Tulip planting depth: How to plant your tulip bulbs for optimal blooms

You’ve purchased a variety of tulip bulbs and you’re excited to dig them into the garden for spring. Besides choosing the right location for your bulbs (more on that in a moment), knowing the recommended tulip planting depth for your particular bulb(s) is an important step.

Plant new bulbs in the ground as soon as possible after they’ve been delivered or after you’ve brought them home from the garden centre. If you need to store bulbs for a couple of days, make sure they’re in a cool, dry location.

It’s generally suggested that you plant your spring-flowering bulbs once nighttime temperatures dip to between 40°F (4°C) and 50°F (10°C). In the growing zone where I live, this is usually around October. You want to plant them in the ground before the soil freezes and to give the bulbs some time to become established. That said, if you forgot about them until the winter, you may still have success if you plant them. If the soil is still workable, I’ve planted bulbs in November and December.

Deciding where to plant your bulbs

Choose an area of the garden that gets full sun in the early spring. Make sure it’s a spot where there is good drainage. Bulbs don’t like shade, heavy clay, or excess moisture. They’ll rot if they’re planted in a garden that is too wet. Bulbs contain all the energy and nutrients they need to bloom in the spring. But it’s a good idea to amend the soil with organic matter, like compost.

Check out the social media accounts and websites for places famous for their spring bulb displays for bulb planting ideas. For me, that’s the Keukenhof in the Netherlands or the Canadian Tulip Festival in Ottawa, Ontario. Their tulip gardens are gorgeous and inspiring. I also recommend the book Colour Your Garden by Jacqueline van der Kloet, who recommends mixing all of your bulbs into these beautiful drifts of mixed blooms.

Determining the right tulip planting depth

Your bulb package should provide all the planting instructions you’ll need. The optimum planting depth is based on the size of the bulb. If the package doesn’t mention tulip planting depth, do an internet search for the variety you’re planting.

The general recommendation for bulb planting is to dig a hole that is equal to three times the height of the bulb. If you have sandy soil, you should plant your bulbs a bit deeper to prevent them from drying out.

Plant bulbs in individual holes or dig a trench if all your bulbs can be planted at the same depth.

Species tulips, which aren’t targeted by squirrels, can be planted more shallowly, generally about 4 (10 cm) to 5 (12.5 cm) inches deep, while mid-sized species, like Tulipa greigii, are planted 6 (15 cm) to 8 inches (20 cm) deep.

As far as spacing goes, large bulbs (2 inches/5 cm) in diameter should be planted 3 (7.5 cm) to 8 (20 cm) inches apart. Small bulbs that are about 1 inch (2.5 cm) wide can be planted 1 (2.5 cm) to 3 (7.5 cm) inches apart.

Measuring tulip planting depth

There are a few handy tools you can use to plant your bulbs. The bulb planter I own has a ruler along the side. I simply push it into the soil to the depth I need it to be. It creates the hole and then brings the soil along as you pull it back out. Squeezing the sides releases the soil into a pile beside the hole that I can later use to fill in the hole.

I’m also fond of my A.M. Leonard soil knife. It’s great at digging holes (especially in hard-packed soil) and it doubles as a ruler. It’s probably my most-used garden tool.

And I love this tip from Jessica: Mark the handle of your shovel with lines at certain depths so you just flip your shovel over to tell how deep the hole is.

Bulb-planting augers are a clever invention that really make digging a cinch. All you need is a power drill. Sometimes it’s a challenge to dig, especially if you have hard-packed or clay soil. Augers are a great way to plant bulbs in the grass, if you’d like to naturalize them in the lawn. The sod is often much tougher to dig than your garden’s soil.

Power Planter augers, for example, come with hex heads that will fit a standard drill chuck. There are even augers that are tall enough they allow you to dig your hole from a standing position! And then all you have to do is drill baby, drill.

Planting tulip bulbs

To plant, dig a small hole and loosen the soil at the base of it. You may even want to dig down an extra two to three inches to give loosen up the soil. This will help root growth.

Add that soil back, so that the depth is accurate for the bulb (measure from the base of the bulb), and plant. When you drop the bulb in, make sure you place it pointy side up. (Though if you do happen to turn it the wrong way, the bulb will often right itself!)

Top-dress your planting area with compost. Water your planting site thoroughly.

Protecting your tulip bulbs from pests

Unfortunately squirrels and chipmunks consider tulip bulbs to be tasty little snacks. When you make your tulip purchase, include a few bulbs they don’t like. Try to surround your tulips with daffodil bulbs, and other bulbs, such as grape hyacinth, crown imperials, and alliums, which are not palatable to four-legged creatures.

Add a layer of leaves to the garden. The organic material will do double duty, helping to nourish the soil and providing a layer of protection. A gardening friend recommended adding some smelly protection. I now sprinkle my bulb-planting area with a hen manure fertilizer after I’ve planted. The squirrels don’t seem to enjoy the scent. Cover your bulbs in a thin layer of mulch. I do this to add a little further protection.

The perils of planting too deeply or too shallow

Your bulbs risk being discovered by squirrels or chipmunks if you plant them in too shallow of a hole. They also could become vulnerable to dramatic changes in the weather that cause sudden thawing and freezing. Furthermore, their root system may not become as robust, which will affect the blooms and the plant development. However if you plant bulbs too deeply, they may not flower—or they will flower too late.

You also want to mind the spacing instructions as planting bulbs too closely together could also lead to problems—the roots strangling each other out, or dehydrating or starving due to lack of water and nutrition.

Watch a brief video about tulip planting depth here:

Looking for more bulb-planting advice, as well as interesting flower bulbs to plant?

• When to plant daffodil bulbs
• The best long-blooming allium varieties
• Deer-resistant bulbs for spring colour in the garden
• Bulb-planting inspiration and design tips from the Keukenhof
• Unusual flower bulbs for your garden
• How and when to fertilize bulbs