How to Prune Bigleaf Hydrangeas for Healthier, More Abundant Blooms

Bigleaf hydrangeas (Hydrangea macrophylla) are one of the most popular types of hydrangeas, recognized for their large lacecap or mophead blooms and lush green foliage. They are grown for their pink, blue, purple, or white blooms, which change color depending on soil pH. 

To enjoy these blooms season after season, proper pruning is essential. Most bigleaf hydrangeas bloom on old wood, meaning the flowers form on stems produced the previous year. Pruning these hydrangeas at the wrong time can remove next season’s flower buds. However, some newer reblooming bigleaf hydrangea varieties, such as Endless Summer, can bloom on old and new wood, offering more flexibility when pruning. 

In general, it’s safest to treat bigleaf hydrangeas as shrubs that bloom on old wood. Ahead, gardening experts share their tips for pruning bigleaf hydrangeas, including proper timing and mistakes to avoid. 

When to Prune Bigleaf Hydrangeas

The best time to prune bigleaf hydrangeas is after they finish blooming in summer. “This gives the plant enough time to produce new growth and set flower buds before fall and winter,” says Jim Putnam, plant expert for the Southern Living Plant Collection. “For most gardeners, light shaping and cleanup should be completed by late summer.”

The Worst Time to Prune Bigleaf Hydrangeas

Never prune bigleaf hydrangeas in late fall, winter, or early spring. “Because most varieties bloom on old wood, flower buds for the next season are already developing on the stems during this period,” explains Kelly Funk, president and CEO of Jackson & Perkins. “Heavy pruning at these times often removes those buds, which can leave the plant with little to no blooms the following summer.”

How to Prune Bigleaf Hydrangeas

When pruning bigleaf hydrangeas, Funk says selective pruning is better than cutting back the whole shrub. “Light shaping, deadheading, and removing older stems immediately after flowering helps maintain the plant’s size and encourages healthier growth,” she says. Below, our experts outline the best way to prune bigleaf hydrangeas. 

1. Remove spent blooms, cutting right above the first set of healthy leaves beneath the flowerhead. 
2. Remove any dead stems, which are typically brittle and won’t show green tissue when lightly scratched. 
3. Remove weak, damaged, or crossing branches to improve airflow and encourage stronger growth. 
4. Shape lightly if needed, but be careful not to overdo it. Hydrangeas perform and look better with a more natural growth habit.
5. For mature hydrangeas, remove one or two of the oldest stems at ground level each year to encourage fresh new growth. 

Pruning Reblooming Bigleaf Hydrangeas 

Reblooming bigleaf hydrangeas are typically more forgiving than traditional varieties because they bloom on old and new wood. “The pruning process stays mostly the same, but gardeners have a bit more flexibility with timing,” says Funk. “Light pruning after the first bloom cycle can sometimes encourage additional blooms later in the season. Even so, it’s still best to avoid aggressive late-season pruning, since preserving healthy stems helps maximize flowering potential.”

Mistakes to Avoid

To ensure your hydrangeas re-bloom next season, our experts warn against making the following common pruning mistakes.

• Over-pruning: Over-pruning can weaken the plant and reduce flowering. “Remember, you can always cut more, but you can’t put it back,” says Damon Abdi, assistant professor of landscape horticulture at Louisiana State University. 
• Incorrect timing: The biggest mistake people make when pruning bigleaf hydrangeas is doing so at the wrong time of year. Cutting bigleaf hydrangeas back too aggressively in fall or early spring often removes the next season’s flowers, Funk notes. 
• Overfertilizing after pruning: Fertilizing bigleaf hydrangeas too frequently after pruning can encourage leafy growth instead of blooms, says Putnam.  
• Using the wrong tools: Abdi warns against using tools with dull blades or that have been used to cut diseased plants, as you risk transmitting these issues to your bigleaf hydrangeas. 
• Removing too much healthy foliage: It’s best to focus your pruning efforts on dead, diseased, or crossing branches, rather than healthy foliage, since the leaves help the plant store energy for future growth and flowering, Funk notes.