Introduction
Adding a touch of the tropics to your home landscape is one of the most rewarding parts of the summer gardening season. Cannas are the perfect choice for this, offering bold, architectural foliage and vibrant flowers that last from midsummer through the first frost. These plants are known for their resilience and their ability to transform a plain garden bed into a lush, colorful retreat with very little effort.
At Longfield Gardens, we want to make sure you feel confident from the moment your plants arrive at your door, and our Shipping Information page can help you plan ahead. Knowing how deep to plant canna bulbs in the ground is the first step toward a successful season of growth. This guide is designed for home gardeners who want clear, practical advice on getting these tropical beauties into the soil correctly.
Whether you are a first-time gardener or a seasoned pro, understanding the simple mechanics of planting depth and spacing will ensure your cannas grow tall and strong. Proper planting allows the roots to establish quickly and helps the shoots reach the sunlight at just the right time. Getting these basics right at the start of the season sets the stage for a spectacular summer show.
What Are Canna Bulbs?
Before we dig into the specifics of planting depth, it helps to understand what you are actually putting in the ground. While most people refer to them as "bulbs," cannas actually grow from rhizomes. A rhizome is a thick, fleshy underground stem that stores energy for the plant.
When you look at a canna rhizome, you will see small bumps or points. In the gardening world, we call these "eyes." These eyes are the growth points where the new stems and leaves will emerge. Because the rhizome is a storage unit, it provides all the energy the plant needs to send up its first few leaves.
Choosing high-quality rhizomes is the best way to start your garden on the right foot. At Longfield Gardens, we ensure our rhizomes are firm, healthy, and ready to grow, and our 100% Guarantee offers extra peace of mind. When your rhizomes arrive, they should feel heavy for their size and have at least a few visible eyes.
Key Takeaway: Cannas grow from rhizomes, which are thick underground stems. These stems store the energy needed to produce the plant's signature large leaves and bright flowers.
When to Plant Cannas in the Ground
Timing is just as important as depth when it comes to planting cannas. These are tropical plants that thrive in heat and cannot tolerate frost. If you plant them too early in cold, wet soil, the rhizomes may sit dormant for too long.
The best time to plant is when the soil temperature has reached at least 60°F. For most gardeners in the United States, this happens around the same time you would plant tomatoes or peppers. A simple way to check is to wait until the danger of frost has completely passed and the days are consistently warm. If you want a quick reference, our Hardiness Zone Map can help you time planting more accurately.
If you live in a northern climate with a short growing season, you can start your rhizomes indoors in pots about four to six weeks before the last frost. This gives them a head start so they are already growing when it is time to move them into the garden. If you choose to plant directly in the ground, just be patient. Cannas are "sleepers" and can take three weeks or more to show their first green shoots above the soil.
How Deep to Plant Canna Bulbs in the Ground
The most common question for any bulb gardener is "how deep does it go?" For canna rhizomes, the general rule is to cover them with 2 to 4 inches of soil.
This depth provides a few benefits. First, it keeps the rhizome insulated from temperature swings in the early spring. Second, it provides enough soil "weight" to anchor the plant as it grows tall. Some canna varieties, like 'Wyoming' or 'The President', can reach 4 to 6 feet in height. A deep root system is essential to keep these tall plants from leaning or falling over during a summer storm.
Adjusting Depth for Your Soil Type
While 2 to 4 inches is the standard, you can make slight adjustments based on the type of soil in your yard.
- In Sandy Soil: If your soil is very loose and sandy, water moves through it quickly. In this case, planting closer to the 4-inch mark is a good idea. This prevents the rhizomes from drying out too fast and gives them more stability in the loose earth.
- In Heavy Clay Soil: Clay soil holds a lot of moisture and stays cool longer. If you have heavy clay, aim for the shallower end of the scale—about 2 inches of soil covering the rhizome. This allows the sun to warm the soil around the rhizome more quickly, which encourages faster sprouting.
Which Way is Up?
When you place the rhizome in the hole, look for the "eyes" or growth points. These should be facing upward toward the sky. If you cannot tell which side is which, do not worry. You can lay the rhizome on its side (horizontally) in the bottom of the planting hole. Canna rhizomes are very clever; the shoots will naturally find their way up to the light, and the roots will grow down into the earth.
What to do next:
- Wait for soil temperatures to reach 60°F.
- Dig a hole or trench about 4 to 5 inches deep.
- Place the rhizome horizontally with the eyes facing up.
- Cover with 2 to 4 inches of soil.
- Tamp the soil down gently with your hands.
Spacing Your Canna Bulbs
Spacing is just as vital as depth because cannas are vigorous growers. They spread outward through their underground rhizomes and produce large, wide leaves that need room to breathe.
For most standard canna varieties, you should space the rhizomes 18 to 24 inches apart. This might look like a lot of empty space when you first plant them, but you will be surprised how quickly they fill in. Proper spacing ensures that each plant gets enough sunlight and that air can circulate between the leaves. Good airflow is one of the easiest ways to keep your plants healthy and vibrant all summer long.
If you are planting dwarf or compact varieties, such as 'City of Portland' or 'Lucifer', you can space them slightly closer together—about 12 to 15 inches apart. These smaller varieties are excellent for the front of a garden border or for adding a pop of color to the edges of a patio.
Choosing the Best Location
Cannas are sun-seekers. To get the best flowers and the most colorful foliage, you need to find the sunniest spot in your garden. Ideally, they should receive at least 6 to 8 hours of direct sunlight every day. If they are planted in too much shade, they will grow tall and "leggy" as they reach for the light, and they may not produce as many flowers.
In addition to sun, consider the drainage of the area. "Drainage" simply refers to how fast water leaves the soil after a rainstorm. While cannas love moisture and can even grow near the edge of a pond, they do not like to sit in stagnant, soggy puddles for long periods.
If you have a spot where water pools for hours after a rain, you can improve the area by adding organic matter like compost or shredded leaves. This helps fluff up the soil and allows water to move through more easily. Alternatively, you can plant your cannas in raised beds where you have more control over the soil quality.
Preparing the Soil for Planting
You do not need to be a soil scientist to grow great cannas, but a little preparation goes a long way. These plants are "heavy feeders," meaning they use a lot of nutrients to produce those massive leaves and blooms.
Before you plant, it is a good idea to loosen the soil to a depth of about 10 to 12 inches. This makes it much easier for the new roots to spread out and establish themselves. Mixing in a few inches of compost or well-rotted manure will provide a steady supply of nutrients throughout the growing season.
Cannas prefer soil that is slightly acidic to neutral. If you aren't sure about your soil's pH, don't worry too much—cannas are very adaptable. As long as the soil is rich in organic matter and stays consistently moist, they will likely thrive.
Step-by-Step Ground Planting Guide
Ready to get started? Follow these simple steps for planting your canna rhizomes in the garden.
- Clear the Area: Remove any weeds or grass from the planting site so your cannas don't have to compete for water and nutrients.
- Dig the Hole: Dig a hole or a trench. If you are planting a long row of cannas for a privacy screen, a trench is often easier than digging individual holes. Aim for a depth that allows you to cover the rhizome with the recommended 2 to 4 inches of soil.
- Place the Rhizome: Set the rhizome in the hole. If you see eyes, point them up. If the rhizome is long and narrow, lay it flat.
- Cover and Firm: Fill the hole back in with soil. Use your hands to gently press down on the soil. This removes large air pockets and ensures the rhizome is in direct contact with the earth.
- Water In: Give the area a good soaking immediately after planting. This "settles" the plant into its new home and wakes up the rhizome.
Watering and Aftercare
Once your cannas are in the ground, their needs are fairly simple. Because they are tropical plants, they enjoy consistent moisture. During the heat of the summer, you should check the soil regularly. If the top inch of soil feels dry to the touch, it is time to water.
For the best results, water deeply. Instead of a light sprinkle every day, give the plants a long, slow soak once or twice a week. This encourages the roots to grow deeper into the ground, making the plant more resilient during dry spells.
Using a layer of mulch around the base of your plants is a great tip for any gardener. A 2-inch layer of bark mulch, straw, or shredded leaves helps hold moisture in the soil and prevents weeds from popping up. It also gives the garden a clean, finished look.
Fertilizing Your Cannas
Because cannas grow so fast, they benefit from regular feeding. You can use a balanced, slow-release fertilizer at planting time to get them started. Once they are about a foot tall, you can apply a liquid fertilizer every few weeks. This provides the extra energy they need to keep producing new flower spikes all the way into autumn.
Deadheading for More Blooms
"Deadheading" is a gardening term that simply means removing faded flowers. When a flower spike on your canna has finished blooming, you can snip it off. This prevents the plant from putting energy into making seeds and instead encourages it to produce a new flower stalk.
When you snip off the old flowers, be careful not to cut the main stem too low. Often, a new flower bud is already forming just below the old one. Simply remove the individual spent blossoms or the very top of the stalk where the flowers were.
Container Planting Depth vs. Ground Planting
Many gardeners choose to grow cannas in large pots on their decks or patios. This is a fantastic way to add height to a container garden, and our How to Grow Cannas in Containers for Tropical Style guide has more tips for getting started. When planting in pots, the depth rules are very similar to planting in the ground, but there are a few small differences to keep in mind.
In a container, use a high-quality potting mix rather than garden soil. Potting mix is lighter and designed to drain well in a confined space. Plant your rhizomes about 3 to 4 inches deep in the pot.
The biggest difference with container gardening is water. Pots dry out much faster than the ground. During the peak of summer, you may need to water your container-grown cannas every single day. Look for large pots—at least 15 to 18 inches in diameter—to give the rhizomes enough room to grow and to prevent the pot from becoming top-heavy and tipping over.
Key Takeaway: Container-grown cannas need the same 3 to 4 inches of depth as those in the ground, but they require much more frequent watering and a large, heavy pot for stability.
Popular Canna Varieties to Try
Choosing a variety is the most fun part of the process. Cannas come in an incredible range of colors, both in their flowers and their leaves. Here are a few favorites that we often recommend:
- 'Tropicanna': This variety is famous for its multicolored foliage. The leaves feature stripes of green, gold, and pink, topped with bright orange flowers.
- 'Black Knight': For a dramatic look, this variety offers deep burgundy, nearly black foliage and crimson-red flowers. It provides a stunning contrast against green-leaved plants.
- 'Stuttgart': If you like variegated plants, Stuttgart is a showstopper. Its green and white striped leaves are elegant and unique. This variety prefers a bit of afternoon shade to keep the white parts of the leaves from scorching.
- 'Wyoming': A classic tall variety with bronze-toned leaves and vibrant apricot-orange blooms. It is perfect for the back of a flower bed.
- 'City of Portland': The City of Portland variety is a reliable heirloom with coral-pink blooms and strong growth.
- 'Tropicanna': If you want striped foliage with strong color, Canna Tall Tropicanna is one of the most popular choices.
- 'Tropicanna Black': For a darker look, Canna Tall Tropicanna Black adds bold, maroon-black foliage and vivid flowers.
No matter which variety you choose, the planting depth remains the same. You can mix and match different heights and colors to create a layered, professional-looking garden.
Overwintering Your Cannas
Cannas are perennials in warm climates (USDA zones 7 through 11). In these areas, you can leave the rhizomes in the ground all year. Once the foliage turns yellow or brown after the first frost, simply cut the stems down to about 4 inches and cover the area with a thick layer of mulch for the winter.
In colder climates (zones 6 and below), cannas are treated as annuals, or the rhizomes must be "lifted" and stored indoors. This is an easy process that allows you to save your favorite plants for the following year.
- Wait for Frost: Let the first frost blacken the foliage. This tells the plant to go dormant.
- Cut Back: Cut the stems down to about 2 to 3 inches above the ground.
- Dig Carefully: Use a garden fork or shovel to gently lift the clump of rhizomes out of the earth. Start digging about a foot away from the base to avoid slicing the rhizomes.
- Clean and Dry: Shake off the excess soil and let the rhizomes dry in a cool, shaded area for a few days.
- Store: Place the rhizomes in a box filled with peat moss, perlite, or wood shavings. Store the box in a cool, dark place that stays between 40°F and 50°F, such as a basement or crawlspace.
If you want to start with mixed options for your next planting season, the Canna Assorted Collection is a convenient way to try several types at once. In the spring, you can divide the clumps, ensuring each piece has at least one or two "eyes," and start the planting process all over again!
Summary of Success
Growing cannas is a rewarding way to bring big color and a tropical feel to your backyard. By focusing on a few simple basics—planting depth, timing, and sunlight—you can ensure your garden looks its best all season long. Remember that gardening is an adventure, and cannas are some of the most forgiving and enthusiastic partners you can have in the dirt.
As you plan your garden this year, we invite you to explore the wide selection of varieties we offer at Longfield Gardens, starting with our Tall Cannas collection. We are here to help you grow a garden you love, one bulb at a time.
Final Checklist for Canna Success:
- Plant rhizomes 2 to 4 inches deep once soil is 60°F.
- Choose a spot with at least 6 hours of direct sun.
- Space standard varieties 18 to 24 inches apart.
- Keep the soil consistently moist throughout the summer.
- Remove faded flowers to encourage new blooms.
For more information on planning your summer garden or choosing the best plants for your zone, visit our Garden Basics page. We are excited to see what you create!
FAQ
How can I tell which side of the canna rhizome should face up?
Look for the "eyes," which are small, pointed bumps or sprouts on the surface of the rhizome. These should face upward when you place the rhizome in the ground. If you cannot find any eyes, simply lay the rhizome horizontally in the hole, and the plant will naturally grow toward the surface.
Will cannas grow if I plant them deeper than 4 inches?
While cannas are hardy, planting them much deeper than 4 inches can delay their growth. The further down the rhizome is, the longer it takes for the soil to warm it up and for the shoots to reach the sunlight. Aim for the 2 to 4-inch range for the quickest and strongest start.
Do I need to soak canna rhizomes before planting them in the ground?
Soaking is not strictly necessary, but some gardeners find that soaking the rhizomes in lukewarm water for a few hours before planting helps them "wake up" faster. If your rhizomes look very dry or shriveled when they arrive, a short soak can be beneficial. However, if they feel firm and healthy, you can go ahead and plant them directly in moist soil.
Why are my cannas taking so long to sprout after planting?
Cannas are heat-loving plants and are often slow to start if the weather is still cool. It is very common for them to take three to four weeks to show their first green shoots. As long as the soil is warm and you have planted them at the correct depth of 2 to 4 inches, they are likely just waiting for a few more warm days to begin their upward journey.
