How deep should you plant tulip bulbs? Professional gardeners reveal the best depth for guaranteed blooms
It's nearly tulip planting season, which means there's no better time to brush up on your bulb knowledge
Despite tulips being one of the most popular plants to add to your garden, it's easy to get planting wrong. And the depth at which you plant the bulbs is one of the first hurdles.
When it comes to learning how to grow tulips, there aren't many ways you can go wrong; however, there are several instances where specialist knowledge is needed. And before you worry about caring for your growing tulips, you'll need to ensure the bulbs are planted properly.
It may seem like an insignificant point, but planting your tulip bulbs too deep or too shallow is integral for their growing potential. So, to ensure you have impressive blooms come spring, we spoke with gardening professionals to find out what depth is just right.
How deep should you plant tulip bulbs?
Similar to planting your tulip bulbs too late, misjudging the depth at which you plant bulbs can also prove problematic.
"Whether you are planting tulip bulbs into pots or directly into the ground, you must plant them to around three times the height of the bulb itself," says Lucie Bradley, gardening expert at Easy Garden Irrigation. "Which usually means between 15 and 20 cm from the surface."
"The reason behind why tulip bulbs are planted deeper than many other spring-blooming bulbs like crocus or daffodils is that it helps to protect them from the colder winter weather and frosts, as well as providing the depth that they need to produce deep roots, which can keep their stems upright and able to support their heavy blooms," she adds.
That's why tulips are not generally a plant you need to support while they grow; they do that all on their own when planted deep enough.
How many tulip bulbs do you put in one hole?
You may think more bulbs in one hole means more flowers, but sadly that's not quite how it works.
"Depending on how you want your tulips to appear in your garden, you can either plant them as single bulbs – placing one bulb in its own hole and spacing these approx. 10 to 15cm apart if you want to create a formal display," explains Lucie.
"For more informal, natural planting, tulips can be grown in clusters - known as ‘bouquet’ planting. This involves digging one hole approx. 25 to 30cm wide and then adding between 5 and 7 bulbs so that they are spaced around 3 to 5cm apart," she adds.
You'll also have to take this into consideration if you're trying out Monty Don's bulb lasagne method, which tulips are perfect for.
With over 28 years working in the garden industry, Lucie has been fortunate enough to spend every day speaking to both amateur and professional gardeners. Encouraged to garden since she was old enough to walk, she believes that you can never know everything about gardening, as it is constantly evolving.
Will tulips grow if not planted deep enough?
If you don't avoid this autumn gardening mistake and accidentally plant your tulip bulbs too shallow, don't worry; you will still get flowers.
"If you plant your tulip bulbs too close to the surface of the ground, this won’t stop them from growing and producing blooms, but it will negatively affect their health, their stability and leave them more vulnerable to pest damage," says Lucie.
"Your tulip bulbs will be more vulnerable to changes in temperature when planted close to the surface of the ground, so can be damaged by frost, which can cause the bulbs to dry out as they lack the insulation and moisture they gain from the soil when planted at the correct depth," she continues.
If you do manage to protect your plants from frost, though, shallow planting can lead to other more serious issues.
"With many tulips reaching 50cm or more in height, it’s important that they produce a strong root system deep in the soil to securely anchor them in place," says Lucie. "If you don’t plant your tulips deep enough, they won’t be able to develop the deep roots which they need to keep their stems steady.
In addition, with less soil covering the bulb, there is less weight to support the stems. "As a result, your tulips are likely to finish up leaning or even falling over when in bloom."
"When planted close to the surface of the ground, leaves tulip bulbs within easy reach of wildlife. Tulip bulbs taste sweet, being packed full of sugar, starch and carbohydrates and don’t have the same bitter toxins that daffodils or alliums use for natural pest defence, so squirrels, voles and muntjac will easily detect their scent and eat these nutrient-dense morsels before they get a chance to grow," she finishes.
So it's worth putting measures in place to keep squirrels out of your garden while waiting for your tulip bulbs to establish, as they're particularly clever thieves.
Once you've mastered planting your tulips, you can enjoy their blooms, and then all you'll need to know is what to do with them after flowering once spring ends.
