When Do Limelight Hydrangeas Bloom In Ohio

Hydrangeas come in a variety of flower hues and sizes and are comparatively simple to grow. Hydrangeas have become much more well-liked in recent years. They can collectively bloom from May through the fall and have characteristics that draw attention through the early winter. Their name, hydrangea, is derived from the Greek words “hydor,” which means “water,” and “aggeion,” which means “vessel,” which refers to the seed capsule’s shape and the plant’s affinity for moisture (Oregon State University, 2015). Here are some images of typical Ohio hydrangeas.

Selecting Hydrangeas

This fact sheet will assist Ohio gardeners in choosing hydrangeas based on site requirements, plant management requirements, and the capacity to draw pollinators. Additionally, gardeners will be able to contrast the maintenance requirements, flowering times, and other distinctive traits of several hydrangea species. There are six hydrangea species that are frequently planted in Ohio. Based on their similarities, the bigleaf (Hydrangea macrophylla) and mountain (Hydrangea serrata) are going to be addressed together in this fact sheet.

The cultivars covered in this data sheet are based on observations made over the course of multiple growing seasons and documented in the literature. There is simply not enough space or local research expertise to properly detail the other cultivars that aren’t listed or addressed, even though they will grow in Ohio. Each year, there are too many brand-new hydrangea varieties to cover all the options for successful planting in Ohio. To choose the ideal cultivar for their garden, growers must continuously notice new varieties and conduct fundamental study. To further assist gardeners in choosing plants for their gardens, a chart summarizing the species described is supplied at the end of this data sheet.

Hydrangea macrophylla “Double DelightsTM Perfection” (top left), Hydrangea quercifolia “SnowflakeTM” (bottom left), a honey bee on a Hydrangea paniculata “Great StarTM” with extended petals, and Hydrangea arborescens “Invincibelle Spirit” are examples of common hydrangeas planted in Ohio.

Choosing the Right Plant

When selecting the best plant for the landscape, there are numerous hydrangea traits to take into account. To begin, there are two key characteristics that are very significant for hydrangeas: bloom durability and the capacity to draw pollinators.

In some areas of Ohio, hydrangeas might not bloom every year due to the cold climate or bad trimming practices. Whether the buds are developed on old or new wood is the challenge.

  • Old wood is growth from the previous year. The previous year, typically in August, the buds for the current year’s blooms were created. There will be little to no bloom the next year if these varieties are pruned or cut down in the fall.
  • The growth from this year is referred known as “new wood.” The year before they bloom is when the buds are set on cultivars that bloom on fresh wood. In the very early spring or the fall, these plants can be trimmed.
  • Bigleaf hydrangeas (H. macrophylla varieties) blossom on old wood and lose their flower buds in temperatures that are below USDA hardiness zone 5. Based on a 30-year temperature average, the USDA has created hardiness zones that stretch from northern to southern Ohio. The USDA hardiness zones for Ohio range from 5b, where low temperatures are typically between 15 and 10 degrees Fahrenheit, to 6b, when they are typically between 5 and 0 degrees Fahrenheit (USDA, 2012). Ohio regularly experiences colder temperatures than these because this map is based on a 30-year average.
  • Some mountain (H. serrate) and bigleaf (H. macrophylla) varieties can bloom on both old and young wood. The likelihood of successful blooms each year is increased for gardeners by investing in a plant that blooms on both old and new wood. Giving winter protection will further boost success. In this fact sheet, each species’ explanation includes a summary of specifics.

A developing practice is to draw pollinators and give them food sources. The majority of gardeners envision hydrangeas as having huge, mophead-like blooms (see below), which are primarily sterile and lack the pollen needed to draw pollinators. However, certain hydrangea varieties feature fertile flowers that draw pollinators and produce pollen.

Both viable and infertile flowers are present in the hydrangea flower head. The gorgeous flowers really have showy sepals that support the petals, making them infertile blossoms. Less noticeable blooms are usually viable and have more observable floral components. Some hydrangea cultivars have fertile flowers that are very alluring to pollinators. The flower heads of hydrangeas often come in two varieties:

  • Mopheads beautiful, infertile blooms with a few less noticeable fertile flowers in the center of the flower head
  • Combination of fertile and sterile flowers known as lacecaps, with the infertile flowers typically clustered around the outside of the flower head (Dirr, 2004).

It will be crucial to choose hydrangeas with lacecap flower heads in order to draw pollinators to the area.

In spite of earlier beliefs that these hydrangeas would not attract pollinators, Ohio Master Gardener Volunteers discovered that some cultivars of oakleaf, smooth, and panicle hydrangeas were attracting a high level of some pollinators when conducting research and observations of cultivars for the Ohio Phenology Project. The project suggests that Oakleaf hydrangea blooms are regularly visited by pollinators, but more investigation and observation are required in this area to compile an exhaustive list of cultivars that are attractive to pollinators.

Pollinators are drawn to the Hydrangea paniculata ‘Great StarTM’ because of its fertile blossoms.

A few viable flowers of some Hydrangea arborescens species, such “Invincibelle Spirit,” are seductive to pollinators.

Site Selection and Planting

Since hydrangeas are wild plants, even those that are listed as needing full sun still require some shade. Depending on the condition of the soil and the availability of water, different amounts of shade will be needed. Many cultivars, including oakleaf and panicle varieties, are classified as preferring full sun to light shade. Due to its high water needs, bigleaf varieties require some shade.

When cultivated in partial shade with fewer than four hours of sunlight per day, Hydrangea paniculata ‘Vanilla StrawberryTM’ fades to dark pink and even purple.

The majority of cultivars grown in full sun in the garden will have leaves that droop during the hottest part of the day and flowers that fade to brown more quickly. Increased irrigation can mitigate these impacts of direct sunlight. On the other side, certain varieties will have smaller flowers and less foliage in intense shadow.

Smooth, oakleaf, creeping, and panicle kinds thrive in morning light with afternoon shade. If the correct soil and moisture conditions are maintained, many species may endure sunnier climates. More shade is needed for bigleaf hydrangeas, especially during the hotter parts of the day.

Make sure to place hydrangeas far from the roots or drip line of any nearby evergreen plants. Many evergreen plants compete with hydrangeas for water by having shallow root systems.

Loam soil, which has more sand and silt than clay, is preferred by hydrangeas. A soil that can retain water while being well-drained is necessary for growing hydrangeas. Soil that is loamy and well drained is ideal for growing hydrangeas. Heavy clay soils can be found throughout much of Ohio. Clay soils don’t make good growing environments for hydrangeas since they drain slowly and retain rainwater for extended periods of time. Before planting hydrangeas, gardeners should treat clay soils with organic matter to improve soil quality. Plant vigor will decrease, plants will become stressed and more prone to illnesses as well as winter damage if soil conditions are not corrected.

Hydrangeas require water, but they do not want their roots to be moist, therefore they also need good drainage. Planting hydrangeas in a location where water collects after a rainstorm is not advised. Raised beds ought to be taken into consideration in these locations to enhance the planting area’s drainage.

Tips for care

Contrary to what some would think, hydrangeas can get sick. Despite the low prevalence of aggressive diseases in the home garden, damage might nonetheless happen. Cercospora leaf spot (Cercospora hydrangea) and powdery mildew are the two diseases that affect hydrangeas the most frequently. Oakleaf hydrangeas and recently acquired plants that were cultivated in confined quarters appear to be the most susceptible to Cercospora leaf spot. Cercospora leaf spot and the majority of other common diseases will be less likely to infect plants the following growing season if fallen leaves are removed at the end of the season. Symptoms of powdery mildew resemble baby powder dusted on the plant’s leaves. Powdery mildew and other diseases can be reduced by trimming the plant to thin it out and by removing some foliage to increase air circulation.

Seasons of rain and high humidity create the perfect environment for disease growth. Most illnesses can be reduced by growing hydrangeas in the right place, with ideal soil conditions, and enough room for the plants (Penn State University Extension, 2017).

Species of Hydrangeas Grown in Ohio

Smooth Hydrangea Arborescens ‘Annabelle’ has a rounded flowerhead.

North America is the native home of Hydrangea arborescens. As it barely grows to a height of 3 feet per season, the plant is regarded as being fairly short. The size of flower heads, which are mounded, is determined by the species and trimming. The majority of the time, this species blooms in southern Ohio at the end of May and in northern Ohio at the beginning of June. This species’ cultivars can have flowers that are white, cream, pink, or lime green. If the plant has access to enough moisture, flowers will eventually become lime green later in the summer. Even if the majority of stems break and flower heads fall to the ground, faded blooms continue to bloom for portion of the winter. This plant blooms on fresh wood each year and is best suited for USDA hardiness zone 4. Smooth hydrangea are simple to split and propagate in the fall.

Every year, either in the very early spring or the very late fall, this plant can be pruned to a height of less than 4 inches. The cutting promotes more regular blooms and a more formal appearance the following spring. Larger blooms, with some flower heads spanning more than 12 inches across, will result from selectively cutting new growth in mid-spring to minimize the number of stems.

The plant will produce more blooms if the stems from the previous year are not clipped, but the blooms will be smaller and more irregular, giving the plant a more cottage-garden appearance.

North America is the plant’s natural habitat. The cultivar determines the range of sizes for this species. The plant may be tall and stout or short and wandering. Shorter cultivars keep below 3 feet, although the rambling style of the branches tends to spread 2 to 4 feet in each direction. The height of taller cultivars can reach 8 feet. Pyramidal flower heads with single-petal flowers that generally stand upright are common. The panicles can grow to a maximum length of 12 feet. At least two cultivars, “Snowflake” and “Gatsby’s Star,” exhibit what appear to be double flowers. These blooms droop under the weight of the blooms, creating a distinctive aspect in the landscape. As new sepals develop above the aging sepals, they will gradually turn pink and different colors of red. Plants in dappled or spotty shadow will have the longest blossom life with the most interest because full sun will fade the blooms to brown. In all of Ohio, this species starts to bloom in mid-June.

The most appealing feature of oakleaf hydrangeas is their leaves. The leaves resemble an oak tree leaf, as suggested by the popular name. While others have sharp tips, some have rounded tips. Some cultivars of this plant grow leaves that are 12 inches long and have gorgeous crimson and purple fall colors. This is a fantastic replacement plant for the ubiquitous burning bush, Euyonymus alatus, thanks to its fall color.

Oakleaf hydrangeas bloom on old wood, which means they produce flowers on growth from the previous year. The buds can withstand temperatures as low as zero degrees. Buds may be harmed in winters with lows of 10 degrees F, which could lead to a spring bloom that is only partially bloomed. All buds will die at temperatures below 20 degrees Fahrenheit, thus there won’t be any flowers the following growing season.

By layering, this species can be reproduced. To layer, in the spring, bend a lower branch to the ground, cover it with dirt, and then secure it with a brick. Keep the tip 6 to 8 inches above ground. In the late fall or the spring after, this new layer can be cut off for transplantation.

Depending on the cultivar and soil conditions, Hydrangea macrophylla (bigleaf) and Hydrangea serrata (mountain) have flowers that are either pink or blue in color. Although less robust than Hydrangea macrophylla, Hydrangea serrata is a little more hardy (Dirr, 2004). Gardeners are drawn to these two species because of their stunning blue and pink hues. These hydrangeas primarily have mophead flowers.

Due to its size, quantity of flowers, and capacity to dependably turn blue in the correct soil, the cultivar “Nikko Blue” has become an industry standard and is frequently offered in garden centers all across Ohio. Gardeners should be advised that this plant prefers aged wood and grows best in a protected environment or microclimate comparable to southern Ohio. Winter protection is necessary in Ohio’s colder regions in order to prevent erratic or nonexistent blooms. Below is an explanation of winter protection. This plant will grow larger than other macrophylla varieties and have lovely green foliage in years without blooms.

For most gardeners, the greatest options for bigleaf hydrangea success are the more recent cultivars, which bloom on both old and new wood. These plants must be protected by gardeners during the April frost, or the stressed plant will postpone or limit the season’s blossoming. Protection is still advised during the winter. Due to the hard site circumstances and poor soil conditions, most gardeners may not be successful with these plants.

Winter protection is necessary for cultivars that bloom on old wood in order to produce their best blooms the following season. For these plants, protecting three buds is sufficient to guarantee flowers the next year, so gardeners can cut back to just above the third bud and use winter protection techniques like piling with mulch, enclosing with leaves and compost, or other techniques. The two main obstacles to ensuring blooms are:

  • Once the fresh leaf buds start to develop in late March, remove the winter covering.
  • In April and the first few days of May, give protection from strong frosts.

Although winter protection might be effective, failing to take precautions against late-spring frosts will render the effort useless.

How to Troubleshoot a Plant That Has No Blooms: If a gardener notices that their plant has no blooms, it may be a variety that only blossoms on old wood, and the blooms may have been unintentionally cut off in the fall or spring. In the absence of cultivar identification and inconsistent annual flowering, new growth should be checked for buds during the current growing season. Gardeners who are unable to give winter protection should select a new cultivar that blooms on both old and new wood if the plant only produces flowers on old wood. Plant stress brought on by poor soil conditions, such as primarily clay soil with inadequate drainage, may also be the cause of the absence of flowers. For best results, the soil should be treated before growing this plant. This plant needs watering during dry times and whenever it is exposed to the sun’s heat. Due to the high nutrient requirements of bigleaf hydrangeas, a balanced fertilizer will guarantee healthy development and flowering throughout the growing season.

Mountain and bigleaf hydrangea blossoms appear blue or pink depending on the soil pH and related amount of accessible aluminum. Because aluminum is more easily available to plants in acidic soils with lower pH values, blue blooms result. Higher pH values (more alkaline soils) result in less readily available aluminum and pink blooms. For consistent blue in mineral soils, the soil pH should be between 5.5 and 6.5, and between 6.5 and 7.5 for consistent pink (Dirr, 2004). Gardeners should have their soil analyzed by a soil lab to obtain an accurate pH reading as well as the information and suggestions needed to apply the right quantity of lime or sulfur for the desired flower color.

Gardeners may need to wait a year before noticing a discernible transition from blue to pink flowers since raising soil pH takes longer than reducing pH. Because some soils may be heavy in phosphorus and maybe low in aluminum, some flowers may not turn blue in a year even when the pH is dropped. This is significant because aluminum phosphate becomes inaccessible to plants when phosphorus levels are high at low pH levels due of phosphorus’ reaction with aluminum. While a soil test will tell you how much phosphorus is present, an aluminum test normally costs extra but is necessary if you want blue blooms in the future. If a constant color is required, a soil test should be conducted every year.

Without a reliable soil test for the garden location, there is no definitive advice on how much sulfur or lime should be added to adjust the pH of the soil. Publications and websites that provide precise recipes are not appropriate for particular soil conditions. For these hydrangeas, recommendations based on a soil test are the only method to guarantee that the required color can be obtained. This kind of hydrangea can be reproduced by stacking, just like oakleaf hydrangeas.

Although it belongs to the hydrangea family, Hydrangea anomala resembles a plant from an entirely different family. Once this plant has established itself, lacecap blooms start to grow in abundance. Flowers on spp. glabra, “Crug Coral,” can range from white to cream and pink. This climbing vine uses holdfasts that resemble roots to cling to objects, yet it finally takes on the shape of a shrub (Dirr, 2004). Because of its adaptability, the plant can be raised as a shrub or directed to a trellis. The vines need robust support since their large, heavy branches are highly woody. Typically oval in shape, approximately an inch wide, pointed at the tip, and with finely serrated edges, the leaves are shiny green. For the first three years, the plant develops slowly; however, after it is established, it grows quickly. If cultivated outside, it blooms on old wood and is vulnerable to drying winds in the early spring. The maximum yield of blossoms and foliage will result by growing this vine in a protected location away from wind exposure. Typically, this is the building or home’s north side. The variegated cultivar “Firefly” has dark green leaf centers and cream to chartreuse-colored borders. Older stems have peeling, cinnamon-colored bark.

Grandma’s PG hydrangea is another name for the hydrangea paniculata. This species is consistently producing new cultivars. The majority of the flower heads have pyramidal shapes. The big, dense flower heads of “Limelight” are one type of flower head, whereas “Tardiva” has a mix of fertile and infertile flowers, and “Little Lamb” has flowers that don’t seem to open. This species’ flowers can be white, cream, lime green, pink, or even have reddish undertones in rare cases. There are both tall and short varieties; for instance, “Limelight” can grow to a height of at least 8 feet in the correct environment with loam soil. A spring growth spurt with bloom heads larger than 12 inches in diameter will come from pruning these large, established plants to 24 inches after each season. In order to achieve a reduced height, “Bobo” will stay below 4 feet and will produce an abundance of blossoms. There are compact varieties available that maintain a height of 2 to 4 feet, requiring less pruning. Since the larger varieties may be trained on one stem to resemble a tree, panicle hydrangeas are the only species that can be grown as a tree.

Some paniculata cultivars will retain their bloom heads even though many hydrangeas lose their fascinating flower heads in the late fall and early winter. As new growth appears in the spring, Hydrangea paniculata ‘Limelight’ retains its bloom heads for a long time. These can be unattractive in the garden, but they can be cut down at any time after the flowers have faded with pruning. Some cultivars, including “Great Star” and “Vanilla Strawberry,” have weaker flower attachments that will drop off in the early winter, giving the garden a cleaner appearance in the early spring without pruning.

Selection Chart for Ohio Hydrangeas

To help gardeners choose plants for their gardens, this chart provides a summary of the species. The observations used to make the notations were made across several growing seasons and were supported by written documentation. There is simply not enough space or knowledge of further cultivars to detail them accurately. Other cultivars that are not included or discussed will nevertheless flourish in Ohio. Every year, there are so many brand-new hydrangea varieties available that it would be impossible to cover all the options for gardening success in Ohio. To make the best choice for the garden, gardeners must continue to watch novel varieties and conduct some simple study.