Monty Don’s March Hydrangea Pruning Trick for More Blooms

Many hydrangeas look disappointingly sparse in summer – yet the cause is often simply incorrect pruning in spring.

Anyone seeing fewer flowers on the shrub each year will know the frustration: the hydrangea appears healthy and produces green growth, but the spectacular display of blooms never arrives. British TV gardener Monty Don relies on a straightforward March routine to tackle precisely this issue, using only a few cuts and a layer of mulch.

Why March determines hydrangea flowers

Hydrangeas have a reputation for being easy to grow: they cope with partial shade and will even forgive the occasional missed watering. Even so, a few careless actions in late winter can cost them almost their entire floral display.

In particular, traditional mophead hydrangeas (Hydrangea macrophylla), with their rounded flower heads, develop their flower buds on what is known as old wood. In other words, the shoots due to flower in summer formed their buds in the previous year. Throughout winter, these remain on the branches as small, plump-looking eyes.

Gardeners who have a thorough tidy-up in January or February and remove the dried flower heads often cut off those very buds. The shrub may then look neat, but it will produce only a handful of isolated blooms in summer.

The crucial point is not what is cut away, but when the cut is made and how close it is to the bud.

Monty Don has turned this into one simple rule: wait until winter has genuinely ended, then work methodically.

How Monty Don prunes hydrangeas for more flowers

Monty Don draws a clear distinction between pruning back and simply removing spent blooms, known as deadheading. Many amateur gardeners treat them as the same task, then wonder about the result.

Deadheading means removing only the faded flower head without harming the buds beneath it. According to Monty Don, this requires just one precise cut:

Each old flower should be cut directly above the highest healthy pair of buds. The dried cap is removed, while the supporting shoot remains.

These are the buds that will grow in spring and produce that year's flowers. By March, the worst frost has passed, while the buds are more visible and easier to identify.

Monty Don and Alan Titchmarsh's March checklist

The advice from Monty Don and fellow TV gardener Alan Titchmarsh forms an uncomplicated routine that can be completed on a mild morning:

• Wait until the final period of frost has passed and the buds are visibly swelling.
• Cut every dried flower head just above the highest healthy pair of buds.
• Remove dead, damaged or very thin shoots at their base.
• Leave vigorous green shoots in place, as these will carry the summer flowers.

The key point is that most stems should remain on mophead hydrangeas flowering on old wood. Monty Don leaves major reshaping until immediately after flowering in late summer. A harder cut then will not damage the buds for the following year.

The mulch trick: unremarkable but highly effective

Alongside careful pruning, Monty Don uses another frequently overlooked measure: mulching. For him, applying a generous mulch layer in winter or very early spring is as much a part of hydrangea care as using the secateurs.

His approach is simple: when shrubs resemble bare sticks in January, cover the root area with a generous blanket of organic material. Suitable options include:

• well-rotted garden compost,
• mushroom compost,
• bark mulch, preferably pine bark for slightly acidic soil.

Monty Don recommends at least five centimetres of mulch, ideally twice that depth – be generous rather than sparing.

Spread the layer around the plant without piling it directly against the stems. It keeps the root area warm, helps the soil retain moisture for longer and significantly moderates temperature fluctuations. This is a distinct benefit for hydrangeas, which are sensitive to dry conditions.

When to apply mulch to hydrangeas

The best time is on a frost-free yet cool day in January or early March. The soil should be:

• unfrozen,
• not completely soaked or waterlogged,
• largely free of weeds.

Before mulching, it is worth carrying out a quick check: clear away old plant material, pull out shallow-rooted weeds and expose the base of the shrubs. Only then should the compost be spread over the area.

Common mistakes that cost flowers

Many gardeners want to get the garden into order during winter, but make exactly the wrong choice for their hydrangeas. The main mistakes can be reduced to three points:

• Pruning too early: Cutting back hard in December or January removes the flower buds already formed by the plants.
• Too much mulch directly against the stem: