When to prune forsythia for vibrant yellow blooms

Wondering when to prune forsythia? You're not alone: the resplendent yellow blooms of this flowering shrub can be spotted gracing countless homes around the UK – but it's important to know how to keep yours looking its sunshine-coloured best.

Just as you need to know when to cut buddleja back, the same is true of the forsythia: taking your pruning shears to it at the wrong time of year can actually cause it to lose a lot of its famous flowers.

If you stick to your forsythia's schedule, however, we promise it'll reward your efforts by adding plenty of colour to your garden come springtime. 

When to prune forsythia

Every gardener worth their salt knows when to plant bulbs for spring, but it's easy to forget that the forsythia is actually one of the brightest and best springtime flowers around.

'Forsythia is one of the first shrubs to bloom, often flowering before its leaves emerge,' says Christopher O'Donoghue, one of the co-directors at Gardens Revived.

Christopher O'Donoghue

A gardener with over a decade of experience under his belt, Christopher set up Gardens Revived with his brother, Andrew, in 2018  to create a thriving family business. Together, they have worked on residential gardens, listed buildings and gardens, flower shows and large estates with some exceeding 70 acres – many with historical significance.

'Providing a striking display when many other plants are still dormant, this hardy shrub adds a burst of warmth and signals the arrival of the new growing season,' he adds.

That being said, it's important to get to grips with your forsythia's growing schedule before you start cutting it back. 

Because, while it absolutely needs to be pruned if you don't want it to become an ungainly mess of bare roots and patchy flowers, pruning too early will almost always lead to a decline in flowers. Which, considering that those yellow blooms are this shrub's USP, would be a crime.

When to get to work

'You need to wait until just after the brilliant yellow blossoms have faded in early spring,' says Steven Bell, gardening enthusiast and the CEO of Paving Shopper.

Steven Bell

Steven Bell is the managing director of Paving Shopper, known for his expertise in gardening, landscaping and paving. He leads the company with a focus on quality and innovation, ensuring Paving Shopper remains a trusted source for diverse paving needs.'

Noting that this will 'typically fall in late April or early May,' Steven goes on to explain that 'pruning at this point in time allows the plant to recover by developing new growth that will set the all-important flower buds for the following season'.

'Get to work as soon as those flowers fade,' agrees Christopher, 'and avoid pruning too late in the season, as it will likely remove buds for the following year.'

What you will need

Now that you know when to prune forsythia, it's important to make sure you have the right tools for the job.

With that in mind, then, you'll want to have the following to hand:

• A good pair of pruning shears from Amazon: these will work a lot like hand scissors, allowing you to get to work on those smaller stems with ease.
• A small pruning saw from Amazon: this will be useful for those slightly larger branches.
• A pair of long-reach loppers from Amazon: a must for those hard-to-reach areas.
• A decent pair of gardening gloves: it's always a good idea to protect yourself from cuts and scratches.
• A bag for cuttings: be sure to chuck these in your compost bin or green waste when you're done!

'Remember to make sure you're only ever using sharp, clean pruning tools,' says Christopher. 

Take care, too, that you're only pruning an established plant: younger plants need time to develop naturally. Just remove any dead, damaged or badly positioned shoots come springtime and leave them be!

Step-by-step guide

As is so often the case with pruning, it's important to work with your forsythia rather than against it when you're cutting it back.

'You'll want to avoid any aggressive hacking or drastic reshaping that could send these early-blooming shrubs into shock,' says Steven.

'Instead, I favor more moderate, selective thinning that respects the plant's natural form.'

 Let's dive on in, shall we?

1. Cut your forsythia back

Once you know when to prune forsythia, 'you'll want to trim the oldest stems at ground level to encourage new growth from the base,' says Christopher. 

Removing about one-fifth of the stems at the base of the shrub will 'help maintain a healthy, vigorous plant'.

'Proper pruning cuts made just above healthy buds or stems also speed healing and lower disease susceptibility,' says Steven. 'Just try to resist the impulse to overprune, and let the plant itself guide you to determine which branches are best removed!'

2. Thin it down

When pruning your forsythia, it's important to 'remove a portion of the older wood to encourage air circulation and sunlight penetration,' says Christopher, noting that doing so will 'reduce the risk of disease'.

The aim here is to make sure the centre of the bush isn't too crowded, essentially, and that any weak growth is removed.

3. And don't forget to deadhead

Deadheading is one of the most oddly satisfying gardening tasks around, so you'll be pleased to know that it's a must for your forsythia.

'Remove any spent flowers to improve the plant's appearance and prevent the formation of seeds, directing energy back into the plant,' says Christopher.

FAQs

When can I cut back forsythia?

As forsythias bloom on the previous year's growth, the best time to prune forsythias is immediately after flowering.

'I advise against delaying forsythia pruning too late into spring or early summer, as this runs the risk of accidentally removing newly developed flower buds,' says Steven. 

'Cutting back immediately after flowering also has the benefit of avoiding interference with next year's spring display – and, personally, I've always found late April/early May to be the prime "Goldilocks" window for forsythia pruning year after year!'

Can you prune forsythia in June?

Forsythia should be pruned in mid-spring, immediately after flowering. The only time you might want to do this later is if you want to give it a new lease of life by hard pruning. 

'It’s best to carry this out during the dormant season, between autumn and early spring,' explain the experts at the Royal Horticultural Society (RHS).

However, if you do pursue this course, remember that your shrub won’t produce any flowers in the first spring after its hard prune.

Can forsythia be cut back hard?

Forsythia can be cut back hard in the autumn/winter. All you have to do is cut all stems down so they sit about 10-20cm from the ground, sprinkle a slow-release granular fertiliser (like Growmore from Homebase) around the base, and take care to give them a good mulching in the springtime.

A whole new set of branches should emerge come springtime.

Now that you know when to prune forsythia, you're well on your way to making your bee garden ideas a reality with these pollinator-friendly blooms.

'With proper care and attention, this hardy shrub will become one of the most cherished plants in your garden,' promises Christopher.