When you see a shrub covered in masses of large fragrant flowers, you want to grow that shrub. When the flowers last all summer long, and different varieties bloom in shades of pink or blue, lavender, white, and even lime green, it’s especially desirable.
You plant it carefully and try to meet all the cultural conditions these plants require. However, it’s terribly disappointing when summer comes and goes, and there are no flowers.
You thought you did everything right. So why aren’t your hydrangeas blooming?
While different varieties can have different needs, the lack of flowers is occasionally caused by circumstances beyond our control. Other times it’s because you are trying to grow the “wrong” hydrangea in the wrong spot or are caring for it in the wrong way.
Let’s look at some of the common reasons hydrangeas won’t bloom. And what you can do to encourage flowering.
1. It Was a Gift
In the spring, just in time for Easter and Mother’s Day, florists offer beautiful potted hydrangeas. These gorgeous plants make the recipient say “Wow! Thanks!” and ideas of planting them in the garden form, imagining they will grow large and form flowers in that beautiful blue color for years to come.
Sorry. These gifts are grown in greenhouses and are heavily manipulated for maximal bloom. Like florist mums, forced tulips, poinsettias, and potted mini rose bushes, they are only meant to be enjoyed for a short time. Enjoy them as you would cut flowers and when the flowers fade, you can compost them without guilt. They won’t flower again and won’t survive being planted in the garden.
2. It’s Too Early in the Season
Don’t worry if the same variety you bought last spring is in bloom right now at the garden center, but yours has barely leafed out.
Many garden plants are grown in greenhouses and are forced into bloom for quick sale in the spring. While it’s nice to see what a plant’s flowers will look like when you buy it, know that after it’s planted, it will bloom in the following seasons at its proper time. A little patience is all that’s needed here.
3. It’s Too Young
Newly planted hydrangeas spend their first year or two growing a robust root system. Reliable flowering happens after they are established. For example, a climbing hydrangea can take as long as five years to produce flowers! Give your new shrub time to get settled.
4. It’s Not Hardy in Your Area
Most local nurseries and garden centers will sell only plants that are hardy in your zone, but some do not. And if you bought your plant through a website, you might be buying something that won’t thrive in your area. For certain species, the rootstock and the shrub itself may be cold-hardy, but the flower buds may not. They can be killed by freezing temperatures.
Know your zone and read the plant tag. This is when it pays off to visit a good nursery – the staff there can answer your questions and help you choose the right plants for your garden.
If you have a hydrangea that is out of its zone, you can protect it by planting it in a sheltered area. You can build chicken wire cages filled with fallen leaves or wrap your shrubs in burlap to protect next year’s flower buds from freezing temperatures. Remove these covers in early spring, but keep an eye on the forecast and cover the shrub with a blanket or sheet when frost is predicted.
5. It’s Been Browsed by Deer or Rabbits
These critters can bite off next year’s flower buds when they snack on your plants. If you see tracks, droppings, bitten stems, and chewed leaves, you can assume deer or rabbits have been lunching on your hydrangeas.
Deer rip and tear leaves from stems, often taking the upcoming flower buds with each bite. Rabbits chomp stems on a strong, sharp, clean diagonal, which prunes off the flower buds.
You can build physical barriers to keep these critters out. You can also protect your plants with products like Plantskydd and Liquid Fence. These products will need to be reapplied occasionally. Read the label and follow the instructions carefully.
6. Insects and Diseases
If your plant had a major disease or insect problem last summer, it might be weakened to the point where it has no energy for flower production.
Be sure to scout for diseases and insects during the growing season and take care of any problems right away.
7. Too Much Sun? Too Much Shade?
These shrubs prefer morning sun and light afternoon shade. Hydrangeas, especially oakleaf and macrophylla varieties, may be too stressed to flower if planted in full sun.
Low light levels also discourage flowers. Paniculata varieties can take up to 6 hours of full sunlight. Other varieties need less, about 3 to 4 hours of the morning sun, but none thrive in full shade.
8. Not Enough Water
A lack of adequate moisture stresses a plant and can hinder flowering. Hydrangeas prefer moist, well-drained soil. During dry spells, you will need to give your shrubs 1 to 2 inches of water per week during the summer. A layer of mulch around the root zone will hold in moisture.
9. Improper Fertilization
All plants need fertilizer, right? Not always.
Hydrangeas often do just fine with no added fertilizer. A fertilizer high in nitrogen encourages large, robust, healthy leaves at the expense of flower formation.
Test your soil before you fertilize and only apply a nitrogen fertilizer if the test reveals this element is lacking. A good fertilizer for flower production will have a high middle number in its N-P-K analysis, indicating high amounts of phosphorus.
They prefer slightly acidic soil (although they are adaptable) so if your test reveals a high soil pH, look for a fertilizer formulated for acid-loving plants.
You might hear recommendations for adding coffee grounds or epsom salts to the soil. This practice is not recommended. It is better to put the coffee grounds in your compost bin and when the compost is finished, put some around your plants. Leave the epsom salts for your bathwater for a relaxing soak after a hard day working in the garden.
10. Late Spring Freeze or a Cold Harsh Winter
This is the second most common reason hydrangeas won’t bloom. If the flower buds are killed by freezing winter temperatures or late spring frost, they will not bloom. This happens to varieties that bloom on old wood.
If your bush has bloomed reliably in years past, and this past winter was very cold, or there were a series of late frosts, your plant may have lost its flower buds.
11. Improper Pruning
This is the number one reason they don’t bloom – pruning at the wrong time. For many varieties, the following year’s flower buds are formed in late summer or fall. If you prune after the buds have set, you could accidentally cut them off. You won’t have any flowers next summer.
Prune varieties that bloom on old wood (the stems that grew last year) right after they have finished flowering.
- Bigleaf or French (Hydrangea macrophylla), both mophead and lacecap, can have a third of the oldest stems removed all the way to the ground in autumn. This keeps your plant vigorous. Don’t prune their tops.
- Mountain (H. serrata) are treated just like bigleaf species.
- Climbing (H. anomala, formerly called H. petiolaris) only needs pruning to remove dead or damaged stems or if you need to direct its growth.
- Oakleaf (H. quercifolia) also doesn’t need pruning. Only remove any dead and broken branches.
Prune varieties that bloom on new wood (the growth that will happen this year) in late winter or early spring.
- Smooth (Hydrangea arborescens), like Annabelle, can be cut all the way to the ground in early spring. In colder zones, these shrubs die back and are often treated like a hardy perennial. In warmer zones, cut them to the ground before they start leafing out because these old stems won’t produce any flowers.
- Panicle (H. paniculata) should be pruned in late winter or early spring. Up to one-third of the old stems can be removed to the ground. Older varieties of this shrub can get large, but you can cut back the top and not lose next year’s flowers. Tree forms should be pruned every year.
Reblooming hydrangeas bloom on both old and new wood. The Endless Summer series and the Forever & Ever series have lots of beautiful varieties. The only pruning they ever need is to have their flower heads removed and dead or weak stems cut to the ground.