Monty Don’s March Trick for More Hydrangea Blooms

That modest change in timing and approach, combined with a deep layer of mulch, transformed bare-looking stems into shrubs carrying so many flowers that neighbours began asking what I had done.

Why so many hydrangeas underperform

Hydrangeas ought to be the effortless stars of a British summer garden. They cope with shade, moist ground and occasional neglect more readily than plenty of other shrubs. Even so, many gardeners find that their plants produce fewer flowers each year, despite having plenty of healthy, green foliage.

The cause is often two seemingly minor practices: pruning at the wrong time and allowing the soil around the shrub to remain bare and lacking nourishment.

Most gardeners aren’t failing to grow hydrangeas; they’re accidentally cutting off next summer’s flowers months before they appear.

For years, Monty Don has consistently made the same point: avoid cutting back too severely, do not prune too soon, and allow March to take on part of the job.

Why March is Monty Don’s key month for hydrangeas

Many traditional cottage-garden hydrangeas, particularly mopheads (Hydrangea macrophylla), produce flowers on what gardeners describe as old wood. In other words:

• The buds that will flower this summer developed on last year’s stems.
• These buds remain on the shrub throughout winter, frequently just beneath each faded flower.
• Cutting back hard in autumn or early winter removes many of these buds.

When dead flower heads are removed in November, hidden buds often disappear with them. Although the shrub remains alive, its summer flowering display is greatly reduced.

Monty Don’s alteration is small but effective: keep the spent blooms on the plant during the coldest part of winter, then deal with them in March, when winter conditions have become less severe.

The old flower heads act like tiny umbrellas, shielding the delicate buds beneath from the sharpest frosts and wind.

Across much of the UK, the harshest frosts have normally passed by March. As the buds start to swell, it is much clearer where cuts can be made without sacrificing the coming season’s flowers.

How Monty Don deadheads for more hydrangea blooms

Monty Don makes an important distinction between deadheading and pruning. Deadheading means removing old flowers, whereas pruning changes the shrub’s shape or reduces its size. For hydrangeas that flower on old wood, March should chiefly involve gentle deadheading with only minimal tidying.

The exact cut he recommends

Monty Don’s technique is straightforward enough to carry out while holding a mug of tea:

• Wait until hard frosts are no longer likely and the buds look clearly swollen.
• Find the dried bloom at the tip of each stem.
• Trace the stem downwards to the uppermost pair of plump, healthy buds.
• Cut cleanly immediately above this pair of buds.

This small change makes a considerable difference. It removes the faded cluster of petals and any tip damaged by frost, while preserving the crucial buds. Those buds can then open into new shoots that will bear this year’s flowers.

Think of the March cut as changing the hydrangea’s hairstyle, not chopping its head off.

Monty, along with fellow television gardener Alan Titchmarsh, recommends keeping spring treatment light for old-wood hydrangeas. Leave more substantial reshaping or height reduction until late summer, immediately after flowering, giving the plant enough time to form fresh buds before winter arrives again.

A quick March checklist for busy gardeners

For most people, the March tasks can be completed during one mild morning:

• Remove every faded flower just above the highest pair of robust buds.
• Take dead, damaged or particularly weak stems down to the base.
• Keep strong green stems intact, as these will support the flowers.
• Pause before making further cuts; in most cases, less is more.

By July and August, this produces a denser mound of flowers with much less work than an elaborate pruning routine.

Monty Don’s mulching trick that quietly powers the buds

Pruning is only one part of Monty’s method. The second element takes place when many gardeners have stopped thinking about their borders altogether: in mid-winter and the earliest weeks of spring.

He strongly supports applying generous winter mulch around shrubs, including roses and hydrangeas, with well-rotted organic matter.

A thick winter mulch is like a duvet for your hydrangea’s roots: warming, protective and quietly feeding the soil.

What he uses – and what many gardeners get wrong

Monty prefers options including garden compost, mushroom compost and bark chippings. Pine bark is especially useful because it provides a slight increase in acidity, something that many hydrangeas enjoy.

His advice is to apply these materials generously:

Material	Suggested depth	Key benefit
Garden compost	5–10cm	Improves soil structure and feeds slowly
Mushroom compost	5–10cm	Retains moisture and boosts nutrients
Pine bark chippings	5–10cm	Helps keep roots cool, adds gentle acidity

When and where the mulch is applied matters most. Spread it on a mild day in January or early March, while the soil is cold but neither frozen nor waterlogged. Remove weeds beforehand, and leave the plant’s base, or “collar”, uncovered.

Problems can arise if mulch is packed tightly around stems, if unrotted raw materials are used, or if deep mulching is paired with severe winter pruning. This can cause buds to rot, stems to suffer and flowering to decline.

Common hydrangea pruning mistakes to avoid

Gardeners often make the same handful of mistakes with hydrangeas that bloom on old wood. Preventing them can improve results in just one growing season.

• Cutting every stem back to ankle level in autumn to make the plant look tidy.
• Taking off every dead flower in December and removing its protective covering.
• Cutting back heavily each spring to control size rather than thinning only a small number of old stems.
• Failing to distinguish between old-wood and new-wood varieties, then treating both in the same way.

Panicle and smooth hydrangeas, including Hydrangea paniculata and Hydrangea arborescens, grow differently. They flower on new wood, meaning they can tolerate-and may even benefit from-a more forceful cut in spring. Many UK gardeners grow these alongside classic mopheads, apply a single rule to every plant and get inconsistent results.

Small changes that make a visible difference

Monty Don’s approach appeals to gardeners with limited time because it treats hydrangeas as easy-going shrubs, rather than demanding divas. All that is generally needed is sharp secateurs, a barrow of mulch and attention to the possibility of late frosts.

Leave the heads on over winter, snip lightly in March, and give the roots a thick, nourishing blanket: that’s the core of the method.

This routine also improves the shrub’s resilience. A substantial mulch layer enables soil to retain moisture in dry periods, helping to limit wilting and brown flower edges. It protects the roots against sudden temperature changes that may harm developing buds. Over several seasons, the ground beneath the plant becomes richer and easier to cultivate, allowing the hydrangea’s roots to spread and support greater growth.

Extra tips for stronger colour and healthier shrubs

After establishing the March routine, a few additional adjustments can improve the flowering display further:

• Give plants a thorough soak during dry spells instead of watering lightly and frequently.
• Apply a slow-release shrub fertiliser in spring, but do not overuse nitrogen, which encourages foliage instead of blooms.
• Check the soil pH if you want blue or purple flowers; slightly acidic soil helps these colours remain strong.
• In exposed positions, cover plants with fleece if a sharp late frost is expected after the buds have opened.

Gardeners concerned about making a mistake can try the method on one shrub only. Keep another hydrangea on the previous routine as a discreet comparison. By August, differences in both the number and size of blooms will usually be obvious.

Hydrangeas may react gradually at first, but they can then reward you remarkably generously. Once Monty Don’s March technique is established-the careful deadheading and deep winter mulch-many gardeners find that their shrubs finally deliver what they promise: large, reliable plants generously covered with flowers year after year.