tree fertilizer, but remember, you generally get what you pay for when it comes to fertilizer quality.

If you notice that your blooms are weak try adding some bone meal to the soil. The bone meal is high in phosphorus, which is needed for flower production.

Color Control

If you were hoping for blue flowers and got pink, or vice versa follow these tips to try to change the color of your blooms!

If you have a bigleaf hydrangea the flowers will react to the pH of your soil. Acidic soils, below 5.5 pH, will favor blue flowers. It allows the plant to absorb more aluminum from the soil. “Sweet soils” with a pH above 6.5 produce pink hydrangea flowers.  Always perform a soil test before amending your soil with anything additional.

If you’d like to enhance the blue of your flowers, aluminum sulfate is the proper choice. It’s available at most garden centers, and the best product to use. Follow the instructions on the package, but a drench of one tablespoon of aluminum to one gallon of water is a safe application rate.

If the plant is dry, water before applying this solution. Applying fertilizer to a dry plant can cause burn both to the leaves and the roots. Applying aluminum should only be used twice a year; once in April and once in May.

For gardeners looking to enhance their reds and pinks, garden lime is the best tool. Find a powder form of garden lime to use at the base of the plant in Apirl, and later in the season, around October.