Monty Don’s March Hydrangea Trick for More Blooms

British television gardener Monty Don relies on a tiny but vital March routine that can determine whether hydrangeas produce a sparse or abundant summer display. Rather than expensive fertiliser or unusual varieties, it comes down to precise timing and a highly selective cut, combined with a straightforward winter mulching technique.

Why March determines hydrangea blooms

Hydrangeas are among the most popular flowering shrubs in UK gardens. Catalogue photographs show enormous clusters of flowers, yet plants in borders often produce only a few heads amid plenty of bare green growth. One major cause is pruning at the wrong time.

The familiar mophead and lacecap hydrangeas (Hydrangea macrophylla) are particularly affected. They form their flower buds in the previous year, on what is known as old wood. Cutting those shoots back hard removes precisely the growth points that should produce summer flowers.

“The most important point: many hydrangeas flower on the previous year’s growth. Pruning at the wrong time directly removes the coming display.”

March marks a delicate transition. Buds begin to swell and the plant emerges from winter dormancy, but night frosts may still occur. According to Monty Don, this stage determines whether shrubs will later be covered in large flower clusters or simply produce leafy growth.

Deadheading rather than cutting back: Monty Don’s light spring prune

A key issue is the confusion between two different jobs. For many gardeners, cutting is simply cutting, but professionals distinguish between removing faded flower heads and pruning back the plant properly.

• Deadheading: removing old flower heads only while leaving the shoots intact.
• Pruning back: shortening or fully removing stems to control shape and size.

Many people reach for the secateurs in winter and cut their hydrangeas back tidily. The result is that buds formed in the wood since the previous summer end up in the garden-waste bin. Monty Don therefore recommends a much gentler approach, carried out specifically in March.

Monty Don’s March hydrangea trick, step by step

Monty Don describes a precise, almost minimal approach to pruning:

• Choose the timing: late March is ideal, once the hardest frosts have passed and the buds are visibly swelling.
• Inspect the plant: look for the old, dried flower clusters on every shoot.
• Locate the cutting point: immediately beneath the brown flower head, there are usually one or two pairs of healthy, plump buds.
• Make the cut: place the secateurs just above the highest strong pair of buds, removing only the spent flower head and the poorest few centimetres at the tip.
• Remove dead wood only: cut out entirely brown, hollow or dead shoots close to ground level so that light and air can reach the centre of the shrub.

The essential point is that most of each shoot remains in place. The buds beneath the cut will then grow strongly and carry the much-wanted large flower heads in summer.

“A single cut a few millimetres above the right pair of buds can make the difference between two flowers and an entire shrub full of colourful blooms.”

What to consider for different hydrangea types

Not every hydrangea responds to pruning in the same way. Anyone growing several varieties should be able to tell them apart:

Type	Flowers on	Recommended pruning approach
Mophead / lacecap hydrangea (Hydrangea macrophylla)	old wood	In March, remove only old flower heads just above the first pair of buds; do not prune hard.
Panicle hydrangea (Hydrangea paniculata)	new wood	Can be cut back more firmly in late winter or early spring, as flowers form on new growth.
Smooth hydrangea (Hydrangea arborescens)	new wood	A stronger cut is also possible, often leaving only a few buds above ground level.

Monty Don’s “light prune” applies mainly to traditional garden hydrangeas that flower before June. One rule of thumb he has published is this: if a plant flowers before June, it is generally best not to cut it back hard in winter. This is exactly where most mistakes are made in home gardens.

The overlooked companion: Monty Don’s winter mulching ritual

Alongside the careful March cut, Monty Don uses a second, very down-to-earth measure: a thick layer of organic mulch in winter. It may not look dramatic, but over time it works like a wellbeing treatment for the roots.

How Monty Don mulches his borders

In January, when there seems to be little to do in the garden, he spreads a generous layer of mulch around his perennials and shrubs. His recommendations can easily be applied in UK gardens:

• Material: well-rotted compost, mushroom compost, chipped bark, leaf mould, or a mixture of whatever is available in your own garden.
• Depth: around 5 cm at a minimum, though 10 cm is better. His principle is that a thick layer over half the area is more effective than a paper-thin layer across the entire plot.
• Distance: do not pile mulch directly against the trunk or plant base; leave a small clear collar to prevent rot.

This layer protects sensitive roots from sharp temperature changes, keeps the soil moist for longer and feeds soil organisms. For hydrangeas, that means a strong start with vigorous shoots in spring, making it the ideal partner for targeted pruning in March.

“Stable roots, calm soil, targeted pruning – this combination creates the foundation for noticeably larger and more numerous hydrangea flowers.”

Practical guidance for everyday home gardening

Anyone wishing to try Monty Don’s method in their own garden can begin with just one shrub. These points are useful in practice:

• Never prune during a hard frost: mild, dry days in March or early April are preferable, as cuts heal more quickly.
• Use sharp, clean secateurs: crushed shoots weaken the plant and provide an entry point for fungal disease.
• Look closely first: the crucial buds are often inconspicuous and sit directly beneath the dried flower head.
• Less is better than more: when in doubt, leave a shoot in place and watch how the plant responds.

Many gardeners report noticeably more flowers even in the first year after taking a more cautious approach. The plants do not always look dramatically different, but the number of buds rises perceptibly.

Risks, exceptions and useful additions

There are, of course, exceptions. Old, severely neglected hydrangeas that have produced few flowers for years may sometimes benefit from more radical pruning. However, this often means accepting a full year with fewer blooms while new flowering shoots develop.

Late frosts can also be troublesome. In exposed locations, gardeners sometimes deliberately leave dried flower heads in place for longer, as they shelter the buds like small umbrellas. Pruning is then delayed until late March or early April, when the risk has reduced.

For a more complete care routine, pay attention to two further points: adequate watering during dry periods and soil that is slightly acidic to neutral. Mophead hydrangeas especially appreciate low-lime water, so in some areas it is worthwhile collecting rainwater for plants in pots and containers.

Ultimately, the difference between an “quite okay” hydrangea shrub and a truly impressive one does not lie in specialist fertilisers or exotic varieties, but in small routines: gentle pruning in March, a healthy amount of mulch in winter, and close attention to buds and shoots. Anyone who adopts these habits can come remarkably close to achieving the picture-perfect hydrangea in their own garden.