Cornell Cooperative Extension in Tompkins County (Published September 2010)
There could be a number of causes for hydrangeas not to bloom. Since we can grow five different species of hydrangeas, some explanations vary based on which type it is.
But first, let’s cover the broad causes. The bush might not be fully developed for blooming. The majority of woody plants don’t bloom until they are rather mature. If a newly planted bush had flower buds when it was in a pot, it might bloom the first year. However, after that, it might not bloom for a year or two as it gets used to the soil in its new position. Instead of flower buds, it is actively forming new roots and branches. There will be a lot more flowers when it eventually starts to blossom again because the bush has indeed “bushed” out!
Sadder still, it’s possible that deer have devoured the flower buds. Where deer have pulled the buds off because they lack incisors, look for rough torn stem ends. Additionally, because all hydrangeas require moisture to thrive, blossoming may not take place if a drought strikes at the incorrect time.
The timing of some hydrangea pruning by gardeners has been off. At this point, determining the species becomes crucial. We have two species that flower on fresh wood (new growth of the current growing season). These include the panicle hydrangea, Hydrangea paniculata, also known as the PG hydrangea, which is frequently seen densely planted in cemeteries, and the native smooth hydrangea, Hydrangea arborescens, which is frequently sold under the cultivar name “Annabelle” and typically has white mophead flowers. Early spring is a good time to prune these two species, and the new growth will bloom later in the summer.
Our other three hydrangea species, however, only flower on aged wood (growth from the previous growing season). The native oakleaf hydrangea, Hydrangea quercifolia, with stunning crimson or maroon fall foliage color, the climbing hydrangea, Hydrangea anomala petiolaris, a fantastic vine for partial shade, and the majority of the highly popular blue or pink bigleaf hydrangea, Hydrangea macrophylla, are included. The flower buds will probably be removed if these plants are pruned in the fall or early spring. It is preferable to prune immediately following blooming, before the new flower buds emerge.
The bigleaf hydrangea has undergone a number of new types over the past few years. They bloom on both old and new wood, hence the name “remontant.” Growing these types will help one prevent a further cause of poor bloom. Flower buds on older, non-remontant types of Hydrangea macrophylla frequently die in our cold winters. However, gardeners who reside in urban areas or close to bodies of water, where the winters are less severe, frequently have success with these types. A winter with a thick layer of snow may also adequately shield the flower buds from the cold in rural areas.
Many customers ask why their hydrangeas aren’t blooming. The primary reasons hydrangeas don’t bloom are incorrect pruning, bud damage due to winter and/or early spring weather, location and too much fertilizer.
There are hydrangea kinds that bloom on either fresh or old wood, or even both. Both new and old wood are the growth of the following year (spring), respectively.
- Consider that this year, you bought a Nikko Blue Hydrangea. For the next year, Nikko’s produce blooms in the fall. Your Nikko is therefore creating blooms this fall that will blossom in the spring.
- Therefore, you wouldn’t want to completely prune your Nikko Blue Hydrangea this fall while you are pruning your perennials. Pruning the Nikko Blue Hydrangea this fall would effectively mean cutting off your hydrangea flowers for the upcoming spring.
- The idea behind Endless Summer, a hydrangea variety that blooms on both old and new wood, is that the plant will set blooms this fall to blossom not only in the spring of the following year, but will also keep producing blooms in the spring of the following year to extend the blossoms into the summer.
- Once more, pruning your Endless Summer hydrangea in the fall would mean removing some of the flowers that would blossom in the spring.
The hydrangea’s plant tag will indicate whether it blooms on fresh wood, old wood, or both. It is typically preferable to wait until spring to prune your hydrangeas. As the plant grows, you’ll see stems that are fragile when bent and lack any leaves. Since these stems are dead and won’t produce any flowers, they should be clipped close to the plant’s base.
The second reason why your hydrangeas aren’t blooming is probably the weather. Buds of hydrangeas are extremely susceptible to cold. Therefore, it is a good idea to wrap your hydrangea for the winter if it is an old wood hydrangea. Keep in mind that old wood hydrangeas establish their blooms for the following spring in the fall. Therefore, you won’t have blossoms in the spring if the fall-produced buds are frozen in the winter.
You can wrap anything with regular burlap. Burlap should be wrapped around the plant and filled with mulch or leaves after the first hard frost and after the hydrangea’s leaves have dropped. In order for the buds to survive the winter and sprout the following spring, the plant receives insulation from this. Never wrap your hydrangeas in plastic. When warmer winter days arrive, the plant cannot breathe since plastic, unlike burlap, doesn’t breathe. As a result, the plant can heated to such high temperatures that it cooks within the plastic and perishes.
The second most frequent weather-related cause hydrangeas do not blossom is late spring killing frosts. We saw really chilly temperatures in April both this year and last year after beautiful spring days. When springtime temperatures drop below freezing, hydrangeas need to be covered with an old beach towel or sheet. Because of the temperature dip, there won’t be any blossoms.
The majority of hydrangeas require at least 3 to 4 hours of light per day to bloom. The best light is in the early morning, midday light is acceptable if it is dabbled light rather than beating sun, and afternoon sun is typically too hot. Check the plant label, though. Newer hydrangea cultivars are being created that can withstand more sun exposure time and sun intensity. A hydrangea in full sun will require much more watering than one in diffused light, so keep that in mind.
High nitrogen fertilizer should not be used to feed hydrangeas. Nitrogen is indicated by the first number on the fertilizer ratio. (The ratio stands for N, P, and K) For healthy leaves and general good growth, some nitrogen (N) is required; however, a ratio of 8-16-6 or any similar combination with a higher middle or phosphorus (P) value is preferred. The growth of roots and shoots is encouraged by phosphorus, which improves the blooming process.
Potash (K), the third element’s last quantity and the lowest ratio, is for plant hardiness. Because hydrangeas prefer acidic soil, they can be fertilized with fertilizers designed for such plants. Hydrangeas only require fertilizing twice a year, once in early spring and once in mid-summer. To avoid root burn, make sure the soil is always moist before applying a fertilizer.
When do hydrangeas begin to bloom?
Grandma was difficult to persuade. Shrubs had to produce and need little care to survive in her garden. Smooth (Hydrangea arborescens) or mophead (Hydrangea macrophylla) hydrangeas in particular were appreciated because they bloom all summer long, unlike many perennials that fade in the heat, need little care, and produce dried pompoms for winter arrangements. Additionally, hydrangeas can bloom in your yard every year because they can be grown in USDA hardiness zones 3 through 9 depending on the variety.
Why isn’t the bloom on my hydrangea?
All varieties of hydrangeas like regular soil moisture and a good deal of moisture. Your plants might not bloom if yours constantly dries out.
In a hot and dry area, bigleaf species plants could require watering every other day.
If you aren’t getting enough rain to meet the two inches of water per week that these plants require, you’ll need to supply additional irrigation.
You can use a rain gauge to determine how much moisture Mother Nature is providing your plants with so that you can provide the extra.
Though less erratic, other species should still be monitored to make sure they have access to enough water.
The leaves will begin to droop and wilt if they aren’t getting enough water, especially during the hottest part of the day.
What is the first year’s growth rate of hydrangeas?
Hydrangeas (Hydrangea spp.) are widespread attractive garden plants with a wide range of bloom colors, including white, numerous shades of blue and pink, maroon, red, and even pale green. There are dozens of species and even more variants of hydrangeas. Depending on the species, some hydrangeas have enormous, rounded flower heads, while others have smaller, flatter, and more delicate blossoms. Plant hydrangea shrubs in the fall or early spring to give them time to develop a strong root system. With an average annual growth of two feet or more, hydrangeas are quick-growing plants. Be aware that both humans and animals are poisoned by the plant.
How do hydrangeas appear before blooming?
The tips of the stems that Big Leaf and Mountain Hydrangeas generated last year are where they blossom (old wood). Some of those same stalks also have flowers on the sides (new wood). Still other plants bloom on stems they create this year (new wood). The old wood plants need to cling onto those blooms for approximately nine months, through late fall, winter, and early spring, beginning around August 1. Therefore, if you prune the stems of your old wood plants after August 1, you run the danger of losing the flowers that will bloom the next year.
No Pruning After August 1st
First rule: don’t prune them until the buds start to show, which may not be until June. The buds resemble little broccoli heads. Then you will know which stems and buds successfully overcame their seasonal obstacles.
If your shrub isn’t blooming, the first thing you should look at is whether or not you pruned it back. These plants often only require trimming to remove damaged, diseased, or dead stems.
Are hydrangeas water-intensive plants?
Although the hydrangea’s leaves and flowers seem delicate, little careful care is actually needed for them. Everything you need to know about caring for hydrangeas is provided in these recommendations.
- Over the course of the growing season, water at a rate of 1 inch per week. To promote root growth, deeply water three times each week. All varieties of hydrangeas benefit from constant moisture, but bigleaf and smooth hydrangeas need more water. To water thoroughly while keeping moisture off the flowers and leaves, use a soaker hose. Hydrangeas won’t wilt as much if they are watered early in the day on hot days.
- To keep the soil around your hydrangeas cool and moist, add mulch. Over time, an organic mulch decomposes, supplying nutrients and enhancing soil texture.
- Apply fertilizer according to the type of hydrangeas you have. Every variety has varied requirements and will profit from applying fertilizer at various times. A soil test is the most effective tool for determining your fertility requirements.
- In March, May, and June, bigleaf hydrangeas require numerous mild fertilizer applications.
- Two applications in April and June work best for oakleaf and panicle hydrangeas.
- The only time smooth hydrangea plants require fertilizing is in the late winter.
- By selecting cultivars with resistant characteristics, you can avoid pests and diseases. Hydrangeas can have leaf spots, bight, wilt, and powdery mildew. Although they are uncommon on hydrangeas, pests might arise when the plants are under stress. Aphids, leaf tiers, and red spider mites are examples of potential pests. Your best line of defense is to properly care for hydrangeas.
Are hydrangeas sun-sensitive?
Many people believe that hydrangeas must be grown in a shaded area. While it is true for certain species, some hydrangeas require full sun to grow to their utmost potential and produce the finest blooms. These plants even flourish in sunny locations.
Knowing which exact hydrangea varieties you can grow in the sun or shade is crucial because there are numerous variants available. Here are some of our top choices for perennial hydrangeas in Iowa, both for sunny and shady locations.
How can I speed up the growth of my hydrangea?
Smooth hydrangeas (Hydrangea arborescens), which get their name from the texture of their huge leaves, are more well-known for their massive, spherical, white flower heads. The most popular type, “Annabelle” (also known as Snowball Bush), was identified as coming from Anna, Illinois, by a horticultural expert in the 1960s. The ‘Annabelle’ hydrangea displays large, pure-white blooms that gradually turn green. A more recent cultivar, Invincibelle Spirit, blooms pink rather than the usual white. The smooth hydrangea, which is native to parts of North America, starts blooming in late June and keeps periodically flowering all summer long. In zones 4 through 9, it thrives in sunny or slightly shaded environments.
How to Get More Smooth Hydrangea Flowers:
- If the soil is damp, grow smooth hydrangeas in full sunlight. (Spots that occasionally dry out benefit from partial shade.)
- In droughts, especially in the sweltering summer, water them.
- soil amendment using organic matter (such as compost).
- In the early spring, soon as new growth begins to appear, trim back stems.
Do hydrangeas regrow each season?
Hydrangeas will indeed reappear each year if they do not perish during the winter. Though not all gift hydrangeas are bred to grow especially winter-hardy. Thus, hydraneas occasionally do not endure the winter. However, most hydrangeas will reappear each year.
Do hydrangeas grow in numbers?
When clipping hydrangeas to propagate the plant, when you cut and where you cut are two important considerations. The optimal period is when new stems first begin to stiffen, which is in late spring and early summer. New stems are prone to bending but are also easily snappable, and these cuttings have a strong growth tendency.
Cut a green, fragile branch that is 5 to 6 inches long and that is not in bloom. Make sure the cutting has at least three sets of leaf nodes—the points at which a leaf emerges from the branch—but only cut just below a leaf node. The bottom two leaf nodes’ lower leaves should be removed. Reduce the biggest leaves by around 50% in size as well.
The procedure can be sped up but is not required by dipping the cutting in rooting hormone. Place it with one or two nodes submerged in wet vermiculite or sterile medium in a well-drained container.
Fill the pot with water, cover it with plastic, or set it inside a plastic container with a lid to create a mini-greenhouse or humidity dome. Plant them after four to six weeks, when a strong root system has developed. Keep your cuttings away from the sun’s harsh rays.