Hydrangeas are known for their large, showy blooms, which can be found in various colors and arrangements. They are popular ornamental plants, thriving in both gardens and containers (Image Courtesy: Walter Avila).
By John Green, Texas Certified Expert Gardener, Orange TX
Hydrangeas are shrubs that provide large, showy, magnificent blooms when optimal growing conditions are provided. As a gardener, I struggled for many years, attempting to provide the exact growing environment that hydrangea required to not only grow but to thrive! It has been a journey, as our SETX summers are brutal with extreme temperatures, extended droughts, and where winters don’t provide much relief for plants to rebound. Many, many hydrangea have succumbed as I struggled to learn exactly what was required of me to provide them with optimal growing conditions to thrive in our hostile environment. It seems easy enough- simply read the plant tag attached to the shrub and follow the planting instructions! Once established hydrangeas are easy to maintain, requiring little effort other than removing dead limbs, or adding a bit of fertilizer infrequently. Getting them ‘established’ before summer or winters’ arrival can be a bit of a challenge!
They are known for their attractive, sizable flower heads in a variation of colors, shades, sizes, and shapes. Colors include white, red, pink, blue, purple, and many shades in between. Most hydrangea require partial shade during the hottest part of the day. However, there are some varieties which can tolerate full sun, such as panicle type hydrangeas.
Hydrangea Care
Hydrangeas enjoy rich, well-draining, slightly acidic soil. They are ‘thirsty’ plants, requiring frequent, deep watering during summer months. A yearly slow-release fertilizer application in spring is often all that is required. Prune shrubs at the completion of blooming, as this will encourage new growth and more blooms.
Interestingly, Bigleaf and Mountain hydrangeas (Hydrangea macrophylla and serrata) flower color can be manipulated by varying the soils’ pH. Acidic soil (pH below 6.5) promotes blue to purple flowers, whereas alkaline soil (pH above 7) promotes pink flowers. Adding aluminum sulfate to the soil will make the soil more acidic, while adding lime will make it more alkaline.
Growing best in partially shaded areas, hydrangea need space to grow and require amended soil. Our clay soil type, while rich in nutrients, retains too much moisture unless amended with structural components, such as gypsum, compost, composted manure, and other organic amendments to allow for aeration. Choose a planting location in an area which receives approximately five hours of morning sun, and protection from afternoon sun. An area which receives dapple shade the remainder of the day is a perfect site.
Hydrangeas need supplementary (deep watering) weekly, especially during hot, dry periods. Watering every other day is often needed to meet the plant’s hydration requirements. It is important during the first growing season to water deeply and consistently to establish strong roots. Afterward, water when the top inch of soil is dry. Remember, hydrangeas are thirsty plants and don’t like wet feet, preferring an even moisture level.
Apply a yearly slow-release fertilizer following package directions when growth begins emerging in the spring. Scatter fertilizer beneath the entire drip line of the plant (diameter of branches) as hydrangeas have shallow roots.
Hydrangea Types
Hydrangea can be a bit challenging to grow in SETX. It’s important that hydrangeas are planted soon after purchase to avoid common pitfalls associated with planting time. This will ensure they have adequate time to establish themselves with a robust root system before Texas’ blistering summer or frigid winter arrives! The best time to transplant hydrangea is during the fall (while the plant is nearing dormancy), followed by spring as the next best planting time, before blooming begins. Avoid planting during the summer since elevated temperatures reduces the likelihood the plant will expand its root system when transplanted, thus creating a weak plant. It takes about eight weeks of temperate weather for roots to securely take hold. Site selection is paramount, make certain to choose a location where the plant will thrive.
The most common types of hydrangeas that thrive in our area (Zone 8b or 9a) when provided optimal growing conditions:
- Bigleaf Hydrangea (Hydrangea macrophylla)- are classic ‘mophead’ hydrangeas (my personal favorite type) which are known for their large, ball-shaped flower clusters with colors that include pink, blue, and purple. USDA Hardiness Zones: 5 through 9, size: 3 to 6 feet width and height; soil pH: Blue blooms in acidic soil and pink blooms in alkaline soil; blooms on old wood.
- Smooth Hydrangea (Hydrangea arborescens)- have large, cone-shaped flower clusters and remarkably hardy. USDA Hardiness Zones: 4 through 9; size: 3 to 5 feet width and height; soil pH: no effect on color; blooms: on new wood.
- Panicle Hydrangea (Hydrangea paniculata)- late-summer bloomers which change color as blooms mature and are more tolerant of full sun than most other hydrangeas. USDA Hardiness Zones: 3 through 8; size: 10 feet width and height; soil pH: no effect on color; blooms: on new wood.
- Oakleaf Hydrangea (Hydrangea quercifolia)- have oak-like leaves which display beautiful fall foliage that changes to shades of red and purple. USDA Hardiness Zones: 5 through 9; size: 8 feet width and height; soil pH: no effect on color; blooms: on new wood.
- Mountain Hydrangea (Hydrangea Serrata)- have flower blooms in a lace-cap form, with central cluster of tiny flowers that are surrounded by larger flowers. USDA Hardiness Zones 5-9; size: 3 feet width and height; soil pH: no effect on color; blooms: on both old and new wood.
Planting Tips
Hydrangeas prefer moist soil without becoming dry or excessively wet. Prepare the planting area using amendments to create a loamy mixture. Enrich clay soil types with generous amounts of gypsum, composted pine bark, and well-aged manure to build soil structure, improve drainage, and increase aeration.
The planting location must provide hydrangea a bit of shade. They can thrive in both full sun and partial shade conditions but not in SETX! They prefer afternoon shade (partial to complete) to keep them ‘cool’ during summer days.
Hydrangeas are not drought tolerant plants. Large hydrangeas require 2 to 3 gallons of water per week or as temperatures soar.
Pest Resistance
Many new varieties of hydrangeas are resistant to disease and pests, but with SETX humidity there are a few issues for gardeners to keep watch. There are five common pests which enjoy feasting on hydrangeas:
Spider mites are small insects that extract nutrients from hydrangea leaves and blooms. The damage caused by mites are minute holes which have the appearance of freckles.
Aphids are insects that are capable of reproducing at birth, forming colonies (dense, black or green clusters) on the leaf’s underside, where they extract plant fluids which cause leaves to turn yellow and wither.
Japanese and Rose Chafer beetles ‘skeletonize’ hydrangea leaves (flowers too) by eating leaf tissue leaving behind veins.
Powdery Mildew is fungal disease often appearing due to excessive shade or plant overcrowding. It has the appearance of white, powdered material which blocks sunlight and causes leaves to turn yellow, then die.
Leaf Spot is also a fungal disease that appears as dark, wet spots on both leaf surfaces and is caused by excessive moisture on the leaves.
So long for now fellow gardeners, let’s go out and grow ourselves a greener, more sustainable world, one ‘hydrangea’ at a time! For answers to your gardening questions, send me an email: jongreene57@gmail.com.
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