Hydrangeas Not Blooming? 7 Reasons Why and How to Fix the Problem

When your hydrangeas are not blooming around the times you're seeing other hydrangeas with flowers, what's going on? If your plants look generally healthy, the good news is that the problem can usually be remedied and you’ll be able to enjoy bouquets of flowers from your hydrangeas again. Here are 7 common reasons why you'll see hydrangeas not blooming. Once you figure out what's causing your plant not to flower, use the tips in this guide to fill your garden with plenty of hydrangea flowers again.

1. Pruning at the Wrong Time

Pruning at the wrong time of year is the most common reason hydrangeas fail to bloom. Pruning at the right time begins with determining what type of hydrangea you are growing. Here’s a trick: if your hydrangea does not bloom in spring, instead it blooms exclusively in mid- to late summer, it is likely a smooth hydrangea (Hydrangea arborescens) or panicle hydrangea (Hydrangea paniculata) and it produces flower buds in spring. Because smooth and panicle hydrangeas develop flower buds and bloom all in the same growing season, they can be pruned in very early spring.

Hydrangeas that bloom in spring and early summer are likely bigleaf hydrangea (Hydrangea macrophylla) or oakleaf hydrangeas (Hydrangea quercifolia). These hydrangeas bloom from flower buds that formed the previous summer or fall. The best time to prune bigleaf and oakleaf hydrangeas is early summer, right after they finish blooming.

What to do: Prune your hydrangea at the right time and you’ll avoid cutting away flower buds. If you do make a pruning mistake, let the plant bounce back and bloom the following season before doing any more pruning.

2. Winter Injury

Oakleaf and bigleaf hydrangeas form flower buds in late summer and fall for the following spring. The tender flower buds must survive winter to bloom in spring. Blasts of extreme cold and ice damage can kill flower buds. In Zone 5 and below, susceptible hydrangeas flower best when they have winter protection. Hydrangeas in Zone 6 can benefit from winter protection too.

Dry conditions in fall also contribute to winter damage and subsequent lack of flowers. Any type of hydrangea that goes into winter with dry stems and roots is more likely to experience winter injury.

What to do: First, water plants deeply in fall. Protect tender flower buds of susceptible hydrangeas from extreme cold. You can do this by building an insulative cylinder around the shrub in late November, using sturdy stakes and chicken wire or burlap. Fill the cylinder with leaves or straw. Remove the cylinder and leaves in early spring.

3. Deer Damage

Tender stems and fleshy buds will serve as a welcome snack for deer. Hydrangeas are commonly browsed by deer year-round. Winter browsing will eliminate flower buds on oakleaf and bigleaf hydrangeas, while browsing during the growing season will strip away the flower buds of panicle and smooth hydrangeas.

What to do: Protect plants with a barrier or a deer repellant spray. Barriers, such as a fence or netting-style wrap are effective but unattractive in most cases. Deer repellant is invisible and often effective. Sprays must be diligently reapplied after every rain. If deer become insensitive to a particular spray, try a different brand.

4. Too Much Nitrogen

Nitrogen fertilizer promotes deep green leaves but few flowers. Avoid fertilizing your hydrangea with a high nitrogen fertilizer. If you don’t fertilize your hydrangea, it can still be affected by excessive nitrogen because of nearby turf. Lawn fertilizer is often high in nitrogen and can wash into the soil around hydrangeas.

What to do: When fertilizing hydrangeas, choose a product that is high in phosphorus rather than nitrogen to encourage flower production.

5. Late Freeze

A late freeze in spring can kill developing flower buds. Hydrangeas are especially susceptible to a late freeze if the preceding growing days have been mild and the hydrangea is actively growing.

What to do: Pay close attention to the weather forecast in spring. If a late freeze is predicted, protect your plants from frost with sheets or blankets. Use brick, rocks, or anything heavy to secure the cover to the ground.

6. Not Enough Light

Hydrangeas grow best when they receive bright morning light and part shade in the afternoon. Plants growing in too much shade will have few flowers and elongated, floppy stems.

What to do: Move a hydrangea planted in too much shade to a brighter growing location. The best time to transplant a hydrangea is early spring.

7. The Type of Hydrangea

Some types of hydrangeas have a reputation for being finicky when it comes to blooming, even when there is no sign of winter damage, deer have not munched the plant, pruning was done at the right time, and excessive nitrogen is not the problem. One year they unfurl flowers with abandon and the next year only a blossom or two will adorn their leafy stems.

Bigleaf hydrangeas most often fall into this category of unpredictable bloom patterns. Additionally, if you have a potted florist hydrangea, these plants have been forced into bloom out of season (Mother's Day hydrangeas, for example) and are intended to bloom once indoors. These hydrangeas are unlikely to rebloom even if you plant them outdoors.

What to do: Choose a type of hydrangea that generally blooms with regularity, such as panicle, smooth, and oakleaf types.