5 Reasons Why Hydrangeas Aren’t Flowering

Reasons why hydrangeas won’t flower

Hydrangeas are one of the most popular plants and are usually chosen for one reason; their blooms.

A healthy and well looked after hydrangea should produce an abundance of colourful flowers each year. Hydrangea blooms are often large, with deep colour, plentiful and last for a long time; they resist pests and are strong enough to cope with strong winds and rain.

Once established, a hydrangea should bloom every year, and if it doesn’t, you’ll need to change something.

Below you’ll find DIY Gardening’s 5 reasons why hydrangeas don’t flower which is part of our ultimate guide to growing hydrangeas.

1) Pruning

This is the most common reason why some hydrangeas don’t flower or only produce very small or weak flowers; incorrect pruning.

Different hydrangeas will have different pruning requirements, and some of these plants only flower on old wood, meaning if you prune off these old stems below a certain point, the plant won’t produce any flowers that year.

To confuse matters, some hydrangeas perform better after being pruned back to a framework of thicker stems or even close to ground level.

Below is a quick guide to pruning hydrangeas so they flower each year but if you’re in doubt or struggling to identify your hydrangea, just leave it be and don’t prune it all.

Once you’ve identified which hydrangea you have (watch this video for help), use this cheat sheet:

When to Prune:
Macrophylla (Mopheads & Lacecaps)
Two methods: In spring after frosts or immediately after blooms fade in summer, before next years buds have been set.
Oakleaf hydrangea
Two possible methods: In spring after frosts or immediately after blooms fade in summer, before next years buds have been set.
Paniculata hydrangea
Early spring.
Arborescens hydrangea
Early spring.
Climbing hydrangea
Late summer after blooms fade.
Flowers on:
Macrophylla (Mopheads & Lacecaps)
Old wood
Oakleaf hydrangea
Old wood
Paniculata hydrangea
New wood
Arborescens hydrangea
New wood
Climbing hydrangea
Old wood
Method:
Macrophylla (Mopheads & Lacecaps)
Doesn't require yearly pruning but you can prune off up to 20% of stems just above the crown in spring as this encourages new stems from the base, these will flower in the second year. Leave old blooms on over winter for frost protection and cut them off at the nearest set of buds after the last spring frosts but be aware that the deeper you prune a stem, the more buds you'll remove and the fewer flowers that will appear. Alternatively, prune in summer after the blooms fade and before the plant sets buds for next year.
Oakleaf hydrangea
Often requires less pruning. Cut off old blooms to nearest set of healthy buds. Remove up to 20% of old stems just above ground level to encourage new growth if required.
Paniculata hydrangea
Either cut back leaving 2-3 sets of buds on the previous year's growth or prune entire shrub back close to the framework (the thickest stems), leaving some buds on the stems. Ideally, remove about 30-50% of the plant and all skinny or weak stems, leaving a framework of thicker stems.
Arborescens hydrangea
Prune hard, 25cm from the ground to promote fewer but larger blooms or prune lightly to a framework 50cm from the ground to encourage more but smaller blooms.
Climbing hydrangea
Prune in summer after blooms have faded and before new buds form. Cut out overly long and wayward stems to desired length or to nearest large stem/branch.
Warnings:
Macrophylla (Mopheads & Lacecaps)
If you prune a stem by more than half, it's unlikely to produce blooms for the season but will in the second year. Or it may produce small blooms which are smoothered by leaves on longer, newer stems. Alternatively, prune after the blooms fade in summer and before the plant has set buds for next year. Be aware that in some climates, the old faded blooms offer winter protection from frost, hence why some gardeners leave them on over winter. If you cut off buds, or they are damaged by frost, then it won't bloom in the coming season.
Oakleaf hydrangea
As above.
Paniculata hydrangea
Can cope with more aggressive pruning. If pruned lightly, panicles will be more numerous but noticably smaller.
Arborescens hydrangea
Can cope with more aggresive pruning and is more forgiving.
Climbing hydrangea
To control a large wayward climber, consider twice yearly pruning to gradually bring it under control, leaving at least some buds for blooms.

Photos Showing Hydrangea Flowers on Old Wood

Hydrangea macrophylla is the plant with which gardeners have the most problems, as it’s less likely to bloom if pruned too hard.

The photos below show blooms appearing on old wood that grew last year.

New growth can also be seen in the photo, but this won’t produce flowers this year.

Note that macrophylla sets buds in autumn, and if you prune these off in the spring, it won’t flower that year.

Hydrangea flowering on old wood

Photo showing hydrangea macrophylla flowers growing from old wood near the tip of the old stem.

New stem growth on hydrangea

New growth from a stem that was pruned close to the ground in the spring. Note the lack of blooms.

2) Frost Damage

Frost can affect any hydrangea plant, but those that flower on new wood are less susceptible as any frost-damaged stems can be pruned off, and the hydrangea will still flower on new growth.

Hydrangeas that flower on old growth are a different matter. If the frost is severe and the buds are killed off, the plant won’t flower at all or may produce fewer flowers.

Frosts that occur in late spring are the most damaging as the buds will be growing. If you experience a mild winter followed by severe spring frosts, there’s a good chance your hydrangeas will experience some frost damage.

Here are our tips:

  • Keep hydrangeas (esp those in pots) watered through the winter, they still need moisture, and a weak plant is less likely to recover well from frost damage.
  • Consider using frost fleeces or other types of protection.
  • Relocate pot hydrangeas during cold frosty spells, especially if the winter was previously mild and the buds are growing.
  • Consider relocating a ground hydrangea to a less exposed location.
  • If you live in a frost-prone area, consider hydrangeas that bloom on new wood as they’re less likely to suffer frost related problems with flowering.

Frost Fleeces and Protection Jackets

There are dozens of frost protection products on the market, with fleeces and jackets being the most popular.

Jackets are great for plants that don’t grow much, while fleece wraps are better for larger plants.

Depending on where you live, you may not need to use these products all winter, only when frost is imminent.

3) Too Much Nitrogen

Some popular fertiliser products (such as Miricle Gro All Purpose) contain high doses of nitrogen, which promotes leaf and stem growth but often at the expense of flowers.

The Garden Myths website sums up these products perfectly:

“Too much fertilizer, particularly high nitrogen fertilizer, can result in beautiful leaves but few, if any, flowers.”

The best fertiliser for hydrangeas is one that’s balanced or has higher potassium.

Here are the ratios for two of the most popular hydrangea fertiliser products:

Westland Hydrangea Liquid Feed: 4-2-7 NPK.

Vitax Hydrangea Feed: 8-4-12 NPK.

(NPK means Nitrogen, Phosphorus, potassium, in that order)

Compare these ratios to the Miricle Gro All Purpose: 24-8-16 NPK.

In a nutshell: Avoid fertilisers with high concentrations of nitrogen. Instead, use a balanced feed or a dedicated product that will most likely have a slightly higher potassium level.

Recommended Hydrangea Feed

This product has the best ratio of nitrogen, phosphorous and potassium and is designed specifically for hydrangeas:

Vitax hydrangea feed

4) Too Much Sun/Shade

Go to any blog post or webpage about hydrangeas, and you’ll likely see a warning about sunlight.

I’ve even seen a few that claim hydrangeas should never be placed in direct sunlight!

The truth is that hydrangeas can cope with plenty of direct, midday sunlight, provided the soil isn’t allowed to dry out fully. 

Hydrangeas love moist soil and can struggle if grown in bone dry ground conditions, but only if they’re watered adequately. For those of us that live busy lives, this is always practical, so it’s easier to locate a hydrangea in dappled or partial sunlight where the soil stays moist for longer.

Unfortunately, hydrangeas do require some sunlight, and one placed in a very shaded spot is unlikely to produce many blooms, or the blooms will be small and weak.

The ideal spot for any hydrangea is:

  • A spot with plenty of morning sun.
  • An area with protection from searing midday sun if you’re unable to water the plant frequently.
  • Somewhere that provides dappled sunlight.
  • A pot that is large enough, so the soil doesn’t dry out every day.

If your hydrangea isn’t producing many blooms and isn’t in an ideal location, consider moving it.

5) Young and Recently Relocated Plants

Recently purchased hydrangeas may take a year or two to get going, so when looking around the local garden centre, try to find one that already has at least one flower.

Most hydrangeas grown from cuttings won’t flower in the first year but may do in the second year.

Also, established hydrangeas do suffer from transplant shock, so don’t be surprised if your plant doesn’t flower for a year after being relocated. The hydrangea is spending energy on root development and top growth at the expense of flowers and will likely recover the following year.

Other Reasons Hydrangeas Don’t Flower

Other reasons hydrangeas don’t flower:

Deers eating the buds – more common in the United States than in the UK, but deers can eat the young buds. This damage is exactly the same as improper pruning – the buds are destroyed before they have a chance to bloom.

Beetles can eat the young flowers and buds, but the beetle numbers would have to be high to affect an entire hydrangea plant.

Lack of water – as their name suggests, hydrangeas require more moisture than most shrubs, and a consistently underwatered hydrangea won’t bloom or will produce small, sickly flowers.

The Most Reliable Flowering Hydrangea

Hydrangeas are fairly easy shrubs to grow, but frost damage can be a persistent problem in some areas.

The hardiest hydrangea is the paniculata, and we recommend this to anyone who has consistently struggled to get other hydrangeas to bloom.

The paniculata is known as a reliable bloomer as it tolerates extremes much better than any other hydrangea:

  • Flowers on new growth so is less susceptible to frost damage.
  • Winter hardy to US zone 3.
  • Very forgiving of pruning mishaps and even prefers hard pruning.
  • Performs well in very shaded areas that many other hydrangeas struggle in.

Savvy Gardening has more information about the ever-reliable hydrangea paniculata.

White hydrangea paniculata flowering

Hydrangea Paniculata – winter hardy and a reliable bloomer

Recap

The most common reason for hydrangeas to stop flowering is incorrect pruning. This primarily affects macrophylla as other hydrangeas are more forgiving – if in doubt, don’t prune at all for a year to see what happens.

Frost damage can affect all hydrangeas but again affects those that flower on old wood more. Late spring frosts are the most damaging as new buds grow and are more susceptible to cold weather at this time of year.

Too much nitrogen, too little water and sunlight issues also prevent hydrangeas from flowering at their full potential.

Hydrangeas are beautiful plants and a mainstay of our garden, and we hope you found our guide to hydrangea flowering issues insightful.

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Free hydrangea photos
The ultimate guide to growing hydrangeas
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This hydrangea help guide was published by DIY Gardening

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