Table of Contents
- Introduction
- The Secret to Speed: Understanding the Tropical Clock
- Start Rhizomes Indoors for a Head Start
- Wait for the 60-Degree Soil Mark
- Prioritize Sunlight and Location
- Water Correctly for Maximum Speed
- Feeding for Foliage and Flowers
- Choose the Right Varieties for Your Goals
- Troubleshooting Slow Growth (Positively!)
- The Advantage of Container Growing
- Maintenance for Continued Growth
- Conclusion
- FAQ
Introduction
There is nothing quite like the feeling of watching a tropical paradise take shape in your own backyard. Canna lilies are the champions of this transformation, growing from humble rhizomes into towering, vibrant focal points in just a single season. At Longfield Gardens, we enjoy seeing how these heat-loving plants bring a sense of exotic luxury to sunny borders and patio containers across the country.
Many gardeners find themselves checking the soil daily, eager to see those first green spears pierce through the earth. While cannas are naturally vigorous, there are several simple and effective ways to help them reach their full potential even sooner. This guide focuses on practical steps you can take to accelerate their growth, from giving them a head start indoors to providing the specific nutrients they crave.
By understanding what these tropical beauties need most, you can enjoy a garden filled with lush foliage and brilliant blooms weeks earlier than usual. Whether you are a beginner or a seasoned pro, these tips will help you maximize every warm day of the summer season. Our goal is to ensure your gardening experience is rewarding, successful, and entirely stress-free.
The Secret to Speed: Understanding the Tropical Clock
To make cannas grow faster, we first have to think like a tropical plant. Cannas are native to warm, humid regions where the sun is intense and the growing season never truly ends. When we plant them in our US gardens, they are essentially waiting for the environment to mimic those tropical conditions.
The most important factor in the speed of canna growth is heat. While other spring-planted bulbs might be okay with cool spring rains, cannas prefer to stay dormant until the world around them warms up. If you plant them too early in cold, damp soil, they will simply wait. This waiting period is often what makes them feel "slow."
The good news is that once the conditions are right, cannas are some of the fastest-growing plants in the landscape. They can grow several inches in a single week during the height of summer. Our strategy for speeding them up focuses on two things: reducing the "waiting time" and maximizing their "sprinting time" once they start growing.
Key Takeaway Canna lilies are heat-activated. The faster you can provide them with consistent warmth, the sooner they will transition from dormant rhizomes into active, growing plants.
Start Rhizomes Indoors for a Head Start
The most effective way to see blooms earlier in the summer is to start your cannas indoors before the last frost. This moves the "waiting phase" into your house or a warm garage, allowing the plants to develop roots and shoots while the outdoor soil is still too cold.
Choosing Your Timing
We suggest starting your canna rhizomes indoors about 4 to 6 weeks before your average last frost date. This gives the plant enough time to establish a strong root system and a few inches of green growth without becoming so large that it is difficult to move outside later.
The Potting Process
Select a pot that is at least 8 to 10 inches in diameter with good drainage holes. Use a high-quality, well-draining potting mix. Place the rhizome horizontally in the soil, about 2 to 3 inches deep. You may notice small bumps or points on the rhizome; these are the "eyes." If you see them, point them upward, but don't worry if you can't tell which side is which—the plant will naturally find its way toward the light.
Warmth and Light Requirements
For the fastest results indoors, place your pots in a warm spot. A room that stays consistently between 65°F and 75°F is ideal. Some gardeners use a seed-starting heat mat under their pots to provide gentle bottom heat, which mimics the warm tropical soil cannas love.
Once the first green spikes appear, the plants need plenty of light. A bright, south-facing window is a great choice. If you don't have enough natural light, a simple LED grow light kept a few inches above the foliage will keep the plants from becoming "leggy" or weak.
Transitioning to the Garden
Before moving your indoor-started cannas directly into the full sun, they need to be "hardened off." This is a simple process of getting them used to the outdoor environment.
- Day 1-2: Place the pots in a shady, sheltered spot for two hours, then bring them back inside.
- Day 3-4: Increase the time to four hours and move them into dappled sunlight.
- Day 5-7: Leave them outside all day in a sunny spot, bringing them in only if a frost is predicted.
What to Do Next
- Find your local last frost date using a regional calendar.
- Gather 1-gallon pots and fresh potting soil.
- Start your rhizomes 4-6 weeks before that frost date.
- Keep the soil lightly moist but never soggy while they are indoors.
Wait for the 60-Degree Soil Mark
If you prefer to plant your canna lilies directly into the garden, timing is everything. One of the most common reasons cannas grow slowly is that they were planted in soil that was too cold. We recommend waiting until the soil temperature is consistently 60°F or higher.
For most of us, this is usually about the same time you would feel comfortable planting tomatoes or peppers. If you plant earlier than this, the rhizome may sit in the ground for weeks without doing anything. In some cases, cold and wet soil can even lead to rot before the plant has a chance to sprout.
Measuring Soil Temperature
You don't need expensive tools to get this right. A simple soil thermometer inserted about 3 inches deep will give you an accurate reading. Check the temperature in the morning for three days in a row. If it stays at or above 60°F, your cannas will "wake up" almost immediately upon planting, leading to much faster visible growth.
The Benefit of Warm Soil
When the soil is warm, the rhizome can immediately begin producing the fine feeder roots it needs to take up water and nutrients. This rapid root development provides the energy needed to push that first green spike through the soil surface. A canna planted in 65°F soil will often outpace a canna planted three weeks earlier in 45°F soil.
Prioritize Sunlight and Location
Cannas are essentially solar-powered. To make them grow as fast as possible, they need to be in a location where they can soak up the sun's energy for the majority of the day.
The Six-Hour Rule
At a minimum, cannas need six hours of direct, unfiltered sunlight. However, if you want them to reach their maximum height and bloom as early as possible, eight to ten hours is even better. In northern regions with shorter days, every extra hour of sun makes a significant difference in growth speed.
Utilizing "Heat Islands"
You can use the layout of your home and garden to give your cannas a little extra warmth. Planting cannas near a brick wall, a stone patio, or a dark-colored fence can create a "microclimate." These surfaces absorb heat during the day and radiate it back toward the plants at night. This keeps the ambient temperature around the foliage higher, which can noticeably speed up growth in late spring and early summer.
Protection from Wind
While cannas love the sun, they are not big fans of strong, drying winds. Their large, paddle-like leaves can act like sails. If they are constantly whipped by the wind, the plant spends energy repairing damaged leaf tissue rather than growing taller. Choosing a spot that is sunny but sheltered by a hedge, a building, or other tall perennials will help the plant focus all its energy on rapid upward growth.
Water Correctly for Maximum Speed
Because canna lilies grow so much mass in such a short amount of time, they require a lot of water. In fact, cannas are one of the few garden plants that can actually thrive in "boggy" conditions or at the edge of a pond.
The "Deep Soak" Method
To encourage fast growth, avoid light daily sprinkling. Instead, give your cannas a deep soak once or twice a week (or more often in extreme heat). This encourages the roots to grow deep into the soil, creating a stable and efficient system for absorbing nutrients.
Adjusting for Soil Type
- Sandy Soil: Water drains through sand very quickly. If your soil is sandy, you may need to water every other day during the summer to keep the growth rate high.
- Clay Soil: Clay holds onto water for a long time. While cannas like moisture, you should still check the top inch of soil. If it feels muddy, wait a day before watering again.
- Containers: Plants in pots dry out much faster than those in the ground. During the hottest weeks of July and August, container-grown cannas may need a thorough watering every single day.
The Role of Mulch
Applying a 2-to-3-inch layer of organic mulch, such as shredded bark or compost, around the base of your cannas is a great way to speed up growth. Mulch does two important things: it keeps the soil moisture consistent and it helps maintain a steady soil temperature. By preventing the soil from drying out and "crusting" on top, you ensure the plant never has to slow down its growth due to water stress.
Key Takeaway Think of water as the fuel for your canna’s growth. If the soil stays consistently moist (like a wrung-out sponge), the plant can maintain its "green rush" without interruption.
Feeding for Foliage and Flowers
Cannas are known in the gardening world as "heavy feeders." This means they use up soil nutrients very quickly to support their massive leaves and frequent flower spikes. If you want them to grow faster, you need to provide a steady supply of nutrients.
At Planting Time
When you first put your rhizomes in the ground (or in pots), we recommend mixing some compost or a balanced, slow-release fertilizer into the soil. This provides a "safety net" of nutrition that will be available as soon as the first roots emerge.
During the Growing Season
Once the plants are about 12 inches tall, they enter their most aggressive growth phase. This is the time to start a regular feeding schedule.
- High-Nitrogen Fertilizer: Nitrogen is the nutrient responsible for green, leafy growth. Using a fertilizer with a slightly higher first number (the "N" in N-P-K) can help the stalks shoot up quickly.
- Balanced Fertilizer: A standard 10-10-10 fertilizer works well for general health.
- Liquid vs. Granular: Liquid fertilizers act more quickly because the roots can absorb them immediately. If you want a quick boost, a water-soluble fertilizer applied every two weeks is very effective. Granular fertilizers last longer but take a bit more time to break down.
Knowing When to Stop
While feeding helps speed up growth, you should stop fertilizing in late summer, usually about four to six weeks before your first expected frost. This allows the plant to naturally begin slowing down and preparing for its dormant period, rather than being forced into a flush of tender new growth that might be damaged by the first cold snap.
Choose the Right Varieties for Your Goals
Not all canna lilies grow at the same speed or reach the same ultimate height. If your main goal is to see a tall, lush screen as quickly as possible, variety selection matters.
Green vs. Variegated Foliage
In our trial gardens, we often observe that cannas with solid green leaves tend to grow slightly faster than those with variegated (multi-colored) leaves. This is because green leaves contain more chlorophyll, which allows the plant to process sunlight into energy more efficiently.
- Fast Growers: Varieties like 'Musifolia' (which can reach 8 feet or more) or classic green-leaved types are built for speed.
- Dramatic but Slower: Beautiful varieties like Canna Tall Tropicanna Black or those with white-and-green striped leaves may grow a little more slowly because they have less green surface area to capture energy. They are still vigorous, but they may take a few extra days to reach their peak height.
Tall vs. Dwarf Varieties
If you want height quickly, choose "standard" or "tall" varieties. These are genetically programmed to reach 4 to 6 feet (or more). Medium Cannas and dwarf varieties, which usually top out at 2 or 3 feet, will still grow quickly, but they will reach their "finished" look much sooner because they have less distance to cover.
Troubleshooting Slow Growth (Positively!)
Sometimes, despite our best efforts, a canna lily might seem like it's taking a break. Usually, this is the plant's way of telling you it needs one small adjustment.
Checking for "Sleepy" Rhizomes
If it has been three weeks and you don't see a sprout, don't worry. Sometimes a rhizome is just a bit deeper in dormancy than its neighbors. The best "fix" here is a simple increase in temperature. If the plant is in a pot, move it to a warmer spot. If it's in the ground, ensure you haven't piled too much mulch directly over the planting spot, which might be keeping the sun's rays from warming the soil.
Addressing "Leggy" Growth
If your canna is growing tall but looks thin and weak, it is likely searching for more light. The solution is easy: move the pot to a sunnier location or trim back any overhanging branches from nearby shrubs that might be casting a shadow. Once the plant gets enough sun, the stems will thicken up and the growth will become more robust.
Reviving "Hungry" Plants
If the leaves look pale green or yellow instead of a deep, healthy green, the plant is likely asking for a snack. A quick application of a balanced liquid fertilizer often results in a "greening up" of the foliage within just a few days.
What to Do Next
- Observe your plants for 5 minutes each week.
- Look for vibrant color and strong stems.
- If growth seems stalled, check soil moisture and sun exposure first.
- Add a liquid feed if the foliage looks pale.
The Advantage of Container Growing
Growing cannas in containers is one of the easiest ways to control their growth speed. Because the soil in a pot is above the ground, it warms up much faster in the spring sun than the earth does. This "top-down" heating can shave a week or more off the sprouting time.
Pot Selection
Cannas have powerful roots and expanding rhizomes. We recommend using heavy-duty plastic or resin pots. Terracotta or ceramic pots are beautiful, but a fast-growing canna rhizome can actually crack them from the inside as it grows! A 12-to-15-inch pot is a great starting size for a single rhizome.
Mobility
The "speed secret" of containers is mobility. In the early spring, you can move your pots into the sunniest, warmest part of your driveway or patio during the day and tuck them into a garage at night if the temperature drops. This "chasing the sun" strategy ensures the plant stays in its ideal growth zone for as many hours as possible.
Maintenance for Continued Growth
Once your canna has reached its full height and started blooming, you can keep the momentum going with two simple tasks: deadheading and thinning.
Deadheading for More Flowers
As individual flowers fade, they often form a bumpy green seed pod. If the plant spends its energy making seeds, it will slow down its flower production. By snipping off the faded blooms (just above the next bud), you signal to the plant that it should keep producing more flowers.
Thinning the Clump
Cannas spread by creating new rhizomes underground. Over a few years, a single planting can become very crowded. When a clump is too dense, the individual stalks have to compete for water and nutrients, which can slow them down. Every few years, digging up and dividing your cannas in the spring will ensure that each piece has enough space to grow at maximum speed.
Conclusion
Creating a tropical-inspired garden doesn't have to be a long or difficult process. By focusing on the basics—warmth, water, sun, and food—you can make your canna lilies grow faster and more vigorously than ever before. Whether you choose to start them indoors for a head start or simply wait for the perfect 60-degree soil, the result will be a stunning display of color and texture that lasts all summer long.
At Longfield Gardens, we want you to feel confident and excited every time you step into your garden. Gardening is a journey of discovery, and canna lilies are some of the most rewarding companions you can choose for that journey. We stand behind the quality of our rhizomes and are here to support you as you grow your most beautiful garden yet.
- Warmth is Key: Prioritize soil and air temperatures above 60°F.
- Sun and Water: Give them 6+ hours of sun and consistent, deep moisture.
- Feed Regularly: Use a balanced fertilizer to support their rapid growth.
- Start Early: Use pots indoors to gain an extra month of beauty.
Final Thought The most successful gardens are built on simple steps and a little bit of patience. Once the heat of summer hits, your canna lilies will reward your care with a breathtaking show of tropical elegance.
FAQ
How long does it take for canna lilies to sprout?
In ideal conditions with warm soil (above 60°F), you can expect to see green spikes emerging within 2 to 3 weeks. If the weather is cool or the rhizomes were planted in cold soil, it may take up to 4 or 5 weeks for them to wake up.
What is the best fertilizer to make cannas grow taller?
A fertilizer with a higher nitrogen content (the first number on the package) is best for encouraging tall stalks and large leaves. Many gardeners find success using a balanced slow-release fertilizer at planting time, followed by a liquid "booster" every two weeks during the peak of summer.
Can canna lilies grow in the shade?
While cannas can survive in partial shade, they will grow much more slowly and produce fewer flowers. For the fastest growth and most vibrant colors, they really need at least six hours of direct, unfiltered sunlight each day.
Do canna lilies need a big pot to grow fast?
Yes, cannas need space for their roots to expand. A pot that is too small will dry out too quickly and restrict the growth of new rhizomes, which can stunt the plant. We recommend a container that holds at least 3 to 5 gallons of soil for a single large rhizome.