Monty Don’s March Hydrangea Pruning and Mulch Trick for More Flowers

Many gardeners feed and water their hydrangeas faithfully, yet still wonder why the displays become less lavish each year. British television gardener Monty Don relies on a small March routine: highly selective pruning followed by a layer of mulch. It may sound unremarkable, but it changes how the shrub copes with frost, moisture and buds – and therefore how many flowers it produces.

Why March determines hydrangea flowering

Hydrangeas have a reputation for being hardy, low-maintenance plants, and they will grow even in partly shaded spots where roses have long since failed. Even so, many varieties react very badly when they are pruned at the wrong time.

This is especially true of traditional bigleaf hydrangeas (Hydrangea macrophylla), often called mophead hydrangeas, which flower on what is known as “old wood”. In other words, their buds for the following summer have already formed on the stems during the previous year and remain there throughout winter.

Gardeners who have a winter tidy-up and cut away every old flowerhead generously often remove the buds for the entire following season at the same time. The shrub may look neat and orderly in May, but appear surprisingly sparse by July.

“The key point with hydrangeas is rarely how much you cut – but when and where you put the secateurs.”

Monty Don, along with fellow British gardener Alan Titchmarsh, therefore advocates a change of mindset: accept the plant's winter dormancy, leave faded flowerheads in place, and only reach for the secateurs in March, once the worst frosts have passed and the buds are clearly visible.

Monty Don’s pruning trick: gentle deadheading rather than hard pruning

Many gardeners treat pruning back and removing spent blooms as if they were the same task. With hydrangeas, recognising the difference can determine whether you get a mass of flowers or simply a ball of green foliage.

How to prune hydrangeas in March, step by step

For mophead hydrangeas, Monty Don recommends only a light touch in March. This is not a drastic overhaul, but careful work just above the correct pairs of buds:

• Wait for a frost-free spell in late February or March, ideally when the buds are visibly swelling.
• Inspect each dried flowerhead separately and cut it off immediately above the highest healthy pair of buds.
• Remove blackened, dead or dry stems completely at the base.
• Leave strong green stems untouched, as these will carry the season’s flowers.

This approach, known as deadheading, takes away only the dried flowerhead and often the frost-damaged tip of the stem. The two buds below remain intact and can reliably grow away in spring.

“When pruning hydrangeas in March, the secateurs should protect the buds rather than ‘shape’ the plant – Monty Don reserves shaping work for after flowering.”

When more substantial pruning is suitable

Not all hydrangeas behave in the same way. Some types, including many panicle hydrangeas and smooth hydrangeas (Hydrangea paniculata and Hydrangea arborescens), flower on “new wood”, meaning growth produced during the current year. They can cope better with a harder cut in late winter or very early spring.

Hydrangea type	Flowers on	Recommended pruning	Timing
Mophead hydrangea (macrophylla, mophead)	old wood	Remove only old flowers just above buds; thin out older stems after flowering	March (lightly); more heavily immediately after flowering
Panicle hydrangea (paniculata)	current-year wood	Cut back firmly while retaining the framework	Late winter to very early spring
Smooth hydrangea (arborescens)	current-year wood	Prune back boldly, usually cutting down hard	Late winter to March

The straightforward rule for amateur gardeners is this: if you do not know which hydrangea you have, take the cautious route and treat it like a mophead hydrangea. In the first year, it is better to prune a little less and see how it flowers.

The mulch that works quietly in the soil

As well as pruning, Monty Don consistently uses mulch around hydrangeas, roses and other shrubs during winter. It may not look like much from above, but this measure has a major influence on how evenly a plant grows and how reliably its buds survive the winter.

Monty Don’s advice on mulching

He uses well-rotted organic matter. Suitable options include:

• mature homemade garden compost
• mushroom compost
• bark mulch or chipped bark, preferably slightly acidic material such as pine bark

The layer should be about 5–10 cm deep. Apply it on mild days in January or in very early spring, provided the soil is neither frozen nor completely waterlogged.

“Monty Don prefers a thick layer of mulch every other year to a thin covering every year – the effect on soil life and the root environment is much stronger this way.”

One point matters: spread the mulch as a ring around the plant rather than against its stems. Keep the area around the crown clear, so the base does not rot and mould problems do not develop.

Why mulch encourages more hydrangea flowers

A mulching layer shields the soil from sudden shifts in temperature. This lessens frost damage around the roots, while the faded flowerheads provide some additional protection for the buds above ground. At the same time, mulch keeps moisture in the soil for longer and gradually feeds soil organisms with nutrients over several months.

Hydrangeas in particular are highly sensitive to fluctuating moisture levels. Prolonged drought or standing water causes stress, and the plant is then more likely to focus on survival than on producing plenty of flowers. Mulch acts as a buffer here.

Mistakes many amateur gardeners repeat every year

In typical suburban gardens across Germany and Austria, the same patterns repeatedly cost hydrangeas their flowers:

• Drastic pruning in December: In the urge to tidy up, all old flowerheads and stems are cut back hard. The summer’s buds go into the green-waste bin.
• Fresh bark mulch placed against the stems: Unrotted material temporarily draws nitrogen from the soil and may cause the plant base to rot.
• Waterlogging in containers: Attractive patio pots without drainage holes may look good, but they can cause hydrangea roots to rot in large numbers.
• Too much general fertiliser in spring: The plant may produce rich green growth, but set fewer buds because it is pushed too far into “growth mode”.

Correcting just one of these issues and trying Monty Don’s March pruning method often produces a noticeable difference in the number and size of flowerheads as early as the first summer.

Practical routine: the 30-minute spring check

For many amateur gardeners, the diary is already full. A simple routine makes this ritual easier to maintain. Here is an example of a quick hydrangea check on a mild March morning:

• Check the forecast: is a frost-free week expected? If so, get started.
• Remove weeds roughly around each hydrangea and lightly loosen the soil.
• Take each stem carrying a faded flowerhead, find a healthy pair of buds and cut just above it.
• Remove dead stems, stems growing inwards and any that cross one another.
• If you have not already done so, spread a 5–10 cm layer of mulch around the shrub without covering its base.

Nothing more needs to be done at that point. Watering can wait until later, drier periods, while organic slow-release fertiliser can be applied in April or May.

What terms such as “old wood” and “bud protection” really mean

Many gardening guides use technical expressions that sound as though they come straight from a textbook. There is nothing mysterious about “old wood”: it simply refers to stems that have already completed a growing season and become woody. On many hydrangeas, these are exactly the stems carrying the flower buds for the following year.

In this context, “bud protection” has two aspects. First, faded flowerheads offer physical shelter, hanging over the buds like small umbrellas. Second, sensible pruning and stable soil conditions protect buds from freezing, drying out or being weakened by a lack of nutrients.

Why patience pays off with hydrangeas

Anyone who has pruned hydrangeas heavily at the wrong time is often left with an almost flowerless summer. That can be frustrating and may quickly lead to rushed remedies, such as applying more fertiliser or cutting back again. A more useful approach is to think in terms of two to three years.

In the first year, use a gentle March prune that focuses on preserving buds, along with a good layer of mulch. In the second year, you can be more targeted: after flowering, remove one or two of the oldest, tired stems close to ground level so young, vigorous replacement shoots can emerge from below. This gradually rejuvenates the shrub without losing an entire flowering season.

Once you establish this combination of patience, a small March task and undisturbed soil for your hydrangeas, you may have a real light-bulb moment. The shrub can look almost unremarkable in spring, then suddenly burst into flowerheads at midsummer as though someone had secretly buried an XXL fertiliser dose beneath it. In reality, it is simply an easy, well-timed technique that surprisingly many gardeners overlook.