When to cut back lilies – and which parts to avoid trimming if you want them to bloom again next year

Figuring out when to cut back lilies isn't easy – and getting it wrong could mean the difference between successful flowers and cop-outs next year.

Learning how to deadhead lilies is one thing, but if you're keen to cut your plants back to encourage them to flower again next year, timing is everything. When it comes to lilies, though, 'cutting back' isn't what it sounds like – and you'll need to leave certain parts of the plant alone.

I asked the experts when we should be cutting back our lilies to make sure we aren't doing our plants more harm than good...

What you'll need

• A pair of secateurs, like the Darlac Compact Plus Pruner
• Or, some garden snips, like the Niwaki Garden Snips from Amazon (which I love!)
• A garden trug to collect plant material, like the Heritage Garden Trug from B&Q

If you're wondering what to do with lilies after flowering, you'll want to add cutting back to your list – but not for the whole plant at once.

'Lilies don’t need to be cut back until the flower petals have browned and started falling off, which typically will happen in August or September,' says Liam Cleary, garden retail director at Old Railway Line Garden Centre.

It's all about redirecting the plant's energy once it's finished blooming. 'When the flower has died, it starts putting energy into seed production, but this can impact the number of flowers you get the following year,' explains Liam.

It's crucial that you aren't targeting the wrong parts of the plant, though – and you'll need to leave the foliage well alone.

'You only want to remove the flower at this point, as the foliage is needed for energy storage that also helps produce more flowers next year,' says Liam.

Even if they look unsightly, it's important that you steer clear of the leaves while they're still green.

'Like other bulbs, after your lilies have finished flowering, the leaves will continue to feed the bulb, ensuring good flowering the following year – so don’t be tempted to cut them down too soon,' says Annelise Brilli, Thompson & Morgan's horticultural expert.

'Wait until both stems and leaves have gone yellow or brown, when the bulbs will be dormant. Then, you are safe to cut them back to a couple of inches above ground level.'

Removing spent blooms after the flowering period is one of the most important steps in learning how to grow lilies, though, especially if you want them to burst into flower again next year.

'For spent flowers, snip them just above a pair of leaves with sharp secateurs,' says Liam. 'For flowers that didn’t bloom on species like Asiatic or Oriental lilies, you may be able to quickly break the bud off with your hands.'

So, now we know when to cut back lilies: you're safe to cut away the spent blooms after they've finished flowering, but wait until the foliage has died right back before touching the leaves.