Hydrangeas not blooming? Here’s help

By Lynette L. Walther | Jul 26, 2019
Photo by: Lynette L. Walther A line of mixed hydrangeas, with a bigleaf in the foreground, shows the differences in their bloom forms.The big white blooms above it are ‘Incrediball’ smooth, or Annabelle, hydrangeas.

One of the most spectacular floral shows of every summer are the bigleaf hydrangeas. These hardy blooming shrubs almost never fail to amaze us with their puffy balls of blooms. I say almost, because sometimes, for some people, they refuse to bloom. And for those with that issue, we need to discover the cause.

Bigleaf hydrangeas, or macrophylla, are recognizable by their big green leaves and extravagant flowering heads of white, pink or sometimes blue blooms. After a winter like our last one, many area gardeners are reporting lots of dead stems and no flowers. The bloom detectives are on this case, and here are some suggestions to remedy this issue.

No. 1 — Location, location, location

Many bigleaf hydrangea varieties bloom on old wood; that means that stems formed this year will produce next year’s flowers. Winter die-back can damage or destroy stems. Consider relocating hydrangeas to sites where they get plenty of morning sun (at least three hours) and some protection from fierce winter winds. A building, a fence or even a windbreak of evergreens can make a positive difference.

No. 2 — Nitrogen

While many plants and lawns thrive on plenty of nitrogen, but when it comes to hydrangeas, even a little can be too much. So plants will produce plenty of leaves and forget about the flowers.

No. 3 — Strength

Establishing any new plants can be stressful for the plants themselves, and the same goes for your hydrangeas. They may appear to be tough as nails, but it takes healthy hydrangeas to produce flowers. A good, acid-based, granular fertilizer or rich compost can help grow strong plants. After the beginning of August, stop adding nutrients to allow the shrubs to transition into dormancy and not put out new growth.

No. 4 -- Irrigation

Hydrangeas prefer plenty of moisture, but require good drainage as well. Plants that sit in low areas that retain water will not thrive, because it can starve the roots of oxygen, eventually causing rot, or kill the plant. As with too much nitrogen, too much water can also result in all luxuriant foliage and no flowers. Plants may droop during the heat of the day, but wait until later to water — only if it remains limp.

No. 5 -- Pruning

To trim or not to trim? With differing pruning guidelines for various types of hydrangeas, it can get confusing. In the coming weeks, bigleaf hydrangeas will be setting buds for next year’s blooms. Many newer varieties will bloom on both old and new wood. Older varieties bloom on old wood. That means next year’s blooms begin and are formed on this year’s stems. Trimming back in the coming weeks or in the spring can remove next year’s buds and blooms — one of the most common causes for lack of flowers. If a stem appears dead, either now or next spring, check it first to make sure it is not dormant. Scratch the surface just a bit and if you see green, it is a viable stem. Do not cut.

Varieties of bigleaf hydrangeas that bloom on both old and new wood include: ‘Let’s Dance’ selections: “Big Easy” with deep pink blooms, “Blue Jangles” with blue flowers, “Diva” blue panicles, “Rave” with huge violet-pink blooms, ‘Rhythmic Blue” with reblooming blue blossoms, “Starlight” with pink to blue lacecap blooms, depending on soil conditions. “Cityline” group of bigleaf hydrangeas feature deep green foliage and a dense growth pattern and include: ‘Berlin’ with ivory-centered lavender blooms, ‘Mars’ with stunning white-rimmed pink flowers, ‘Paris’ with rich red blooms, ‘Rio’ with deep blue blooms, ‘Venice’ with pink to purple blooms, and ‘Vienna’ with huge pink to rich blue blooms. “Abracadabra” line of bigleaf hydrangeas have silky black stems and include: ‘Orb’ with pink mopheads, ‘Star’ with pink lacecaps, ‘Hearts’ with bi-color deep pink/white flower heads, and ‘Paraplu’ with double showy florets and leathery foliage.

An expansive group of flowering shrubs, hydrangeas are a good choice for area gardens. They include the bigleaf (H. macrophylla); panicle (H. paniculata); oakleaf (H. quercifolia); mountain (H. serrata); climbing (H. anomala); and smooth (H. aborescens). All together, hydrangeas offer something for everyone and every landscape.

My neighbor's garden is a stunning display of a variety of hydrangeas, accented with perennials. (Photo by: Lynette L. Walther)
When and what to trim is the conundrum when it comes to hydrangeas. Bigleaf, or macrophylla, hydrangeas can often suffer winter damage like this one in the foreground. (Photo by: Lynette L. Walther)
Comments (0)
If you wish to comment, please login.