Table of Contents
- Introduction
- Understanding Canna Rhizomes
- How Deep Do I Plant Canna Lily Bulbs?
- Orientation: Which Way is Up?
- Spacing for Success
- Choosing the Right Location
- Step-by-Step Planting Guide
- Growing Cannas in Containers
- Aftercare: Helping Your Cannas Thrive
- Overwintering: What to Do in the Fall
- Choosing Varieties for Your Garden
- Dealing with Common Questions
- Conclusion
- FAQ
Introduction
There is something truly magical about the way canna lilies transform a summer garden into a lush, tropical oasis. With their bold, paddle-shaped leaves and vibrant, orchid-like blooms, these plants bring a high-energy "vacation vibe" to any backyard. Whether you are planting them to create a dramatic privacy screen or adding dwarf varieties to your patio containers, the excitement of seeing those first colorful spikes emerge is one of the many joys of gardening.
At Longfield Gardens, we want to help you make the most of these spectacular tropicals. Getting your cannas off to a strong start begins with understanding their unique needs beneath the soil. While they are often referred to as "bulbs," cannas actually grow from thick, fleshy structures called rhizomes. Planting them at the correct depth is the first step toward a season filled with lush foliage and continuous flowers.
This guide is designed for home gardeners who want clear, practical advice on how to plant cannas for the best results. We will cover the ideal planting depth, how to space your rhizomes, and how to choose the best location in your yard. By following a few simple steps, you can enjoy these tropical beauties from the heat of midsummer all the way until the first frost.
Understanding Canna Rhizomes
Before we dig into the specifics of planting depth, it helps to understand what you are holding in your hand. Most gardeners use the word "bulb" as a catch-all term for any plant with an underground storage organ. However, cannas grow from rhizomes. A rhizome is a modified stem that grows horizontally under the soil surface.
If you look closely at a canna rhizome, you will see small bumps or points. These are called "eyes," much like the eyes on a potato. Each of these eyes has the potential to grow into a new stalk. Because they are stems rather than true bulbs (like tulips or daffodils), they have a slightly different growth habit. They like to spread outward, which is why giving them the right amount of room and the proper depth is so important for their long-term health.
When your order arrives from us, you might notice that the rhizomes are firm and fleshy. This is a sign of a healthy plant ready to grow. They are packed with energy to help the plant push through the soil and establish a strong root system. Understanding this horizontal growth habit makes it much easier to visualize how they should sit in the planting hole.
How Deep Do I Plant Canna Lily Bulbs?
The most common question we receive about these tropical favorites is: "How deep do I plant canna lily bulbs?" The short answer is that canna rhizomes should be planted 4 to 5 inches deep.
This depth is measured from the top of the rhizome to the soil surface. Planting at this specific depth provides several benefits that ensure your plants stay healthy and upright throughout the summer.
Why 4 to 5 Inches is the Sweet Spot
Finding the right depth is about balancing the plant's need for stability with its need for warmth. If you plant a rhizome too shallowly—for example, only one or two inches deep—the plant may struggle to stay upright. Canna lilies can grow quite tall, with some varieties reaching five or six feet. As the foliage becomes heavy and catches the summer breeze, a shallow root system might not be enough to keep the plant from leaning or even toppling over.
On the other hand, planting too deep can cause its own set of challenges. If a rhizome is buried 8 or 10 inches deep, it will take much longer for the sun to warm the soil around it. Since cannas are tropical plants that crave heat, deep planting can significantly delay the appearance of those first green shoots. In regions with shorter growing seasons, every week of warmth matters. A depth of 4 to 5 inches ensures the plant is deep enough to be stable but shallow enough to feel the sun's warmth and start growing early in the season.
Soil Temperature and Timing
It is important to remember that depth and timing go hand-in-hand. Even if you plant at the perfect 4-inch depth, the rhizome will stay dormant until the soil is warm. We recommend waiting to plant your cannas outdoors until the danger of frost has passed and the soil temperature has reached at least 60°F.
A simple way to test this is by feeling the soil with your bare hand. If it feels uncomfortably cold, it is too early for cannas. They prefer "warm toes." If you live in a cold climate and want to get a head start, you can plant your rhizomes in pots indoors about 4 to 6 weeks before the last frost date. This gives them a chance to wake up in a controlled environment before moving into the garden.
Orientation: Which Way is Up?
Once you have dug your hole to the correct depth, you need to place the rhizome inside. Because canna rhizomes are horizontal stems, they should be laid flat (horizontally) in the planting hole.
Look for the "eyes" or the small growing points on the rhizome. Ideally, these eyes should be facing upward or toward the side. If you cannot tell which side is the top, do not worry. Plants have an incredible natural ability to sense gravity and light. If a rhizome is planted "upside down," the shoots will simply grow around the side of the rhizome and head toward the surface. However, laying it horizontally with the eyes pointing up gives the plant the most direct path to the sun.
Key Takeaway: Plant canna rhizomes 4 to 5 inches deep and lay them horizontally in the hole. If you can see the growing points (eyes), aim them toward the sky for the fastest growth.
Spacing for Success
Knowing how deep to plant is vital, but knowing how much space to leave between plants is just as important. Cannas are vigorous growers. Over a single summer, one small rhizome can grow into a large, multi-stemmed clump.
Standard and Tall Varieties
For standard cannas that grow 4 feet tall or higher, space the rhizomes about 1 to 2 feet apart. This might seem like a lot of empty space when you first plant them, but you will be surprised at how quickly they fill in. Proper spacing allows for good air circulation, which helps prevent foliage issues and ensures every leaf gets enough sunlight.
Dwarf Varieties
Dwarf cannas, which usually stay between 2 and 3 feet tall, can be spaced a bit closer. Aim for about 1 foot between these smaller varieties. They are excellent for the front of a flower bed or for creating a dense, colorful border.
Creating a Mass Effect
If you want to create a solid screen or a "hedge" of cannas, you can lean toward the closer end of the spacing range (about 12 to 15 inches apart). This will result in the leaves overlapping, creating a beautiful wall of tropical foliage that provides privacy and a stunning backdrop for other flowers.
Choosing the Right Location
To get the most out of your cannas, you need to match their needs to the right spot in your yard. The best planting depth in the world won't help if the plant is in the wrong environment.
Sun Requirements
Cannas are sun-worshippers. To produce those vibrant flowers and maintain deep, rich foliage colors (especially the bronze and variegated types), they need full sun. This means a spot that receives at least 6 to 8 hours of direct sunlight every day. If they are planted in too much shade, they tend to become "leggy," stretching toward the light, and they will produce far fewer flowers.
Soil and Drainage
"Drainage" simply refers to how fast water moves through the soil. While cannas love moisture and can even handle "wet feet" better than many other garden plants, they do best in soil that is rich and well-draining. They are heavy feeders, meaning they appreciate soil that is high in organic matter.
Before planting, you can improve your soil by mixing in some compost or well-rotted manure. This helps the soil hold onto the moisture cannas need while providing a steady supply of nutrients. If your soil is very heavy clay, planting your cannas in raised beds can help ensure the rhizomes don't sit in stagnant water during a particularly rainy spring.
Step-by-Step Planting Guide
Now that we have covered the basics of depth, spacing, and location, let’s walk through the actual process of getting your cannas into the ground.
- Prepare the Spot: Clear away any weeds or debris. Dig a hole or a trench about 6 inches deep. This allows you to loosen the soil at the bottom so the roots can easily penetrate.
- Amend the Soil: If your soil is poor, add a handful of compost to the bottom of the hole and mix it in.
- Check the Depth: Measure from the surface. You want the rhizome to sit so that there will be 4 to 5 inches of soil covering it.
- Place the Rhizome: Lay the rhizome horizontally. If you see eyes or sprouts, point them up.
- Cover and Firm: Fill the hole with soil. Gently press down with your hands to remove any large air pockets. You don't need to pack it down hard; a light touch is enough to ensure the rhizome is in contact with the soil.
- Water Well: Give the area a good soaking immediately after planting. This "settles" the soil around the rhizome and wakes the plant up.
- Label Your Varieties: If you are planting different colors or heights, use a small garden marker to remember what is where. It can take a few weeks for the first shoots to appear, and it's easy to forget which variety is in which spot!
Growing Cannas in Containers
Cannas are fantastic container plants. They add height and drama to patio arrangements and can be moved around to catch the best sun. The rules for planting depth in containers are very similar to planting in the ground, but there are a few extra tips for success.
Pot Size Matters
Because cannas grow large and have vigorous root systems, they need plenty of room. A 12-inch diameter pot is the minimum size for a single dwarf canna. For standard or tall varieties, a 15- to 18-inch pot (or a large half-barrel) is a better choice. Make sure the container has drainage holes in the bottom so excess water can escape.
Depth in Containers
You should still aim to plant the rhizome 4 inches deep in a container. Use a high-quality potting mix rather than garden soil. Potting mix is lighter, drains better, and is free of weed seeds.
Container Care
Plants in containers dry out much faster than those in the ground. During the heat of the summer, you may need to water your potted cannas every day. Because you are watering frequently, nutrients will wash out of the soil faster, so a regular application of a balanced liquid fertilizer every few weeks will keep them blooming and lush.
What to do next:
- Choose a sunny spot that gets 6+ hours of light.
- Wait for the soil to warm to 60°F before planting.
- Dig your hole 4–5 inches deep.
- Space rhizomes 1–2 feet apart.
- Water deeply right after planting.
Aftercare: Helping Your Cannas Thrive
Once your cannas are in the ground and growing, they are relatively low-maintenance. However, a little extra attention will result in bigger blooms and healthier foliage.
Watering Correctly
Cannas are thirsty plants. They have large leaves that lose moisture quickly in the sun. The best rule for watering is "deep, then let it dry a bit." Instead of a light sprinkle every day, give them a deep soak once or twice a week (more often in extreme heat or for container plants). This encourages the roots to grow deeper into the soil, making the plant more resilient.
Feeding Your Plants
Because cannas grow so much biomass in a single season, they need plenty of fuel. We recommend using a balanced, all-purpose fertilizer. Follow the instructions on the product label for application rates. Starting your feeding routine once the plants are about 6 inches tall and continuing through midsummer will ensure they have the energy to keep producing new flower spikes.
Deadheading
"Deadheading" is the simple act of removing faded flowers. For cannas, this isn't just about keeping the plant looking tidy. When you remove a spent flower head, it prevents the plant from putting energy into producing seeds. Instead, that energy is redirected back into the rhizome and toward the development of new flower buds. To deadhead a canna, simply cut the flower stalk back to the next set of leaves or the next visible bud.
Overwintering: What to Do in the Fall
In most parts of the United States, cannas are considered tender perennials. This means they can stay in the ground year-round in warm climates (USDA zones 8–10), but they will not survive freezing winter temperatures in the ground in colder regions (zones 7 and lower).
If you live in a cold area, you don't have to lose your plants! You can dig up the rhizomes and store them indoors for the winter. This is a very rewarding part of growing cannas because the rhizomes usually multiply, giving you even more plants to enjoy next year.
When to Dig
Wait for the first light frost to blacken or wilt the foliage. This frost acts as a signal to the plant that it is time to go dormant. After the frost, cut the stalks down to about 2 to 4 inches above the ground.
Digging and Cleaning
Using a garden fork or a shovel, carefully dig around the clump, being careful not to slice into the fleshy rhizomes. Lift the entire clump out of the ground and gently shake off the excess soil. You can rinse them with a hose if the soil is very sticky, but it isn't strictly necessary.
Curing and Storing
Let the rhizomes "cure" or air-dry in a frost-free, well-ventilated area (like a garage or shed) for a few days. This helps the outer skin toughen up. Once dry, place the rhizomes in a box or a ventilated bag filled with slightly damp peat moss, perlite, or vermiculite.
Store the box in a cool, dark place that stays between 40°F and 50°F. A cool basement or a crawl space is often ideal. Check on them once or twice during the winter; if the storage medium feels bone-dry, you can give it a tiny mist of water, but be careful not to make it wet, as this can cause rot.
Choosing Varieties for Your Garden
Cannas come in a stunning array of colors and patterns. At Longfield Gardens, we offer several classic and unique varieties that are proven performers in the home garden. When choosing, consider both the flower color and the foliage.
- Tall and Dramatic: Varieties like ‘Red King Humbert’ are famous for their dark, bronze-colored foliage and bright red flowers. They make an incredible focal point in the center of a flower bed.
- Classic Brights: ‘The President’ is a beloved variety with bright green leaves and large, scarlet flowers. It is a reliable grower that brings a traditional tropical look.
- Sunny Yellows: For a splash of brightness, ‘Richard Wallace’ offers beautiful canary-yellow blooms against emerald-green leaves.
- Soft Pinks: If you prefer a softer palette, ‘City of Portland’ features lovely coral-pink flowers that look stunning during the "golden hour" of the evening.
By mixing different heights and colors, you can create a layered look that stays interesting from early summer until the end of the season.
Dealing with Common Questions
Sometimes, even with the best care, you might notice something unexpected in the garden. Most canna issues are easy to resolve by adjusting the environment.
Why aren't my cannas blooming?
The most common reason for a lack of flowers is a lack of sunlight. If your plants are in a shady spot, they will focus on growing leaves rather than flowers. Another reason could be a lack of nutrients; a quick boost of fertilizer can often jumpstart the blooming process. Finally, make sure you aren't over-fertilizing with too much nitrogen, which encourages leaves at the expense of flowers.
My plants are leaning. What should I do?
Leaning usually happens if the plants aren't getting enough sun (they are "reaching") or if they were planted too shallowly. If it's a depth issue, you can add a layer of mulch or soil around the base to provide more support, or use decorative bamboo stakes to help hold them up during a stormy week.
The leaves have holes in them.
This is often caused by canna leaf rollers or slugs. A quick inspection in the evening can help you spot the culprits. Maintaining a clean garden space and removing any heavily damaged leaves can help keep the plants looking their best.
Conclusion
Planting canna lilies is one of the easiest ways to bring high-impact color and a tropical feel to your home landscape. By remembering the simple rule of planting your rhizomes 4 to 5 inches deep, you provide your plants with the stability and warmth they need to thrive. Whether you plant them in large garden beds or stylish patio pots, these vigorous growers will reward you with a spectacular display of foliage and flowers all summer long.
At Longfield Gardens, we believe that gardening should be a rewarding and enjoyable experience for everyone. By getting the basics right—like planting depth, sun exposure, and timing—you set the stage for a successful and beautiful season.
- Planting Depth: 4 to 5 inches deep.
- Orientation: Lay rhizomes horizontally with eyes facing up.
- Timing: Wait for warm soil (60°F+).
- Care: Full sun, regular water, and occasional feeding.
Growing cannas is a wonderful way to watch the power of nature in your own backyard. These plants are resilient, fast-growing, and absolutely stunning. We invite you to explore our collection of premium canna rhizomes and start planning your own tropical retreat today.
FAQ
Can I plant canna bulbs in the shade?
Cannas really need full sun to perform their best. While they may grow in partial shade, they will likely be shorter, have fewer flowers, and the foliage colors will not be as vibrant. For the best results, aim for a spot that gets at least 6 hours of direct sunlight.
What happens if I plant my canna rhizomes too deep?
If you plant them much deeper than 5 inches, the soil stays cooler, which can significantly delay the time it takes for the plant to sprout. In regions with short summers, this might mean you get very few flowers before the first frost arrives in the fall.
Do I need to soak canna rhizomes before planting?
Soaking is not strictly necessary for canna rhizomes. As long as you water them well immediately after planting, they will have plenty of moisture to begin their growth cycle. If the rhizomes appear extremely dry or shriveled when you receive them, a 20-minute soak in lukewarm water can help "wake them up," but firm, healthy rhizomes can go straight into the ground.
How many cannas should I plant together?
For a high-impact look, it is often best to plant them in groups of three or five. This creates a dense "clump" of color that looks more natural and intentional than a single lonely stalk. Just remember to leave about 12 to 18 inches of space between each rhizome to allow for their summer expansion.