Introduction
There is something undeniably exciting about adding a touch of the tropics to a backyard garden. Canna lilies, with their massive, paddle-shaped leaves and neon-bright blooms, turn any ordinary border into a lush sanctuary. At Longfield Gardens, we love these plants because they are high-impact and incredibly easy to grow, provided you get the timing right. Whether you are a beginner or an experienced gardener, seeing those first thick, red-tipped shoots poke through the soil is a signal that summer is officially on its way.
Timing is the most important factor when it comes to successfully growing cannas. Because they are native to warm, tropical regions, they have very specific needs regarding temperature and light. This guide will help you determine the best time to get your canna lily rhizomes (often called bulbs) into the ground or started in pots. We will also cover how to prepare your site and what to do if you live in a cooler climate with a shorter growing season. If you are planning your order, start with the Canna Assorted Collection.
Understanding the relationship between soil temperature and plant health is the key to unlocking a season full of vibrant color. For regional timing, the Hardiness Zone Map is a helpful place to begin.
The Golden Rule: Soil Temperature Matters Most
When people ask "when can I plant my canna lily bulbs," the most accurate answer isn't a date on the calendar, but a reading on a thermometer. Cannas are tropical perennials, meaning they thrive in heat and have no natural defense against freezing temperatures. To get them off to a strong start, you must wait until the soil has warmed up significantly.
The magic number for cannas is 60°F (15°C). While some hardy spring bulbs like tulips or daffodils prefer cold soil to develop their roots, cannas will simply sit dormant—or worse, rot—if the ground is too cold and wet. In most parts of the United States, soil reaches this temperature about the same time you would feel comfortable planting tomatoes or basil outside. For shipping timing by zone, see Shipping Information.
To check your soil temperature, you can use a simple soil thermometer. Dig a small hole about two to three inches deep and insert the thermometer. It is best to check in the morning for a few days in a row to get a consistent average. Once the ground stays at 60°F or higher, it is safe to plant your rhizomes directly into the garden.
Timing Your Planting by USDA Hardiness Zone
While soil temperature is the ultimate guide, your USDA hardiness zone provides a helpful window for when those temperatures usually occur. Because the United States has such a wide range of climates, the "right" time to plant in Georgia is very different from the right time in Minnesota.
Zones 8 to 11
In these warmer regions, cannas are often treated as permanent residents of the garden. They can stay in the ground year-round. If you are planting new rhizomes, you can usually start as early as March or April. The ground in these zones rarely stays cold enough to damage the rhizomes once the spring sun begins to hit the earth.
Zones 6 to 7
In these mid-latitude regions, the soil typically reaches the 60°F mark in late April or early May. It is crucial to wait until the danger of a late-season frost has completely passed. If a surprise frost hits after the plants have sprouted, the tender new foliage will turn black and die back. While the rhizome underground will usually survive and send up new shoots later, it sets the plant back several weeks.
Zones 3 to 5
For our friends in the North, the growing season is short. Soil may not naturally reach 60°F until June. Because cannas take about 10 to 12 weeks to go from planting to blooming, waiting until June to plant outdoors might mean you only get a few weeks of flowers before the autumn frost arrives. In these zones, we highly recommend "pre-starting" your cannas indoors, which we will explain in detail below.
Key Takeaway: Always prioritize soil temperature over the date. If the spring is unusually cold and rainy, wait an extra week or two. Patience results in faster growth once the heat finally arrives.
Starting Cannas Indoors for an Early Head Start
If you live in a northern climate or simply want your garden to look lush and full as early as possible, starting your cannas indoors is a fantastic "easy win." This process allows the rhizomes to wake up and begin developing a root system and early sprouts in a controlled, warm environment.
We suggest starting this process about four to six weeks before your region's average last frost date. By the time the weather is warm enough to move them outside, you will have established plants that are already several inches tall, giving you a significant head start on the blooming season.
How to Start Indoors
- Choose your containers: Use pots that are at least 6 to 8 inches deep with excellent drainage. Drainage simply refers to how easily water flows through the soil; you want the water to exit the bottom of the pot rather than sitting in a puddle around the rhizome.
- Use high-quality potting mix: Fill your pots with a standard, well-draining potting soil. Avoid using heavy garden soil, which can pack down too tightly in a container.
- Plant the rhizome: Lay the rhizome horizontally in the pot. If you see small bumps or "eyes" (growth points), point them upward. Cover with about two inches of soil.
- Provide heat and light: Place the pots in a warm spot, ideally between 70°F and 75°F. A sunny windowsill works, but a grow light or the top of a refrigerator can also provide the consistent warmth needed to trigger growth.
- Water sparingly at first: Cannas don't need much water until they start growing. Keep the soil slightly damp, but not wet. Once you see a green shoot emerge, you can begin watering more regularly.
Selecting the Right Place in Your Garden
Getting the timing right is the first step, but "right plant, right place" is the secret to long-term success. Once your soil is warm and your plants (or rhizomes) are ready to go outside, you need to pick a spot that meets their tropical requirements.
Sunlight Needs
Cannas are sun-worshippers. To produce those massive leaves and brilliant flowers, they need at least six to eight hours of direct, unfiltered sunlight every day. If they are planted in too much shade, they will become "leggy," meaning they grow tall and thin as they stretch toward the light. Shaded cannas also produce fewer flowers and may lose the vibrant colors in their foliage.
Soil and Drainage
While cannas love moisture, they do not like to sit in stagnant, soggy water. The ideal soil is rich in organic matter—like compost or well-rotted manure—and allows excess water to drain away. If you have heavy clay soil that stays wet for days after a rain, consider planting your cannas in raised beds or large containers to improve the environment around the roots. If you want more background on planting and care, the Learn hub is a useful reference.
Wind Protection
Because cannas have such large, soft leaves, they can sometimes be damaged by strong, persistent winds. If possible, plant them near a fence, a wall, or a group of sturdy shrubs that can act as a windbreak. This keeps the foliage looking pristine and prevents the tall flower stalks from leaning or snapping.
How to Plant Canna Rhizomes Step-by-Step
When the time is right and the spot is picked, the actual planting process is very straightforward. You don't need fancy tools or complicated techniques to get great results.
- Loosen the soil: Use a shovel or garden fork to loosen the soil to a depth of about 10 to 12 inches. This makes it easier for the new roots to spread out and establish themselves.
- Amend if necessary: If your soil is sandy or lacks nutrients, mix in a few inches of compost.
- Dig the hole: For most varieties, a hole 4 inches deep is perfect.
- Space them out: Cannas grow quickly and need room to breathe. Space small or dwarf varieties about 12 inches apart. For the tall, traditional varieties, give them 18 to 24 inches of space.
- Set the rhizome: Place the rhizome in the hole horizontally. Don't worry too much about which side is up; the plant is smart enough to send roots down and shoots up. However, if you see the "eyes," pointing them toward the sky gives them a slightly faster start.
- Cover and firm: Fill the hole with soil and press down gently with your hands to remove any large air pockets.
- Water in: Give the area a thorough soaking to settle the soil around the rhizome.
What to Do Next:
- Mark the spot with a garden stake so you don't accidentally dig them up before they sprout.
- Check the soil every few days; it should feel like a wrung-out sponge—moist but not dripping.
- Be patient! Cannas can take three weeks or more to show their first green tips above the soil.
Water and Fertilizer: The Fuel for Growth
Cannas are "heavy feeders," which is a gardening term for plants that need a lot of nutrients and water to reach their full potential. Because they grow so much biomass in a single season—often reaching 5 or 6 feet in height—they require consistent "fuel."
Watering Correctly
During the heat of summer, cannas are very thirsty. Unlike succulents or some drought-tolerant perennials, cannas will wilt and stop blooming if they dry out completely. A good rule of thumb is to give them a deep soaking once or twice a week. If you are growing cannas in containers, you may need to water them every day during July and August, as pots dry out much faster than the ground.
Fertilizing for Success
To keep the flowers coming all summer long, we recommend using a balanced, water-soluble fertilizer every few weeks. Alternatively, you can apply a slow-release granular fertilizer at the time of planting. Look for a fertilizer that is designed for flowering plants or even one meant for tomatoes; these usually have the right balance of nitrogen for leaf growth and phosphorus for flower production.
Understanding Variety: Dwarf vs. Tall Cannas
When planning your garden and deciding when and where to plant, it helps to know which type of canna you are growing. While their care requirements are mostly the same, their size affects how you use them in the landscape. If you want a ready-made mix, the Assorted Cannas collection is a convenient place to start.
Tall Varieties
These can reach heights of 5 to 8 feet. They are spectacular when used as a "living screen" or as a backdrop for shorter flowers. Because they grow so large, they are the most sensitive to wind and require the most water and nutrients. Examples include those with classic green or deep burgundy foliage. For the biggest impact, browse the Tall Cannas collection.
Dwarf and Medium Varieties
These typically stay between 2 and 4 feet tall. They are perfect for the middle of a flower bed or for growing in pots on a patio. Because they are more compact, they often start blooming a little earlier in the season than the towering giants. If you have a small space or a shorter summer, dwarf varieties are often the best choice. For a single standout variety, Canna Tall Tropicanna is a striking option.
Common Timing Mistakes to Avoid
Even though cannas are resilient, a few common mistakes can slow them down or prevent them from blooming.
- Planting too early: This is the most frequent issue. If the soil is 50°F instead of 60°F, the rhizome will simply sit in a dormant state. If the spring is wet, that dormant rhizome is highly susceptible to rot. It is always better to wait for the heat.
- Forgetting to harden off: If you started your plants indoors, you cannot move them directly into the hot sun and wind. They need a transition period called "hardening off." Spend 7 to 10 days moving them outside for a few hours at a time, gradually increasing their exposure to the elements.
- Inconsistent watering: If a canna goes through a period of extreme drought followed by heavy water, it can stress the plant. This stress often causes the flower buds to drop before they open. Aim for consistent moisture.
The "When" of the End: Overwintering Your Cannas
The question of "when can I plant" is naturally followed by "when do I take them out?" If you live in Zone 7 or colder, your cannas will not survive the winter outdoors without help.
In these regions, you should wait until the first light frost kills the foliage. The leaves will turn brown or black and look wilted. This is actually a good thing! It signals the plant to move all its energy down into the rhizome for storage. Once this happens, cut the stalks down to about 4 inches above the ground.
Carefully lift the rhizomes with a garden fork, being careful not to bruise or cut them. Shake off the excess soil and let them "cure" in a dry, shady spot for a few days. Once they are dry to the touch, store them in a cool, dark place (like a basement or crawlspace) inside a box filled with slightly damp peat moss or perlite. The temperature should stay between 40°F and 50°F—cool enough to stay dormant, but warm enough to stay alive.
Enjoying the Rewards of Your Efforts
One of the best things about cannas is how they attract wildlife. Hummingbirds and butterflies are naturally drawn to the tubular, nectar-rich flowers. By getting your timing right and providing the warm environment these plants crave, you are creating a vibrant ecosystem in your own backyard.
At Longfield Gardens, we believe that gardening should be a rewarding experience rather than a stressful chore. Cannas are the perfect example of this. They ask for very little—just some sunshine, a bit of water, and the right starting temperature—and in return, they give you a summer-long show that is truly spectacular.
Key Takeaway: Success with cannas is a journey of warmth. From the 60°F soil at planting to the hot summer sun that fuels their blooms, these plants thrive when they are given the heat they love.
Summary of the Canna Planting Timeline
To make your planning as easy as possible, here is a quick reference for your canna season:
- Late Winter/Early Spring: Order your rhizomes and check your USDA zone.
- 4-6 Weeks Before Last Frost: Start rhizomes in pots indoors if you live in a cold climate.
- After Last Frost (Soil 60°F): Move plants outside or plant rhizomes directly into the garden.
- Early Summer: Begin regular fertilizing and ensure consistent watering.
- Mid to Late Summer: Enjoy the peak bloom period and deadhead spent flowers to encourage more growth.
- After First Autumn Frost: Cut back foliage and lift rhizomes for winter storage in cold zones.
Conclusion
Planting canna lilies is one of the easiest ways to transform your landscape into a tropical paradise. By focusing on the "when"—waiting for that crucial 60°F soil temperature—you ensure that your plants have the best possible start. Whether you choose to plant them directly in the earth or give them a head start indoors, the result is the same: a summer filled with bold textures and breathtaking color.
At Longfield Gardens, we are here to help you grow a garden you love. We stand behind the quality of our rhizomes and want to ensure you have all the support you need for a successful growing season. Remember that gardening is an adventure, and while weather can be unpredictable, following these basic timing rules will put you well on your way to success. If you want more planting guidance, explore the Learn page.
Get your garden ready for the heat! Once the soil stays warm, you are just a few weeks away from the spectacular, tropical display that only canna lilies can provide.
FAQ
Can I plant cannas if it is still raining a lot in the spring?
It is best to wait until the soil is both warm and not overly saturated with water. If the soil is "muddy" rather than "moist," the rhizomes are at a higher risk of rotting before they can start growing. Wait for a window of drier weather once the temperatures have reached 60°F.
How long does it take for canna lily bulbs to bloom after planting?
On average, cannas take about 10 to 12 weeks to bloom when planted from a dormant rhizome. If you start them indoors 4 to 6 weeks early, you can often see flowers much sooner, sometimes by early to mid-July depending on your local sun and heat.
What happens if I plant my cannas too deep?
If cannas are planted too deep (more than 6 inches), they may struggle to push their shoots through the soil. This can lead to delayed growth or even rot. Sticking to a planting depth of 2 to 4 inches is the best way to ensure the shoots can easily reach the sunlight.
Do I need to soak canna rhizomes before planting them?
While not strictly necessary, soaking your rhizomes in lukewarm water for a few hours before planting can help "wake them up" and hydrate the tissues. This can sometimes lead to slightly faster sprouting, but you will still have great results if you skip this step and plant them directly into moist soil.
