When to plant agapanthus - the exact time you should be planting bare-root plants and seeds for guaranteed summer blooms

Spotted your neighbour’s blooming agapanthus on your morning walk? Entranced by the many agapanthus plants on offer at the garden centre? We don’t blame you. But if you want to add this beautiful plant to your garden, you need to know when to plant agapanthus.

Yes, if you want to add height, drama, and colour to your garden borders, you can’t go wrong with agapanthus. Their globular flowerheads are made up of hundreds of smaller white or blue flowers that will brighten up any garden idea and bloom throughout the summer.

Because of this, you’ll generally find agapanthus plants in garden centres and online during the warmer months. And if you buy these ready-to-plant options, you can grab your gardening gloves and plant them straight away. But if you buy bare-root plants or seeds, when you plant agapanthus is determined by which one you choose.

When to plant bare-root agapanthus

If you want to grow agapanthus at home, you can buy bare-root agapanthus. But it’s important to know when to plant agapanthus roots as planting at the wrong time can lead to root rot and stunted growth.

Morris Hankinson, Director of Hopes Grove Nurseries explains, ‘Just like most perennials, planting crowns in autumn or spring is generally advised. If planting in autumn, make sure the soil is well drained and mulch the crown to protect it from frosts.’

However, they’re also some of the best bulbs to plant in February if you add them to pots. If you plant the crown around 8-10cm deep in your pots and keep it in full sun, they should be able to survive the colder temperatures.

Morris Hankinson

Morris Hankinson is the founder and managing director of Hopes Grove Nurseries Ltd, the UK’s only specialist grower-retailer of hedging plants. He established the thriving business in 1992, shortly after graduating with a Commercial Horticulture Degree from Writtle College, Essex.

If you’re planting agapanthus roots in the ground, though, it’s probably best to wait until March or even early April to do this. Just make sure that you don’t plant them in the shade, as you might not achieve the results you were hoping for.

This is echoed by Morris, who says, ‘The better time is spring when all frosts have passed,’ he explains. ‘Young crowns can rot in wet weather so by leaving it until springtime, the plants will have time to establish and grow without having to deal with frosts.’

You should also be patient when planning agapanthus. Morris warns, ‘Don’t be too worried if they don’t flower immediately as they can take a few years to establish and flower, but they are well worth the wait!’

Where to buy bare-root agapanthus:

• Thompson & Morgan: Buy the blue and white collection of bare-root agapanthus.
• Crocus: Buy ‘Polar Ice’ bare-root agapanthus for planting in autumn or spring.
• Suttons: Buy six bare-root agapanthus plants to fill your garden.

When to plant agapanthus seeds

If you decided not to deadhead agapanthus and instead chose to let the plants go to seed, you can use them to plant more for free. The plants should start going to seed between late summer and early autumn.

When you spot the seeds in their pods, all you need to do is give them a little push to free them from their casing. When you have them at the ready, you should aim to sow them as soon as possible and keep them under cover until next year. This will give you the best chance of success.

Alternatively, you could hold your horses and wait until spring to sow your agapanthus seeds. You’ll need to store them in an airtight container - like this Kilner Clip Top Round Preserve Jam Jar from Amazon - to ensure they don’t get contaminated, though.

If you buy some online or from the garden centre, it’s also best to wait until the spring - but always double-check the packet to ensure you’re doing right by your specific variety.

Where to buy agapanthus seeds:

• Wilko: Buy ‘Headbourne Hybrid’ agapanthus seeds.
• Mr. Fothergill’s: Buy a pack of 20 agapanthus seeds.
• Gardening Express: Buy agapanthus plants and harvest your own seeds.

FAQs

Where is the best place to plant agapanthus UK?

Although agapanthus plants are fairly low-maintenance, they require well-draining soil and a lot of sunlight to look their best. In fact, they thrive in full sun, and even partial shade can result in stunted growth and poor flowering.

And while agapanthus prefers healthy, well-draining soil, that doesn’t mean that you can’t grow agapanthus in clay soil. As Morris from Hopes Grove Nurseries explains, ‘They will grow on heavier soils but make sure you fork in lots of grit to improve drainage before planting.'

Can you leave agapanthus in the ground over winter?

Although you can technically leave agapanthus in the ground over winter, they don’t love the cold and frosty conditions. Because of this, you always run the risk of your in-ground agapanthus plants dying over the winter months. So, whether you do so is up to you.

A way to combat this is to plant any plants you plan to leave outside over winter in containers. Morris echoes this, saying, ‘They will need protection during the colder months of the year, so ideally plant these into containers so you can easily fleece them.’

So, now you know when to plant agapanthus all you need to decide now is how you’re going to plant it…