Hydrangea not Blooming? Here's what to do

Reader William Stovall asks: “I have a seven-year-old oakleaf hydrangea in a shaded location. It grows a lot of healthy foliage that I have to prune regularly, but my hydrangea is not blooming. It bloomed only once or twice.  Why do you think that is?”

It’s all about the timing when pruning this and other hydrangeas.

Oakleaf hydrangeas produce flower buds the year before they bloom. Keep pruning to a minimum to maximize the floral display. Remove only the damaged and wayward branches each year as needed. This helps control the plant’s size while encouraging it to bloom.

Heavy pruning stimulates growth and results in a larger plant that needs additional pruning. Selective pruning leaves you with more stems with intact flower buds for a better bloom the following year.

Prune like a pro: Study the shape of the plant before making any cuts and make sure you always use clean, sharp tools. Avoid overpruning by cutting only one-fourth to one-third of the canopy per year.

Climbing Hydrangea Not Blooming

“My six-year-old climbing hydrangea has never bloomed,” writes reader Alyssa Kadyk. “It’s 15 feet tall and spread out over a trellis. How can I encourage blooming?”

You’re definitely not alone. A hydrangea not blooming is a common issue among gardeners who grow climbing hydrangeas.

As you discovered, these plants take a long time to establish and start flowering. Avoid high-nitrogen, fast-release fertilizers that encourage leaf and stem growth but discourage flowering. Water plants thoroughly as needed and use a low-nitrogen, slow-release fertilizer if you feel your plants need a boost. Beautiful blooms will grow as a reward for your patience.

Protect Hydrangeas in Winter

“My hydrangeas are about 15 years old and have bloomed only once,” reader Loretta McClincy writes. “I feed them and mulch them with pine needles and leaves in the winter. What am I doing wrong?”

Most bigleaf hydrangeas (Hydrangea macrophylla), those with pink or blue flowers, produce blooms only on the previous season’s growth. They are also known as mophead hydrangeas. Flowers bloom pink in alkaline soil and blue in acidic soil. If they die back to the ground or are pruned to the ground in late winter, they will not flower.

In your climate, you need to protect the future flowering stems from the cold. Try encircling the plant with four-foot-tall hardware cloth. Sink it several inches into the ground to keep out rabbits and voles, then fill with weed-free straw or evergreen boughs to insulate the plant. Wrapping the fencing with burlap or weed barrier will add another layer of insulation.

You might also consider putting evergreen boughs or weed-free straw over the plants after the ground freezes. These mulches provide better insulation than leaves. In spring, remove the mulch and wait to see if there’s any growth on the stems. This is the growth that will flower. You should prune off only the dead portions of the stems.

If you’re growing one of the repeat-blooming bigleaf hydrangeas, make sure the soil is moist and fertilize with a low-nitrogen organic fertilizer once in spring. These varieties are supposed to flower on old and new growth with proper care.

Many Northern gardeners have switched to hardier panicle hydrangeas, whose flowers start out white and fade to pink. Moisture and proper fertilization are the keys to success with these.