Table of Contents
- Introduction
- Temperature and Timing: The Most Common Hurdles
- Proper Planting Depth and Orientation
- Sunlight: The Fuel for Growth
- Water and Soil Drainage
- Nutrition and Soil Quality
- Space and Overcrowding
- Identifying Pests and Diseases
- Starting Rhizomes Indoors for a Head Start
- Varieties Matter: Growth Habits
- Summary of Growth Factors
- Conclusion
- FAQ
Introduction
There is nothing quite like the bold, tropical flair that canna lilies bring to a summer garden. With their oversized, paddle-shaped leaves and vibrant blooms in shades of red, orange, and yellow, they transform any backyard into an exotic retreat. We love how these plants provide both architectural height and a long season of color, making them a favorite for many home gardeners. At Longfield Gardens, we want to ensure you experience the full potential of these spectacular plants from the moment you tuck them into the ground.
If you find yourself wondering why your canna lilies are not growing as expected, you are not alone. Whether you are waiting for that first sprout to break through the soil or wondering why your plants have stalled at a certain height, the answers are usually found in a few basic requirements. This guide will walk you through the most common reasons for slow growth and provide practical steps to get your garden back on track. By understanding the simple needs of these tropical beauties, you can ensure a lush, thriving display all summer long.
Temperature and Timing: The Most Common Hurdles
Canna lilies are tropical plants at heart, which means they are highly sensitive to temperature. If your cannas are not growing, the most likely culprit is that the soil is simply too cold. These plants thrive in heat and will often sit dormant in the ground until they feel a consistent warmth that signals it is safe to wake up.
In many parts of the country, air temperatures might feel warm in early spring, but the soil takes much longer to catch up. If you plant your rhizomes when the ground is still chilly, they will stay in a state of "sleep" to protect themselves. We recommend waiting until the soil temperature reaches at least 60°F before expecting to see significant activity. If you planted early and haven't seen growth, do not worry; they are likely just waiting for a few consecutive weeks of warm weather.
Monitoring Soil Warmth
You do not need fancy equipment to check your garden conditions, though a simple soil thermometer can be a helpful tool. If the ground feels cold to the touch several inches down, it is likely too early for the rhizomes to begin pushing out new shoots. For gardeners in northern zones, this often means that cannas planted in May might not show their faces until well into June.
Avoiding Early Season Rot
While waiting for the soil to warm up, it is important to avoid overwatering. A dormant rhizome in cold, wet soil is at a high risk for rot. Until you see green growth above the soil line, keep the moisture levels moderate. The goal is to keep the soil from drying out completely without making it soggy. Once the plants are established and the weather is hot, they will appreciate much more frequent watering.
What to do next:
- Check your local soil temperature or wait until night temperatures are consistently above 50°F.
- Reduce watering until you see the first green shoots emerge.
- Use a layer of dark mulch or clear plastic over the planting area to help trap solar heat and warm the soil faster.
Proper Planting Depth and Orientation
Another frequent reason for my canna lilies not growing is the depth at which they were planted. It is a common mistake to think that deeper is better for protecting the plant, but for cannas, being buried too deep can cause significant delays.
If a rhizome is buried five or six inches deep, the young shoot has a long way to travel before it reaches the sunlight. This extra effort uses up the energy stored in the rhizome and can lead to stunted growth or a plant that never manages to break the surface at all. We suggest planting canna rhizomes only 2 to 3 inches deep. This shallow depth allows the sun to warm the soil around the rhizome and gives the new shoots a short, easy path to the air.
Identifying the "Eyes"
When you are planting, the orientation of the rhizome matters. Canna rhizomes have "eyes," which are the small, pointed buds where the new growth will emerge. Ideally, these eyes should be facing upward or sideways. If a rhizome is planted with the eyes pointing straight down, the plant has to grow in a U-turn shape to find the surface. This adds time and stress to the initial growth phase.
Soil Preparation for Easy Sprouting
If your soil is very heavy or compacted, it can act like a physical barrier for the new shoots. Loosening the soil to a depth of about 6 inches before planting ensures that the delicate new growth can push through easily. Mixing in a little bit of compost can also improve the soil structure, making it easier for the rhizome to establish a strong root system.
Key Takeaway: Planting canna rhizomes 2 to 3 inches deep with the eyes facing upward is the fastest way to see green growth in your garden.
Sunlight: The Fuel for Growth
Canna lilies are sun worshippers. If your plants have sprouted but seem to be standing still, take a look at how much direct light they receive throughout the day. To grow at their best and produce those iconic flowers, cannas need at least 6 to 8 hours of direct sunlight every day.
In shady spots, canna lilies will grow much slower. They may produce leaves, but the foliage will often be thinner and less vibrant than plants grown in full sun. Furthermore, a lack of sunlight is the leading cause of cannas that produce plenty of leaves but never actually bloom. If your garden has become more shaded over the years due to growing trees or new structures, your cannas may be struggling to get the "fuel" they need to perform.
Finding the Right Spot
If you suspect your cannas aren't growing because of shade, moving them to a sunnier location is often the best fix. Because they grow from rhizomes, they are relatively easy to dig up and relocate, even early in the growing season. Choose a spot with southern exposure where the sun hits the ground for the majority of the afternoon.
Growth in Partial Shade
While full sun is ideal, some varieties can tolerate partial shade, especially in very hot climates where the afternoon sun is intense. However, even in these conditions, "partial shade" should still mean at least 4 to 5 hours of direct light. Anything less will result in a plant that feels lackluster and slow to develop.
Water and Soil Drainage
Finding the right balance of moisture is a key part of successful canna gardening. These plants are unique because they love water—many can even be grown in the shallow edges of ponds—but they are still susceptible to rot if the soil is stagnant and lacks oxygen.
If your canna lilies are not growing, the soil might be either too dry or too poorly drained. In the early stages of growth, the rhizome needs consistent moisture to "prime" its internal systems and start sending out roots. If the soil dries out completely, the plant may go back into a protective dormancy.
The Importance of Drainage
While cannas like to stay moist, the water must be able to move through the soil. Heavy clay soil that stays waterlogged for days after a rain can drown the rhizome. This leads to rot, which is often identified by a mushy texture and a bad odor if you were to dig the rhizome up. We recommend planting in soil that has been amended with organic matter to ensure it holds onto moisture without becoming a muddy mess.
Watering During Growth Spurts
Once your cannas are about a foot tall, their water needs will increase dramatically. During the heat of mid-summer, a large canna lily can transpire a significant amount of water through its wide leaves. If they don't get enough water during this stage, their growth will stall. You might notice the edges of the leaves turning brown or "tearing," which is a clear sign the plant is thirsty.
What to do next:
- Stick your finger two inches into the soil; if it feels dry, it is time to water.
- Apply a 2-inch layer of mulch around the base of the plants to help maintain consistent moisture levels.
- If your soil is heavy clay, consider growing cannas in raised beds or large containers where you can control the drainage.
Nutrition and Soil Quality
Canna lilies are "heavy feeders." This means they require more nutrients than the average garden perennial to reach their impressive heights. If your cannas have sprouted but remain small and pale, they might be hungry for more nitrogen and phosphorus.
In many home gardens, the soil is sufficient for basic growth but lacks the "extra" power needed for tropical plants. If you haven't added any fertilizer or compost to your garden bed in a few years, your cannas may be struggling to find the minerals they need to build those large leaves and thick stems.
Choosing the Right Fertilizer
We suggest using a balanced, all-purpose fertilizer or one specifically formulated for flowering bulbs and perennials. Nitrogen helps with the green, leafy growth, while phosphorus supports strong root development and flower production. Following the instructions on the product label is essential, as over-fertilizing can sometimes do more harm than good. A common schedule is to fertilize once at planting and then again every 4 to 6 weeks during the peak growing season.
The Role of Organic Matter
Adding compost or well-rotted manure to your planting site is one of the best ways to provide long-term nutrition. Organic matter doesn't just provide food; it also improves the soil's ability to hold onto water and allows air to reach the roots. A healthy soil environment is the foundation for a fast-growing canna lily.
Space and Overcrowding
Canna lilies are vigorous growers that spread via their underground rhizomes. Over time, a single planted rhizome can turn into a large, dense clump. While this sounds like a good thing, it can eventually lead to overcrowding. When cannas are packed too tightly together, they begin to compete for the same limited resources: water, sunlight, and nutrients.
If you have an established patch of cannas that was spectacular last year but is barely growing this year, overcrowding is the likely cause. The plants are essentially "choking" each other out. This competition leads to smaller leaves, thinner stems, and fewer flowers.
How to Divide Canna Lilies
To keep your cannas growing vigorously, we recommend dividing the clumps every 2 to 3 years. This is best done in the spring before the plants have put on much growth. Simply dig up the entire clump and use a clean, sharp spade or garden knife to cut the rhizomes into smaller sections. Each section should have at least 2 or 3 healthy "eyes." Replanting these divisions with plenty of space—about 12 to 18 inches apart—will give each plant the room it needs to thrive.
Airflow and Health
Spacing isn't just about food and light; it's also about airflow. When plants are too crowded, air cannot circulate between the leaves. This creates a humid environment that invites pests and fungal diseases, both of which can slow down or stop growth entirely. Proper spacing ensures the foliage stays dry and the plants stay healthy.
Key Takeaway: Dividing your cannas every few years revitalizes the plants and ensures they have the space and resources to reach their full size.
Identifying Pests and Diseases
Sometimes, canna lilies are not growing because they are under attack from "hidden" garden visitors. While cannas are generally robust, there are a few specific pests and diseases that can cause them to stall.
Canna Leaf Rollers
The most common pest for these plants is the canna leaf roller. This is the caterpillar stage of a small butterfly. These pests stitch the edges of the leaves together before they can fully unfurl. If you see a leaf that looks like it is stuck in a rolled-up position, or if you notice a row of holes when a leaf finally opens, you likely have leaf rollers. This damage prevents the leaf from capturing sunlight, which stunts the plant’s growth.
Japanese Beetles
In some regions, Japanese beetles can be a significant problem in mid-summer. They eat the tissue between the leaf veins, leaving behind a "skeletonized" leaf. While a few beetles won't stop a plant from growing, a heavy infestation can weaken the plant and cause it to stop producing new growth as it tries to recover from the damage.
Fungal and Viral Issues
- Rust: This appears as orange or brownish powdery spots on the undersides of leaves. It thrives in humid conditions and can cause leaves to yellow and die prematurely.
- Canna Virus: If your plants have yellow streaks or mottled patterns on the leaves and they seem stunted despite good care, they may have a virus. Unfortunately, there is no cure for plant viruses. If you suspect a virus, it is best to remove the affected plant to prevent it from spreading to others.
What to do next:
- Inspect the centers of new, unrolled leaves for any webbing or caterpillars.
- Remove damaged foliage to keep the plant looking clean and to reduce the habitat for pests.
- For major pest issues, consult your local extension office for safe and effective treatment options in your area.
Starting Rhizomes Indoors for a Head Start
If you live in a region with a short growing season (Zones 3 through 6), you might find that your cannas "never seem to grow" simply because they run out of time. By the time the soil is warm enough for them to sprout, the summer is already half over.
One of the best tricks we recommend at Longfield Gardens is starting your rhizomes indoors about 4 to 6 weeks before the last frost. This gives the plants a "head start" so that when you move them outside, they are already several inches tall and ready to take advantage of the summer sun.
How to Start Indoors
- Fill 8-inch or 10-inch pots with a high-quality, well-draining potting mix.
- Plant the rhizomes 2 inches deep.
- Place the pots in a warm, sunny spot, like a south-facing window or under grow lights.
- Keep the soil lightly moist but not wet.
- Once the danger of frost has passed and the soil outside is warm, transplant them into your garden.
This simple step can mean the difference between a plant that barely reaches three feet tall and one that towers over the garden with a full display of blooms.
Varieties Matter: Growth Habits
It is also worth noting that not all canna lilies are designed to grow to the same height. If you feel your cannas are not growing "tall enough," you might simply have a dwarf variety. Canna lilies come in a wide range of sizes, from compact versions that stay under 2 feet to giants that can reach 6 or 8 feet in a single season.
Before worrying about the growth rate, check the variety you planted. Dwarf cannas are excellent for containers and the front of garden borders, but they will never reach the towering heights of a variety like Canna Tall Tropicanna. Understanding the genetic potential of your specific plant will help you set realistic expectations for your garden.
Foliage-Focused vs. Flower-Focused
Some cannas are bred specifically for their spectacular foliage rather than their flowers. Varieties with striped or multicolored leaves may grow a bit slower than the standard green-leaved types because they have less chlorophyll to process sunlight. If you are growing a variety with highly variegated leaves, it is normal for it to take a little more time to establish itself.
Summary of Growth Factors
Getting your canna lilies to grow successfully often comes down to matching their tropical origins with your local garden conditions. They aren't difficult plants, but they are very clear about what they need to succeed.
- Heat: Soil should be 60°F or warmer for active growth.
- Depth: 2–3 inches is the sweet spot for planting.
- Sun: 6+ hours of direct light is non-negotiable for best results.
- Water: Keep them moist, especially in the heat of summer.
- Food: Use compost or fertilizer to support their fast-paced growth.
"A thriving canna lily is a reflection of its environment. When you provide heat, light, and water, these plants reward you with a lush, tropical energy that few other perennials can match."
Conclusion
Seeing your canna lilies not growing can be a bit puzzling, but it is almost always a sign that the plant is waiting for one of its basic needs to be met. By ensuring your rhizomes have enough warmth, plenty of sunlight, and the right planting depth, you can unlock their potential for a stunning garden display. Gardening is a rewarding journey of observation and small adjustments, and canna lilies are incredibly resilient once they find their groove.
- Wait for warm soil before expecting rapid growth.
- Check that your plants aren't buried too deep.
- Provide plenty of water and sunshine during the summer months.
- Divide older clumps to keep the plants vigorous.
We invite you to explore the different colors and textures available at Longfield Gardens to find the perfect match for your landscape. With just a little bit of patience and care, you’ll be enjoying those tropical blooms all season long.
FAQ
Why are my canna lilies taking so long to sprout?
Cannas are tropical plants that require warm soil to begin growing. If the ground temperature is below 60°F, the rhizome will likely remain dormant. It is common for cannas to take three to four weeks to show their first shoots, especially in northern climates where the soil warms up slowly in late spring.
Can I grow canna lilies in pots if they aren't growing well in the ground?
Yes, growing cannas in containers is a great way to manage their environment. Pots warm up much faster than the ground, which can lead to earlier sprouting. Additionally, containers allow you to easily control the soil quality or move the plant into the sunniest spots of your yard or patio. For more container tips, see How to Grow Canna Bulbs in Containers.
Do I need to dig up my canna lilies every year?
This depends on your USDA hardiness zone. If you live in Zone 8 or warmer, canna lilies can usually stay in the ground year-round with a thick layer of mulch for protection. In colder zones (Zone 7 and below), the rhizomes will freeze and die if left outside, so they must be lifted and stored in a frost-free place for the winter. You can check your growing region with the Hardiness Zone Map.
How do I know if my canna rhizomes are dead?
A healthy canna rhizome should feel firm and heavy, similar to a fresh ginger root. If you dig up a rhizome and it feels mushy, hollow, or lightweight, it has likely rotted or dried out and will not grow. If it is firm but has no green growth, it may simply be dormant and waiting for more heat.
Want more help with canna timing, spacing, and planting?
If your plants are still slow to emerge, it can help to review How Deep to Plant Canna Lily Bulbs in the Ground and How Far Apart Do You Plant Canna Bulbs?. For order-related questions, visit our Shipping Information page or learn more About Us.