11 Reasons Your Hydrangeas Aren’t Blooming, and How to Fix it
If you planted some hydrangeas expecting some big and beautiful blooms only to be disappointed, you aren't alone. Hydrangea blooms can stall for a number of different reasons. The good news is many of these problems are correctable. In this article, gardening expert and hydrangea enthusiast Jill Drago looks at the most common reasons your hydrangea may not be blooming and how to fix it.
Contents
I don’t think anyone grows hydrangeas simply for the foliage. Don’t get me wrong, the foliage is really nice… but we are all in it for the flowers! Hydrangeas can come in many different colors. But they are quite possibly the most famous for the beautiful blue hydrangea varieties that sprout stunning blue flowers.
It is so disappointing when the blooming season has come and gone and you didn’t get one pillowy flower on your favorite flowering shrub. The good news here is that once you discover why your hydrangea didn’t bloom, it’s typically pretty easy to remedy.
There are a few reasons that hydrangeas won’t bloom, and some problems are much easier to fix than others. Let’s take a look at some of the most common reasons your hydrangea may not be blooming as it should!
Incorrect Pruning
In my opinion, the number one reason your hydrangea isn’t blooming is because you have started pruning at the wrong time. There are two ways that hydrangeas bloom: new wood, and old wood.
Some hydrangea species bloom on “new wood” which is the growth from the current season. These species are: arborescens and paniculata.
The hydrangea species that bloom on old wood are: macrophylla, serrata, quercifolia, and anomala.
How To Fix It:
If you are working with a new wood bloomer you really can’t go wrong, but it is best to prune in the fall after blooming has finished.
The old wood species don’t typically require a lot of pruning. They are at their best when they are left to grow freely, and pruned only for containment and to remove winter-kill. Quercifolia can be left until April before they are pruned. For Anomala it’s best to prune after flowering in late June by simply removing the spent blooms.
The good news here is that this will only be an issue for one season, so long as you prune correctly (or not at all) this season. Your buds will form properly and will bloom beautifully next year!
Rethink Your Fertilizer
If you are fertilizing too often, or using the wrong type of hydrangea fertilizer, this could be the source of your flowering predicament. Fertilizing with too much of a balanced 10-10-10 fertilizer may be giving your plant too much nitrogen.
Consider your lawn fertilizer as well. If your hydrangea is near your lawn, there is a good chance that there is an overlap with your lawn fertilizer increasing the amount of nitrogen in your soil without your permission. Nitrogen is great for plants, but too much will lessen your blooms, and could promote leggy growth that attracts bugs and other pests.
How To Fix It:
When selecting your fertilizer, look for a flowering shrub specific fertilizer. All flowering plants need phosphorus in order to produce their blooms.
Also, consider adding bone meal can help to alleviate your issue, as this will increase the amount of phosphorus in your soil.
Cold Weather Damage
Hydrangea macrophylla and other old wood bloomers are especially at risk to be damaged by a harsh winter frost, or wintery high winds. This is because these species have already produced their flower buds. Once the temperatures dip below 5 degrees you are in the danger zone of losing the flower buds.
If you live in an area where it is necessary to wrap or over-winter your hydrangeas, spring frost damage can also present itself as another likely scenario. So often spring arrives and we are anxious to get out and start gardening.
Unfortunately it is pretty common for a late spring frost to come and wreak havoc on some of the plants in your garden. A late spring frost will damage the flower buds on your hydrangea. Buds damaged by frost will be brown or black in color and should be easy to spot early on.
How To Fix It:
Be sure to over-winter appropriately if you live in an area with harsh winters. Wrapping your hydrangea with a few layers of burlap will be good enough. Just unwrap in the spring and enjoy!
Consider covering your plant with burlap, or other light breathable fabric when the temperatures are going to dip below freezing, just as you would bring in some of your houseplants. If this becomes a recurring issue, consider leaving your spent blooms on your plant and resist deadheading. This will protect the newly formed buds.
Too Much Shade
Hydrangeas need at least partial shade to bloom. Partial shade is anywhere between four and six hours of sunlight. If your hydrangea is receiving less than four hours of sunlight, you need to rethink the habitat.
There are some hydrangea varieties that can survive in full sun, and other varieties that can live in “mostly” partial shade. But a fully shaded area is not contusive to a growing hydrangea.
How To Fix It:
If it is located under a tree that you are willing to prune, removing some of the limbs would be a great way to get some sun to your plant. However, if this isn’t the case you may need to transplant the hydrangea to a sunnier location.
If you do need to transplant your hydrangea, it is best to do so in the fall, to give the plant time to acclimate before the winter comes, or wait until the spring. Transplanting in the spring will give the plant a chance to get established before the heat of the summer and will help you avoid any transplant shock.
Too Much Sun
Just like your hydrangea can get too much shade, it can also get too much sun. This is one of the most common problems with these popular shrubs. Hydrangea paniculata loves the sun and can tolerate six hours or more. However, the other varieties really prefer partial shade, four-six hours of sun.
Too much sun can stress the hydrangea. You may also notice that the leaves appear to be burnt or scorched. If this is the case, your plant will be conserving energy and skipping the production of flowers.
How To Fix It:
To alleviate this, you will want to transplant your hydrangea to another location with less sun. You can purchase a sunlight monitor at garden centers to check the amount of sunlight in your garden if you are unsure.
Wildlife
If you live in an area with a deer population, the deer could be the reason your hydrangea is not blooming. Hydrangeas that bloom on old wood form buds in the fall and early winter. A flower bud probably looks like a nice snack to a deer in the middle of the winter.
Deer have a tell-tale way of nibbling. They prefer green (new) growth to the old wood. They also rip leaves from the plant, this leaves an appearance of torn leaves. Other critters may be neater about their nibbling, and just grab a bud or two and go.
How To Fix It:
Covering your hydrangea with burlap over the winter will protect them from being eaten. You can also choose to companion plant with other plants that wildlife will likely steer clear of.
Not Enough Water
Hydrangeas are water lovers. If they are not receiving enough water this will cause the plant to stress and go into survival mode, focusing on root and leaf production. Those two systems are what keep the plant alive. Producing flowers takes a lot of energy from the plant, and while flowers do attract pollinators, they are not necessary to the survival of hydrangeas.
How To Fix It:
Ensure that you have well-draining soil. If your soil is sandy, you will want to add some organic material which will help the soil hold on to some of the water.
Mulching is another way to retain moisture at the base of the plant, and also prevent the water from evaporating.
Wrong Hardiness Zone
Something to consider if your hydrangea has not bloomed for an entire season is whether or not the hydrangea in your yard is cold hardy in your area or not. The USDA hardiness rating system breaks the United States up into “zones” that are distinguished by average low winter temperatures.
For example, if you live in zone 6 but the hydrangea at hand is only hardy to zone 7, you may have an issue with your buds dying over the winter due to the cold.
How To Fix It:
If you realize your hydrangea is not appropriate for your particular zone, unfortunately there is not much you can do. However, if you are still shopping for the right hydrangea, be sure to check the tag on the plant to make sure you are making the best selection for your garden.
Your Hydrangea is Too Young
It is very common for a newly planted hydrangea to skip a year of flowering. Depending on the age of the hydrangea when you purchased it, it may be very young. Plants can take a few years to bloom.
How To Fix It:
When hydrangeas are planted in your garden they will invest a lot of energy into creating a strong root system. This pause in blooming should only last a season at most. If you feel confident that the growing conditions are correct for the hydrangea, just continue to water and wait!
Is it a Gift Hydrangea?
Gift hydrangeas are grown in greenhouses in a very controlled climate. Because of this, these types of hydrangeas usually will not rebloom after the first year. This is because the hydrangeas gifted from a florist are simply just not hardy in your area. The roots may be hardy enough to survive, however the top growth (leaves and flowers) will have difficulty surviving the cold.
How To Fix It:
If it’s a gifted hydrangea, consider what may be going wrong with the plant. For mass produced plants, there may be no way to correct it. They could be impacted by some type of pest, or plant disease that’s specific to hydrangeas. They may also just not grow in your hardiness zone (see above).
Garden Pests
When it comes to garden pests and diseases for hydrangeas, the two most common offenders are weeds that attract diseases, and aphids, which are a common type of plant pest.
Weeds may seem like a harmless nuisance, however, if your hydrangea is already stressed and struggling for nutrients and water, weeds will make it worse. Weeds also need water. The roots of weeds tend to be more shallow; they can be successful at robbing the hydrangeas to meet their own needs.
Keep your eyes peeled for an aphid infestation. Aphids don’t nibble on the flowers but they will literally suck the life out of a plant. Aphids will suck plant juices from leaves or stems, leaving those plant materials weak. This can lead to breaking of the stems.
How To Fix It:
Applying mulch at the beginning of the season will help to limit weeds and a weekly weeding session will help.
All of the aphid feeding can cause stress on the hydrangea and prevent blooms from being as prolific as you may like them to be. If you see a large amount of them, sweep them off with your hand.
Final Thoughts
The flowers of a hydrangea are very popular, and most likely the number one reason people plant hydrangeas in their yards. Missing an entire season of blooming hydrangea flowers can feel like such a failure.Try not to stress if your hydrangea didn’t bloom this year. Many of the reasons for the lack of blooms are very easy, and quick fixes!
