Prune These 9 Flowering Shrubs in June Before They Set Next Year’s Buds and It’s Too Late

The heavy, sweet scent of spring is completely gone, and your garden paths are likely covered in a papery brown carpet of spent petals. And – let’s be honest – when June arrives and the weather finally starts to warm up, the last thing many of us gardeners want to do is drag out the loppers and start pruning shrubs.

So we put it off.

We look at those large, leafy plants and tell ourselves we’ll deal with them in autumn. Or winter. When there is less to do.

A very costly mistake indeed!

The moment many spring-flowering shrubs finish blooming, they start preparing for next year’s display. Fresh green shoots appear, growth surges, and hidden inside that new growth are the flower buds that will open next spring. You cannot see them yet, but they are already there.

I can hear you… “Surely a few months won’t matter?” you are thinking.

In fact, they matter a great deal. Wait until fall or winter to prune, and you may remove hundreds of flower buds without even realizing it. The shrub will survive, of course. But next spring’s display could be a shadow of what it should have been.

That is why June is such an important month. It gives us a narrow window to reduce size, remove aging wood, improve airflow, and encourage vigorous new growth before next year’s flower buds are fully set.

And there is another reward waiting for us as well. More flowers next spring means more nectar for bees, butterflies, and all those little winged visitors that help bring our gardens to life.

So grab your sharpest pruners and don’t delay. These are the 9 flowering plants worth pruning in June before next year’s buds are locked in place and the opportunity disappears…

1. Forsythia (Forsythia spp.)

You may look at that massive, sprawling shrub now that its brilliant, golden flowers have faded, and think you can trim it back into a neat ball whenever you have time; a common mistake! If you want those vibrant, radiant yellow bells to bless our Zone 6 gardens again next early spring, we need to act right now.

In fact, Forsythia blooms entirely on old wood! It starts setting its flower buds for next year shortly after the current blossoms drop. So, if you wait until autumn or winter to give it a haircut, you will be slicing right through next year’s magnificent display!

I can hear you… “How do I control this whopping monster?” you are thinking. Let’s be honest, it is very easy! For general maintenance, grab your bypass pruners and shorten those long, arching stems by up to one-third of their length. Snip just above a healthy, vigorous outward-facing bud or a pair of rich green leaves. This simple cut slows the sprawling growth and encourages the plant to branch beautifully!

And there is more… if your shrub is a dense, tangled thicket, it needs a rejuvenation prune. Take your loppers and saw out up to one-third of the oldest, thickest canes right down to the ground. This opens the center to fresh air and sunshine, ensuring the little winged visitors will have an absolute feast when it explodes with bright color next year. It is an invaluable shrub for an informal, fiery hedge!

2. Mock Orange (Philadelphus spp.)

The intoxicating, sweet citrus scent of our mock orange is finally fading on the summer breeze, and you might just want to leave this sprawling shrub alone to enjoy its lush, deep green leaves. But wait! These vigorous growers bloom strictly on old wood. If we delay and wait until winter to tidy them up, we are quite literally throwing away next spring’s magnificent, pure white blossoms. June is our perfect, narrow window to act in our Zone 6 gardens.

So, grab your sharp bypass pruners! For routine shaping, simply trace the spent flowering stems down and snip them back to a strong, healthy, outward-facing bud or a fresh leafy side shoot. This precise cut stops the plant from wasting precious energy on seed capsules, pushing all that vitality into creating stiff, vibrant stems for next year.

And if your mock orange has turned into a massive, tangled thicket—which they absolutely love to do!—we need to be braver. Take your loppers and saw out up to one-third of the thickest, oldest gray canes right down to the soil line. This instantly opens the dark, crowded center to warm sunshine and fresh air, inviting our little winged visitors to easily flutter through the arching branches while keeping the entire shrub flourishing from the base!

3. Chinese Wisteria (Wisteria sinensis)

I can hear you… “It is taking over my entire pergola!” you are thinking. And – let’s be honest – you are probably right! Wisteria is a magnificent, towering vine that blesses us with breathtaking, pendulous blooms, but its summer growth is absolutely massive! You may think letting it grow wild will give you more flowers; a common mistake! If we let those long, whippy green vines just keep sprawling, the plant puts all its energy into lush foliage instead of next year’s flower buds.

So, what is the secret? After the main flush of flowers fades, we need to take action! Grab your sharpest pruners and shorten this year’s long, green side shoots to about 12 to 18 inches (30 to 45 cm), leaving exactly five or six waxy leaves on each shoot. In fact, this precise summer haircut slows the plant’s vigorous leafy growth, and it directs more energy into forming magnificent flower buds rather than producing endless vines!

What is more, keeping this vigorous grower under control ensures your garden structures stay safe, and the little winged visitors will have an absolute feast of nectar waiting for them when those extraordinary silvery blue and purple blossoms burst open again next spring. It is an invaluable vine for sprawling over sturdy arbors or training against strong walls!

4. Lilacs (Syringa spp.)

I can hear you… “The whole yard still smells like perfume and now you want me cutting?” you’re thinking. Wait! June is the only window we get. Lilacs set next year’s bloom buds on wood that grows this summer. Wait until July, and every snip removes a flower cluster you’ll never smell.

So grab your secateurs the moment those trusses turn papery. Snip each deadhead back to the first strong pair of leaves, or to an outward-facing bud. This stops the plant from pouring energy into seed production — let’s be honest, you didn’t plant a lilac for ugly brown pods. That fuel goes into fresh stems instead, and those stems harden by August with tiny buds already waiting inside.

But there’s more! Look at the base. Lilacs sucker like mad, sending up thin shoots that steal light and turn your shrub into a thicket. Cut the weakest ones flat to the ground. Then find the oldest, grey-barked stems — the ones blooming less every year. Saw one or two right at soil level. About one-third of the oldest wood per year is the sweet spot. It opens the center, lets sunlight hit young wood, and forces the plant to regenerate.

How much total? Roughly twenty to thirty percent — deadheads, weak suckers, and one old trunk. Never more than a third in a single season; lilacs sulk if you overdo it. Water deeply after, mulch the root zone, and step back. When that perfume fills the air next spring, you’ll know exactly why you were ruthless.

5. Spring-Blooming Spirea (Spiraea thunbergii and Spiraea × vanhouttei)

You may look at those magnificent, arching branches and think they are perfectly fine left alone; a common mistake! These spring-blooming beauties just finished blessing our gardens with their extraordinary, cascading waterfalls of pure white flowers. But if you want to keep that exquisite bridal wreath shape looking elegant rather than messy, we need to pick up our tools right now!

Why so soon? Spring spireas bloom entirely on old wood. In fact, if you delay this summer haircut and prune them in autumn, you will be chopping away the very stems that hold next year’s delicate floral display!

So, let’s get to work! For a simple tidy-up, take your sharp pruners and follow the spent flowering stems down, snipping just above a strong, healthy pair of finely textured, deep green leaves. This encourages fresh, vibrant side shoots instead of awkward, bare twigs.

And there is more… if your shrub has become a massive, tangled thicket, it is time for a rejuvenation cut! Saw out up to one-third of the thickest, oldest stems directly down to the soil level. This prevents the center from becoming a barren nest of old wood, ensuring lush foliage and abundant blossoms all the way to the base for our little winged visitors to enjoy next spring!

6. Flowering Quince (Chaenomeles spp.)

Flowering quince is one of the first shrubs to burst into bloom each spring, often covering its bare branches with brilliant scarlet, orange, pink, or white flowers before the leaves even appear. What many gardeners don’t realize is that those spectacular blooms are produced on short, stubby spurs that develop on older branches. Prune at the wrong time, and you can remove a surprising number of next year’s flowers.

As soon as flowering finishes, shorten flowered side shoots by about one-third, cutting back to a healthy outward-facing bud. Then thin out a few of the oldest, most congested stems at ground level to let light and air into the center of the shrub. This encourages fresh growth without sacrificing the mature wood that carries the heaviest bloom display.

Don’t be too eager to remove every old branch. Unlike some flowering shrubs, flowering quince often blooms most heavily on established stems that are several years old. The goal is renewal, not a drastic haircut. A well-pruned plant should still retain its natural, slightly tangled framework while making room for vigorous young shoots.

And there is a bonus! Many varieties produce decorative, fragrant fruits in autumn that can be turned into jellies and preserves. A little careful pruning in June helps ensure both a dazzling spring display and a good crop of these old-fashioned garden treasures next year…

7. Rhododendrons (Rhododendron spp.)

You may look at those spent, sticky flower heads and think you should just let them fall off naturally; a common mistake! If you want an explosion of exquisite, vibrant blooms next spring, we must act exactly in June.

So, what is the secret? After the main flush of flowers fades, take your thumb and forefinger, or small bypass pruners, and carefully snap off the spent flower truss right at its base. But wait! You must leave the whorl of new, pale green side shoots forming directly below it completely untouched. In fact, this precise deadheading stops the plant from wasting precious energy on seed production, and it directs more energy into forming massive, gorgeous flower buds for next year!

And there is more… if your shrub is towering and sprawling over a pathway, we can control its size right now. Shorten those long, woody side branches by about 12 to 24 inches (30 to 60 cm), making sure to slice exactly 1/4 inch (6 mm) above a dormant bud or a lower whorl of dense leaves. This slows the plant’s vigorous outward spread and forces dense, brilliant growth where you actually want it!

8. Weigela (Weigela spp.)

Weigela is one of those shrubs that tells you exactly when it wants pruning—right after flowering. By June, the trumpet-shaped blooms may be fading, but the shrub is already preparing the shoots that will carry next spring’s flowers. Wait until fall or winter, and you’ll remove many of those future blooms before they ever get the chance to open.

Start by cutting the flowered stems back by about one-third, making your cuts just above a strong pair of leaves or a vigorous side shoot. Then take a close look at the oldest branches. If they are thick, woody, and producing only a few flowers at the tips, remove a couple of them right down to the base.

Here’s something many gardeners miss: the most spectacular flowering often comes from young, vigorous stems that are one or two years old. An aging weigela can become a mass of old wood with blooms concentrated on the outer shell. Regular thinning encourages fresh canes that produce larger flower clusters and much stronger growth.

Avoid shearing the shrub into a formal mound. Weigela’s graceful, arching branches are part of its charm, and selective pruning preserves that natural shape while setting the stage for an even more colorful display next year…

9. Viburnum (Viburnum spp.)

Those gorgeous spring flower clusters may be fading now, but don’t ignore your viburnum just yet! June is when many spring-flowering varieties begin preparing next year’s display, and a few well-placed cuts can make all the difference.

You may think this is the moment to grab the hedge trimmers and give the whole shrub a neat haircut. But wait! That is often the fastest way to turn a magnificent flowering shrub into a dense green blob with fewer blooms every year.

Instead, step back and look deep inside the plant. Can you spot those thick, aging gray stems hidden in the center? They are often the least productive branches on the shrub. Remove up to one-third of these old canes right down at ground level. It feels dramatic, I know… But this simple trick encourages vigorous young shoots that will become the flowering stars of future seasons.

And there is another benefit! Opening up the center allows sunlight and fresh air to reach every corner of the shrub. Many of us gardeners focus on what is happening at the tips of the branches, while the real magic starts down below, where strong new replacement stems are waiting to emerge.

Leave the younger arching branches alone, put the hedge trimmers away, and let the shrub keep its natural shape. Your reward will be a healthier, more vigorous viburnum and an even more spectacular display of blooms next spring…