Table of Contents
- Introduction
- Understanding Missouri’s Planting Zones
- The Best Time to Plant Cannas Outdoors
- Starting Cannas Indoors for an Early Start
- Selecting the Right Spot in Your Missouri Garden
- How to Plant Canna Rhizomes: Step-by-Step
- Watering and Feeding for Maximum Growth
- Dealing with Missouri Pests and Challenges
- Enjoying the Blooms and Foliage
- End of Season: What to Do When Frost Hits
- Conclusion
- FAQ
Introduction
There is nothing quite like the sight of a canna lily unfurling its broad, banana-like leaves in the heat of a Missouri summer. These plants bring an immediate tropical flair to our Midwestern landscapes, offering vibrant blooms in shades of red, orange, and yellow that stand tall against the humidity. At Longfield Gardens, we love how cannas transform a standard backyard into a lush retreat with very little effort.
This guide is designed to help Missouri gardeners navigate the specific timing and care requirements needed to succeed with these heat-loving plants. Whether you are gardening in the rolling hills of the north or the warmer Bootheel region, we will cover exactly when to get your rhizomes in the ground and how to keep them thriving. By following a few simple steps, you can enjoy a season full of bold color and architectural interest.
Timing is the most important factor for canna success in the Show-Me State, as these tropical beauties require warm soil and a frost-free environment to truly shine.
Understanding Missouri’s Planting Zones
Missouri is a diverse state when it comes to gardening weather. To know when to plant, you first need to understand your local hardiness zone. Most of the state falls into USDA Zones 5b through 7a. The northern half of the state, including cities like St. Joseph and Kirksville, typically experiences colder winters and later spring frosts. Central areas like Kansas City and St. Louis usually sit in Zone 6, while the southern Ozarks and the Bootheel can reach into Zone 7.
Because cannas are tropical plants, they are not hardy enough to survive a Missouri winter in the ground. In their native environments, they grow year-round, but in our climate, we treat them as tender perennials. This means we plant them in the spring and, for many gardeners, lift them in the fall to save them for the next year.
The key takeaway for any Missouri gardener is that the calendar date is less important than the actual temperature of the soil. While a neighbor might plant their cool-season peas in March, your cannas need to wait for the heat.
The Best Time to Plant Cannas Outdoors
The ideal time to plant canna rhizomes is typically in May. A common rule of thumb used by many experienced gardeners in our state is to wait until after Mother's Day. By this time, the danger of a surprise late-season frost has usually passed, and the ground has begun to hold the warmth of the spring sun.
Cannas are true sun-worshippers. They will sit dormant and may even rot if they are placed in cold, soggy soil. For the best results, wait until the soil temperature consistently reaches 60°F. You can check this easily with a basic soil thermometer or by observing other plants in your neighborhood. If people are starting to put their tomato plants in the ground, it is generally safe to plant your cannas.
In the southern parts of Missouri, such as Springfield or Cape Girardeau, you might find that the soil warms up a week or two earlier than in the northern reaches of the state. If you are in the northernmost counties, waiting until the very end of May is often the smartest move to ensure the rhizomes sprout quickly and vigorously.
Key Takeaway: In Missouri, aim to plant cannas outdoors in mid-to-late May once the soil is 60°F and the danger of frost is gone.
Starting Cannas Indoors for an Early Start
Because Missouri has a finite growing season, many gardeners choose to start their cannas indoors. This "head start" allows the plants to develop roots and even a few inches of green growth before they ever touch the garden soil. This often leads to earlier blooms in the summer.
You can start your canna rhizomes in pots as early as late February or throughout March. This is roughly 6 to 8 weeks before the average last frost date. Follow these simple steps to start them inside:
- Choose the right container: Use a pot with drainage holes that is large enough to fit the rhizome comfortably without it touching the sides.
- Use quality potting soil: A standard, well-draining potting mix works best. Avoid using heavy garden soil in pots, as it can pack down too tightly.
- Planting depth: Place the rhizome about 2 to 4 inches deep with the "eyes" or growth points facing upward.
- Provide light and warmth: Place the pots in a sunny window or under grow lights. A warm spot, like the top of a refrigerator or near a vent, can help trigger the first sprouts.
Once the weather warms up in May, you can gradually move these potted plants outdoors. This process, called "hardening off," involves putting them outside for a few hours a day in a sheltered spot and slowly increasing their exposure to sun and wind over the course of a week.
Selecting the Right Spot in Your Missouri Garden
Success with cannas starts with choosing the right location. In Missouri, our summers are known for being hot and humid, which cannas absolutely love. However, they do have a few specific needs to look their best.
Sunlight Requirements
Cannas need full sun to produce their best foliage color and the most flowers. Aim for 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 producing fewer blooms. The intense afternoon sun in Missouri is perfectly fine for cannas as long as they stay hydrated.
Soil and Drainage
While cannas love water, they do not like to sit in stagnant, swampy puddles. They prefer soil that is rich in organic matter. If your Missouri soil is heavy clay—which is common in many parts of the state—you can improve it by mixing in some compost or well-rotted manure before planting. This helps the soil breathe and allows water to move through it more effectively.
Wind Protection
Because cannas have large, soft leaves, they can sometimes be torn by the strong thunderstorms that roll through Missouri in June and July. If possible, plant them in a location that offers some protection from the strongest winds, such as near a fence, a wall, or a cluster of sturdy shrubs.
How to Plant Canna Rhizomes: Step-by-Step
When you are ready to plant canna rhizomes, the process is straightforward. Getting the depth and spacing right will set your plants up for a successful season.
- Prepare the area: Loosen the soil to a depth of about 10 or 12 inches. This makes it easier for the new roots to spread out and find nutrients.
- Dig the hole: Dig a hole about 4 inches deep.
- Place the rhizome: Lay the rhizome horizontally in the hole. Look for the "eyes"—small bumps or points where the new growth will emerge. While it is best to point these upward, the plant will usually find its way to the surface even if it is placed sideways.
- Space them out: Cannas are vigorous growers. Give them plenty of room to breathe. Space standard varieties about 2 feet apart. If you are planting dwarf varieties, 12 to 18 inches is usually sufficient.
- Cover and press: Cover the rhizome with soil and press down firmly with your hands to remove any large air pockets.
- Water in: Give the area a good 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, but don't overwater until you see green shoots.
- Apply a thin layer of mulch to help hold in moisture and keep weeds at bay.
Watering and Feeding for Maximum Growth
Once your cannas have sprouted and the Missouri heat kicks in, their needs will change. These are "hungry" and "thirsty" plants that respond well to consistent care.
Watering Rules
In the peak of July and August, Missouri gardens can dry out quickly. Cannas prefer soil that is consistently moist. A deep soaking once or twice a week is better than a light sprinkle every day. If you are growing cannas in containers, they will likely need water every single day during a heatwave, as pots dry out much faster than the ground.
Fertilizing
To get those towering stems and large flowers, cannas benefit from a bit of extra food. You can use a balanced, all-purpose garden fertilizer once a month during the growing season. Follow the instructions on the product label for the correct amounts. If your soil is already very rich in compost, you may find that they grow perfectly well with even less fertilizer.
Dealing with Missouri Pests and Challenges
While cannas are generally very easy to grow, there are a few local visitors to keep an eye on. In Missouri, the most common issue is the canna leaf roller. These are small caterpillars that stitch the leaves shut before they can unfurl, creating a ragged, "Swiss cheese" look.
If you notice leaves that are stuck together or have rows of holes in them, you can usually manage the problem by simply unrolling the leaf and removing the caterpillar by hand. For larger plantings, a gentle spray recommended by your local garden center can help, but many gardeners find that keeping the plants healthy and vigorous allows them to outgrow any minor damage.
Japanese beetles may also take a nibble of the flowers in mid-summer. The best approach is to knock them into a bucket of soapy water in the early morning when they are less active.
Enjoying the Blooms and Foliage
Cannas typically begin blooming in Missouri in July and will continue right up until the first frost of autumn. To keep the plant looking its best and to encourage more flowers, you can practice "deadheading." This simply means snipping off the faded flower spikes once they have finished blooming.
When you deadhead, look closely at the stem. You will often see a new flower bud forming just below the old one. Be sure to cut only the spent bloom so you don't accidentally remove the next round of flowers.
Beyond the flowers, the foliage of many canna varieties is a highlight in itself. Varieties with variegated or striped leaves can look like stained glass when the sun shines through them from behind. We often recommend planting these where they can be "backlit" by the morning or evening sun for a spectacular effect.
End of Season: What to Do When Frost Hits
Because Missouri experiences freezing temperatures in the winter, your cannas will need some attention once the growing season ends. Usually, in October or November, a "killing frost" will arrive. This will turn the lush green leaves black or brown almost overnight.
Don't be alarmed—this is a natural part of the cycle. Once the foliage has turned brown, you have two choices:
Option 1: Treat Them as Annuals
If you don't want to deal with the storage process, you can simply leave the plants in the ground. They will not survive the winter, but you can enjoy them all summer and plant fresh rhizomes the following spring. This is a great, low-stress option for busy gardeners.
Option 2: Lift and Store
If you have a favorite variety that you want to keep, you can lift the rhizomes. Cut the stalks down to about 4 inches above the ground. Use a garden fork to gently lift the clump of roots out of the soil. Shake off the excess dirt and let them dry in a shaded, frost-free area (like a garage) for a few days.
Once they are dry to the touch, place them in a box filled with slightly damp peat moss or sawdust. Store the box in a cool, dark place where temperatures stay between 40°F and 50°F. A basement or a crawl space is usually perfect. Check on them once or twice during the winter to make sure they aren't shriveling up or getting mushy.
Conclusion
Growing cannas in Missouri is a rewarding way to add high-impact color and a touch of the tropics to your home. By waiting for the soil to warm in May and providing plenty of sun and water, you can create a stunning display that lasts for months. At Longfield Gardens, we believe that gardening should be a source of joy, and few plants provide as much "wow factor" for such a small investment of time as the canna.
- Wait for 60°F soil temperatures before planting outdoors.
- Give them a sunny spot with rich, well-draining soil.
- Keep them hydrated during the hot Missouri summer.
- Decide whether to lift them or replant fresh next year.
The next step is to choose your favorite colors and start planning your summer garden. Whether you plant them in a large border or a single patio pot, your cannas are sure to be a highlight of the season.
High-quality rhizomes and proper spring timing are the two most important ingredients for a beautiful canna display in any Missouri backyard.
FAQ
Can I leave my cannas in the ground during a Missouri winter?
In most parts of Missouri, cannas will not survive the winter if left in the ground because the soil freezes deep enough to damage the rhizomes. While a very mild winter in the far southern Bootheel might occasionally allow them to return, it is much safer to either lift and store them or plan on planting new ones each spring.
How long does it take for cannas to bloom after planting?
Once the weather is consistently warm, cannas are fast growers. You can typically expect to see the first flowers about 10 to 12 weeks after the rhizomes are planted in the ground. If you start them indoors in March, you may see blooms even earlier in the summer.
Why are my cannas growing leaves but no flowers?
The most common reason for a lack of flowers is a lack of sunlight. If cannas don't get at least 6 hours of direct sun, they may focus all their energy on foliage. Additionally, ensure you aren't using a fertilizer that is too high in nitrogen, which promotes green growth at the expense of blooms.
Should I soak canna rhizomes before planting them?
While not strictly necessary, soaking your rhizomes in a bucket of lukewarm water for a few hours before planting can help "wake them up" and encourage faster sprouting. However, if your soil is already very damp from spring rains, it is better to skip this step to avoid any risk of rot.