Every year we hear from customers that they have beautiful,healthy,and lush Hydrangeas which won’t bloom. There are several factors which can contribute to your Hydrangea’s lack of blooms, including frost damage, too much fertilizer, and improper pruning. The most common reason is pruning, either too much or at the wrong time. Here is some information on how to properly prune your Hydrangeas, as well as other possible contributors to your shrub’s lack of blooms.
To prune or not to prune: that is the question
Knowing how and when to prune your Hydrangea can be confusing. As a rule of thumb little to no pruning is a good habit to get into with Hydrangeas. In fact, lack of flowers and floppy stems is usually due to over-zealous pruning. Although the plant’s dead stems in winter makes the compulsion to prune difficult to ignore, these woody plants can live long, floriferous lives without ever needing a haircut. In our experience it is best to prune very rarely if you want a Hydrangeas true beauty to shine through. Choose a place for your Hydrangea that gives it enough space to grow, around 4-5′ and 5′ wide( depending on variety). Bloom size and quality will continue to be consistent for many years with little pruning. Hydrangeas can handle a bit of pruning though, and sometimes you might want or need to cut them back a bit to increase its size and vigor. The important thing to remember about pruning your hydrangea is that the variety of hydrangea is very important in terms of knowing when to prune and how much.
Determine which pruning group your hydrangea belongs to:
There are three types of Hydrangeas in terms of how they bloom: those that bloom on old growth, those that bloom on new growth and then there is the Endless Summer series which bloom on old and new growth. Hydrangeas that bloom on old growth should only be pruned after flowering, and clipped just below where the bloom was. Hydrangeas that bloom on new growth should be pruned in early spring or as they are going dormant in fall. Endless Summer series should be pruned like those that bloom on old growth. Understanding the different varieties of Hydrangeas and their specific needs is the best way to ensure lots of flowers.
If you are not sure on which variety of Hydrangea you have in your garden, we have a few tips to determine when to prune.
When did it flower?
Hydrangeas that bloom on old growth generally begin blooming in early summer and finish by midsummer, though sporadic blooms may appear afterward.
Because they need to grow and set buds the same year that they bloom, shrubs that flower on new growth generally start blossoming later than old-growth bloomers, beginning in midsummer and continuing until the first frost. These shrubs are forgiving if pruning is not done at a certain time as long as you avoid pruning when the flower buds are opening.
If your Hydrangea bloomed from early summer to fall in previous years you most likely have a Hydrangea from the Endless Summer series.
If you can’t remember when it bloomed, what color and shape were the blooms?
If your plant produces big pink or blue flowers,treat it as an old wood blooming Hydrangea.
If its flowers are round and white , treat it as a new wood blooming Hydrangea.
Finally, if the plant has large, conical flowers, which are often white but may also be green or pink, you can treat it as new wood blooming Hydrangea.
When and how to prune:
Old Growth Hydrangeas- Hydrangea Macrophylla
These shrubs form next year’s flower buds in late summer or early fall. To reduce the risk of removing these buds, prune just as the flowers begin to fade. Often, the earlier you get it done after bloom, the quicker the shrub can recover, producing more and larger blooms next season.
Don’t prune these hydrangeas to the ground in late fall or early spring! Doing so removes all of next year’s flower buds.
- To tidy up, remove old blooms. Gardeners who want to maintain a tidy appearance can snip off spent blooms just below the flower head and remove any wayward or straggly canes at the soil line.
- To improve vigor, remove the oldest canes. When a Hydrangea gets old and woody, it can produce smaller blooms. Regular removal of a few of the oldest canes at the soil line can keep the shrub vigorous, producing large and abundant flowers. The same method can keep a shrub from getting too tall by targeting the tallest canes for removal.
New Growth Hydrangeas- Hydrangea Arborescens & Hydrangea Paniculata
- To get bigger flowers, cut them all the way back in late winter or early spring. Hydrangeas will produce much larger blooms if pruned hard like this each year,but depending on plant variety this can lead to a floppy looking Hydrangea. Many gardeners opt for smaller blooms on sturdier stems.
- To reduce flopping, leave a framework of old growth. Some hydrangeas’ branches often fall over under the weight of their blooms, especially after overhead irrigation or after a good rain. One way to alleviate this flopping is to cut the stems to a height of 18 to 24 inches to provide a sturdy framework to support new growth.
Endless Summer Series
- Since these plants set buds on old and new growth they are fairly forgiving. It is recommended to prune them like old growth blooming varieties. Remove spent blooms as they fade to encourage blooms for the next season.
- If you forget to remove spent blooms in fall and choose to prune in spring you can do so, just remember you are cutting off possible blooms for that season. You will still get blooms in late summer as they will produce blooms on new growth.
But I didn’t prune last fall or this spring and I still don’t have blooms!
If you have not pruned your Hydrangeas and still have no blooms here are a few more things to look at:
- New plantings:If you have just planted your Hydrangea in the last year or two it is not uncommon for them to have little to no blooms. New plantings are trying to produce a good root system to survive and will often focus on this before blooms. Give your Hydrangea a year or two to establish its root systems.
- Location: Hydrangeas will not produce showy,lush blooms in heavy shade. If you have a part sun,part shade area you could try Annabelle or Invincibelle, which tolerate more shade. If your Hydrangea continually fails to bloom and it does not receive 4 hours of sun you may want to consider relocating it to a sunnier location.
Hydrangeas prefer moist locations,especially in the first 2 years of planting. Plant in an area that does not get too dry during our hot summers, otherwise make sure it is an area where you can get water to daily.
It is best to choose a protected area that does not receive too much winter winds. For Hydrangeas that set blooms on old wood harsh winters, like the one we just witnessed, can damage blooms for the following spring. If you do have an open area you may want to consider winter protection.
- Fertilizer:Generally when we speak about plants not blooming we immediately think we need to feed them. With Hydrangeas this could be the opposite. Too much fertilizer can cause a Hydrangea to focus on growing nice leaves rather than blooms. Use a well balanced liquid fertilizer, like a 10-10-10 once in May and again in June/July. You can also choose a slow-release fertilizer and use once in May.
Hydrangeas can be very forgiving plants, even with improper pruning, winter-kill, and over-fertilizing they can produce large blooms in the following season. Follow our guidelines and be patient with your hydrangea in the season it doesn’t bloom, next year you should see an amazing showing!