Learning how to store canna bulbs is a crucial skill for any gardener in a climate with frosty winters. Properly storing canna bulbs through the winter ensures they return healthy and ready to bloom next spring. These tropical plants won’t survive freezing temperatures in the ground, but with the right technique, you can preserve their rhizomes for years of vibrant summer color.
This guide provides a clear, step-by-step process. We’ll cover everything from timing your dig to creating the perfect storage environment. Follow these instructions to keep your canna bulbs dormant and protected until it’s time to plant again.
How To Store Canna Bulbs
The core process of storing canna bulbs involves digging them up, cleaning and drying them, and placing them in a cool, dark place. While it sounds straightforward, each step has important details that influence your success. Rushing or skipping a step can lead to rot or desiccation, resulting in lost plants.
Think of it as tucking your plants in for a long winter’s nap. The goal is to mimic the dry season of their native habitat, encouraging dormancy without allowing the rhizomes to dry out completely or succumb to mold. With careful attention, your stored bulbs will be full of energy for the next growing season.
When To Dig Up Canna Bulbs
Timing is the first critical factor. Digging too early sacrifices potential growth, while digging too late risks frost damage. The key signal is the first frost of autumn. After a light frost, the canna’s foliage will blacken and die back. This is your cue to start the storage process.
If you live in an area with mild winters and no frost, you can leave cannas in the ground. However, many gardeners in these regions still choose to dig and divide them every few years to manage their size and vigor. For most, the post-frost timeline is essential.
Signs Your Cannas Are Ready For Storage
Look for these visual indicators in your garden:
- The foliage has turned brown or black following a frost.
- The plant has stopped flowering and growth has halted.
- The weather forecast predicts a hard freeze that will penetrate the soil.
Tools And Materials You Will Need
Gathering your supplies before you start makes the job smoother. You likely have most of these items already in your garden shed or home.
- A garden fork or spade for digging.
- Pruning shears or a sharp knife.
- Gardening gloves.
- A hose or bucket of water for rinsing.
- Newspaper or cardboard for drying.
- Peat moss, vermiculite, or wood shavings for packing material.
- Paper bags, cardboard boxes, or mesh bags for storage containers.
- A permanent marker for labeling.
Step-By-Step Guide To Preparing Canna Bulbs
Now, let’s walk through the preparation process. Taking your time here is the foundation of successful storage.
Step 1: Carefully Digging Up The Rhizomes
Start by cutting back the dead foliage to about 2-3 inches above the soil line. This makes handling easier. Using your garden fork, insert it into the soil about a foot away from the main stalk to avoid spearing the bulbs. Gently loosen the soil in a circle around the plant.
Lift the entire clump out of the ground. Shake off excess soil, but don’t worry about getting it perfectly clean yet. Be gentle, as the rhizomes can be brittle. If the clump is very large, you may need to divide it now or later during cleaning.
Step 2: Cleaning And Trimming
Once the clump is out, use your hands or a gentle stream from a hose to remove the bulk of the soil. Do not scrub the rhizomes, as this can damage the outer skin. After rinsing, inspect each bulb. Use your pruning shears to cut away any rotten, mushy, or damaged sections. Healthy tissue is firm.
Trim the remaining stalk down to about an inch. Also, trim any long, stringy roots, leaving about an inch of root attached. This helps prevent excess moisture loss. If you choose to divide large clumps, ensure each division has at least one eye (a pink or white bud) and a portion of the thick rhizome.
Step 3: The Crucial Drying Period
This step cannot be rushed. Proper drying prevents fungal and bacterial rot during storage. Lay the cleaned rhizomes in a single layer on newspaper or cardboard in a well-ventilated, shaded spot. A garage, garden shed, or covered porch is ideal.
Allow them to cure for one to three days. The outer skin should feel dry to the touch, and the cut ends from trimming should callous over. Do not place them in direct sunlight or use artificial heat to speed this process, as it can cause them to shrivel.
Choosing The Right Storage Medium
The packing material you use insulates the bulbs and maintains a slight, consistent level of moisture. The goal is to prevent them from drying out completely while absorbing any excess humidity that could cause rot.
- Peat Moss: A popular choice. It’s slightly acidic and retains moisture well. Ensure it is barely damp, not wet.
- Vermiculite: Excellent for aeration and moisture retention. It’s sterile and helps prevent disease.
- Wood Shavings or Sawdust: Use only untreated, non-aromatic wood (like pine). Avoid cedar, as its oils can be harmful to the bulbs.
- Coco Coir: A sustainable alternative to peat moss with similar properties.
- Dry Sand: Can be used, but it is very heavy and may dry out the rhizomes too much if not monitored.
Before packing, lightly dust the bulbs with a fungicide powder or sulfur dust. This is an optional but recommended step for extra protection against mold, especially in humid climates.
Packing And Storing Your Bulbs
Now it’s time to pack your dried and treated canna bulbs for their long rest. Choose a breathable container like a cardboard box, a wooden crate, or a paper bag. Plastic bags or airtight containers trap moisture and are a leading cause of storage rot.
Place a 2-inch layer of your chosen packing material in the bottom of the container. Arrange the bulbs in a single layer, ensuring they are not touching eachother. Cover them completely with more packing material. You can add additional layers, separating each with packing material.
Finally, label the container clearly with the variety and color of the canna. This seems simple, but you’ll thank yourself come spring. Place the container in its final storage location.
Ideal Storage Conditions
Finding the right spot is the final piece of the puzzle. The environment needs to be cool, dark, and have stable humidity.
- Temperature: Aim for a consistent temperature between 45°F and 55°F (7°C to 13°C). A basement, unheated garage, or cool crawl space often works well. Avoid areas that freeze or get too warm.
- Darkness: Light can trigger premature growth. Ensure the storage area is dark or that your container is opaque.
- Humidity: The air should be moderately dry. Very damp conditions promote mold, while very dry air can desiccate the rhizomes. Your packing medium helps regulate this.
Winter Storage Maintenance
Don’t just forget about your bulbs until spring. A quick monthly check can save your stock. Open the container and gently inspect a few bulbs. Look for signs of shriveling (too dry) or soft spots and mold (too moist).
If bulbs are shriveling, lightly mist the packing material with water—never the bulbs directly. If you see mold, remove the affected bulb immediately to prevent spread. Increase ventilation and consider replacing the packing material if it feels damp. Good air circulation in the storage room itself is also beneficial.
Common Storage Mistakes To Avoid
Being aware of these common errors will greatly increase your chances of success.
- Storing While Wet: This is the number one cause of rot. Ensure bulbs are fully cured.
- Using Plastic Bags: Creates a humid, stagnant environment perfect for fungus.
- Storing in a Warm Location: Heat can break dormancy, causing weak, spindly growth in storage.
- Letting Them Freeze: Frozen rhizomes turn to mush when thawed.
- Packing Too Densely: Bulbs touching can spread rot quickly.
- Forgetting to Label: Makes spring planting a guessing game.
Preparing Stored Bulbs For Spring Planting
About a month before your last expected spring frost, it’s time to wake up your cannas. Bring the container out of storage and unpack the bulbs. Discard any that are soft, rotten, or overly shriveled.
To encourage growth, you can pot them up in a loose potting mix and place them in a warm, sunny window indoors. This gives them a head start. Alternatively, you can plant them directly in the ground after all danger of frost has passed and the soil has warmed. Pre-sprouted bulbs will flower earlier in the summer.
Troubleshooting Stored Canna Bulbs
Even with the best care, issues can arise. Here’s how to handle common problems.
Bulbs Are Shriveled and Dry
This indicates the storage environment was too dry. You can try to rehydrate them by soaking the bulbs in lukewarm water for an hour or two before planting. Not all will recover, but some may still have life in them.
Bulbs Are Soft or Mushy
Softness is a sign of rot, often from excess moisture or improper drying. Check the bulb by cutting into it. If the center is brown or black and mushy, it is not salvageable. If only a small section is affected, you can cut it away, dust the cut with fungicide, and try to plant the remaining firm portion.
Mold on Bulbs or Packing Material
Surface mold can often be brushed off if the bulb underneath is still firm. Increase air flow in your storage area and ensure your packing medium is only slightly damp, not wet. Re-pack in fresh, dry material.
Bulbs Sprouted in Storage
If they begin to grow pale, weak shoots, the storage area is too warm and light. You have two options: pot them up and grow them as houseplants under a light, or carefully break off the fragile growth and move the bulbs to a cooler, darker location until planting time. The new growth is often too weak to survive.
FAQ About Storing Canna Bulbs
Here are answers to some frequently asked questions about canna bulb storage.
Can You Leave Canna Bulbs in the Ground Over Winter?
Only in USDA hardiness zones 8 through 11, where the ground does not freeze. In colder zones, the rhizomes will freeze and die. Even in warmer zones, a thick layer of mulch is recommended for protection during unexpected cold snaps.
How Long Can You Store Canna Bulbs?
Properly stored, canna rhizomes can remain viable for several months, from autumn until late spring. They are not typically stored for multiple years, as they are best divided and replanted annually to maintain health and vigor.
Do Canna Bulbs Need to Be Divided Before Storage?
It is not strictly necessary, but it is often easier to manage. Large clumps are heavy and harder to clean, dry, and pack effectively. Dividing them before storage allows you to inspect each piece and saves space. You can also divide them in spring before planting.
What is the Best Temperature to Store Canna Bulbs?
The ideal temperature range is between 45°F and 55°F (7°C to 13°C). This range is cool enough to maintain dormancy but not so cold as to cause freezing damage. Consistency is more important than hitting an exact number.
Can You Store Canna Bulbs in a Refrigerator?
It is not recommended. Refrigerators are designed to remove moisture, which can desiccate the bulbs. Furthermore, the humidity and ethylene gas from fruits and vegetables can cause rot or premature sprouting. A cool basement or garage is a much better choice.