How deep to plant allium bulbs for beautiful vibrant blooms in your garden next year

Knowing how deep to plant allium bulbs is an important bout of knowledge if you're currently on the case of filling your garden with beautiful, vibrant blooms.

While you may be clued up on knowing when to plant allium bulbs, all that means nothing if you're not planting them at the correct depth. After all, don't we want to ensure successful growth for our alliums so we can reap the visual benefits when they bloom?

So, what exactly is too deep or too shallow? Here's what you need to know so you can guarantee striking alliums as a part of your scheme next spring and summer and achieve the TikTok viral bulb lawn for yourself.

How deep to plant allium bulbs

'The current time of the year (early to mid-autumn) is the perfect time for planting allium bulbs,' starts Peter Ivanov, gardening and plant expert at Fantastic Gardeners. 

'However, when doing that, it’s essential to keep in mind that the planting depth is very important for their successful growth.'

Peter Ivanov

Peter Ivanov is a gardening and plant expert who has been working at Fantastic Gardeners for 8 years. As one of the company's top-performing experts, he now manages over 6 teams of gardeners, delivering stunning landscape results and fostering a deep connection with nature through his work.

'With this task, you should generally follow a guideline of planting them at a depth that's 4 times the diameter of the bulb,' continues Peter.

'For example, if the bulb is 5 centimetres in diameter, plant it at a depth of approximately 20 or at least 15 centimetres.'

'Planting too shallow can expose the bulbs to extreme temperatures and can result in unstable growth in the long run. On the other hand, planting too deep can hinder the emergence of shoots,' he warns.

However, if you need some extra assurance, Nick Wood, garden designer at GardeningExpress.co.uk assures us that 'planting them too deep is better than planting them too shallow' in the off chance you end up in that situation.

Nick also adds that if you're planting alliums for a container garden, ensure that you have a deep enough pot, like this pack of 5 plant pots for £16.99 at Amazon.

But of course, before even starting on the task of planting allium bulbs, preparation is key.

'Make sure to also prepare the soil as alliums prefer well-draining soil and amending heavy or clayey soil with organic matter, such as compost, will improve the drainage,' advises Peter.

'Then, select a location with full sun exposure because alliums thrive in sunlight, and a sunny location encourages robust flower development.'

'You should also make sure to keep gaps between bulbs, as they need space for their large flower heads and foliage,' adds Nick.

'Small and medium-sized alliums should be planted around 7-10cm apart and larger species need to be at least 20cm apart.'

FAQs

Following these tips will ensure you beautiful blooms come next spring and summer, where you will then be faced with asking yourself, 'Should I deadhead alliums?' once they've flowered.

But, we'll leave that as next year's problem to worry about...