How to Overwinter Your Canna Lilies in 6 Simple Steps
Are you wanting to overwinter your canna lilies this season? These beautiful flowers need to be taken care of if you want them to rebloom properly next season. In this article, gardening expert Paige Foley walks through the exact process you'll want to follow to keep your canna lilies safe before first frost!
Canna lilies are one of the easiest plants to overwinter and don’t require a special greenhouse or growing light system to do so. Canna Lilies are considered a perennial but in colder regions act more like an annual. They require you to lift the rhizomes from the soil so they don’t freeze during harsh winter conditions.
But overwintering only applies to certain hardiness zones. Overwintering is very common amongst certain bulb plants, like Dahlias and Begonias.
So – if you do have to overwinter your canna lilies, how exactly is it done? Keep reading as we dive into what hardiness zones these tall blooming perennials require overwintering, as well as how to do it. Ready to learn more? Let’s dig in!
Overwintering By Hardiness Zone
If you live in USDA zones 3-7, you will have to remove your them from the ground and replant again in the spring. If you decide to leave the rhizomes in the soil during freezing conditions, they will not regrow. You will have to purchase or replant lifted rhizomes in the spring.
If you choose to grow your canna lilies in a container then your job is even easier. Simply, bring the container into a cool, dry area for the winter. It’s that simple! If you want to transplant them to a new container, dig up the rhizomes from the old container and place them in the new container in the spring.
Zones 8 and above are in luck, you can leave them in the ground year-round. If you are concerned you can always place straw or mulch over the plant for an added layer of protection from potential frost.
Rhizomes can easily be stored in a basement, garage, or cool, dry space. They should be in total darkness and no heat. I prefer to place them in a large heavy-duty black trash bag in my insulated garage.
You have worked hard all season to keep your these tall blooming beauties full and lush. It would be a shame to lose them to improper overwintering.
Why Overwintering is Necessary
Canna lilies produce thick, fresh rhizomes near the soil surface. The rhizomes are sensitive to freezing conditions. Rhizomes are made up of mostly water and when exposed to freezing soil conditions the water expands and causes the plant cells to burst. When the plant cells burst, the rhizomes die and are unable to produce sprouts in the spring.
If your region experiences freezing temperatures, you should dig up the rhizomes and store indoors overwinter. If they are left in the ground to overwinter they will turn to mush and will not regrow in the spring/summer.
If you are on the border of zone 7 and 8, it’s a gamble on whether your region will receive frost. If you don’t have the time or simply don’t want to dig them up, you can place straw or mulch over the plants as mentioned earlier. This should be enough to protect the rhizomes from a light frost or two.
If you live in a region that doesn’t experience frost, you’re in luck! They can stay in the ground and will regrow in the spring. If you want to transplant or simply add more to other areas, dig them up in the fall and store in a cool, dry place til spring.
Step 1: Timing
If you live in zones 3-7, the best time to start digging them up is when temperatures become frosty and the leaves begin to die. You will know when your canna lilies have been affected by frost when the leaves turn yellow to black and foliage begins to fall to the ground.
Let your canna lilies experience one to two frost before considering lifting from the ground. Freezing temperatures initiate dormancy which is needed to successfully store the rhizomes. Don’t let them sit in the ground too long because the frost will kill them. You don’t want to start digging and find out nothing survived.
If you are growing in containers, wait until the first frost. Once the foliage has turned yellow, you can begin the overwintering process.
Then move the container to a cool, dry place until spring. This is convenient because it doesn’t involve digging and curing. Make sure your soil is dry before placing it into storage. Wet to damp soils can initiate germination and lead to rotting rhizomes.
If your plants start to sprout in the container during winter, move to a cooler area. Always monitor your containers for sprouts. If you catch sprouting soon enough, there is a high chance of saving the plants.
Step 2: How to Dig Them Up
Their rhizomes are fragile so carefully dig around the area with a digging fork, hand spade or shovel. The rhizomes will be in clumps close to the soil surface. They have shallow roots which make them easy to lift from the ground.
Once you have the rhizomes dug up, shake off or rinse the soil from the rhizomes. We don’t want any excess soil on the rhizomes. This can lead to rot and diseases in storage.
Before you start digging, remove the dead foliage from above the rhizome. Once you have dug them up, inspect the rhizome for any insect or animal damage and discard the damaged rhizomes. The rhizomes will vary in size so you can cut them to make them smaller. Cutting the rhizomes will not damage them or affect their storage. Shake off excess dirt and store in a dark tote or black trash bag in a cool area.
If you planted in a container, you can simply leave them in the existing container. Once the foliage has died from frost, cut the dead foliage a few inches from the soil surface and store in the designated storage area.
If you don’t want your canna lilies in a container anymore you can continue to store in the same container until spring. Or you can remove it from the container and follow the same process as overwintering from the garden.
If you are growing multiple varieties, it is best to label the outside of the container. All rhizomes look the same so to avoid confusion in the spring, label the variety on the container.
Step 3: Storage
Arguably the easiest part of overwintering is the storage. You don’t need a greenhouse or special equipment to store them. All you have to do is identify a cool, dark place and purchase a dark tote or heavy-duty trash bag. The trash bag and totes will help maintain humidity without adding extra moisture.
Once you have dug up the rhizomes, leave them out in a warm, dry place for several days. This will help cure the rhizomes and help prevent molding and sprouting in storage. When they are cured, place them in your desired container. Do not close the bag or totes tight, as they are a living thing and they need to breathe!
Check your rhizomes once a month for rotting plants. Remove the rotting rhizomes from the container to prevent others from rotting. If your rhizomes continue to rot, consider moving to a cooler and dryer location.
You may have to try a different type of container to store the rhizomes in if the rotting continues. By switching containers and moving to a new location should help keep the rhizomes from rotting further.
You could also try adding newspaper or other paper material to the storage container to absorb some moisture. By monitoring them regularly, you can get ahead of any problems that may arise.
Remember, if you have multiple varieties, label the bags or totes with the variety name. Once you have them dug and labeled you can easily share your harvest with friends, family, and other gardeners.
Step 4: Finding a Storage Space
Picking the place to store them so they don’t freeze is rather simple. Identify a cool, dry place that receives little to no light. Below is a list of appropriate locations to store canna lilies.
- Unheated Garage
- Unfinished Basement
Avoid outbuildings such as sheds and barns. These types of buildings typically don’t have insulation and will get below-freezing temperatures. Temperatures in the storage area shouldn’t drop to below 32°F. If they drop too low the chance of the rhizomes dying is very high.
We have talked a lot about if temperatures fall below freezing but what is too warm of storage for rhizomes? The storage area also should not get above 50°F during the overwintering process.
If temperatures are too warm this will cause the rhizomes to germinate. If you don’t catch that the rhizomes have germinated there is a high chance of them rotting.
If your canna lilies sprout in storage, don’t fret. It’s common for rhizomes to sprout after digging up in the fall or throughout the overwintering process. If sprouting occurs, evaluate the storage area. Is it too hot? Is it not dry enough? If the answers are yes, consider moving to a different storage area.
Step 5: Removing Dead Rhizomes
Spring has finally sprung and you’re ready to start planting! How do you know what rhizomes are alive and which ones are dead? Let’s look at some key features to look for when sorting alive and dead rhizomes.
Dead rhizomes will be thin, soft, and squishy when you squeeze them with your hands. They can also be brittle, lightweight, and hollow. Healthy viable rhizomes will be heavy and firm. If you are still unsure, you can place the rhizomes in a bucket of water. If the rhizomes sink, they are healthy. If they float, they are most likely dead and you should discard them.
If you plant a dead rhizome, don’t panic. Canna Lilies multiply during the growing season and will most likely fill in any gaps where dead plants didn’t grow.
Step 6: Replanting
When temperatures increase and the risk for frost has passed, you can go ahead and start planting. Preferably when soil temperatures are above 50° F, you are safe to start. If you plant in cooler soils the chance of your canna lilies surviving is pretty high. The cooler soils will only inhibit germination and they won’t germinate until soil temperatures are warmer.
A good rule of thumb is if the tulips in your region are blooming, it’s safe to start planting.
Begin by inspecting your canna lilies for mold and diseases. Discard all bad rhizomes before planting. Rhizomes have eyes and these are the growing points of the plant. More eyes on the rhizome increase the chance of more shoots that will grow in the spring and summer.
Plant about 2-3 inches deep in the soil and about 12 inches apart. The rhizomes will multiply during the growing season and will fill in the 12-inch gap.
You can start them in your home or greenhouse 4-6 weeks before the anticipated last frost. Plant the rhizomes into a deep container. Water them thoroughly and place them in direct sunlight. If you are transplanting to a garden bed make sure soil temperatures are ideal and transplant.
Here is a short list of key points to take away when it comes to overwintering.
- If you live in zones 3-7, you will need to dig up your cannas after the first few frosts.
- Let your rhizomes cure for a few days before placing them in a tote or bag.
- Store in a cool, dry location.
- Label the variety on each container or bag.
- When soil temperatures are above 50 ° F, you can replant.
Canna lilies are one of the most versatile tropical plants to grow. They bring a tropical feel to even the coldest of climates. They are great for a beginner or experienced gardener. Understanding how to overwinter your rhizomes will ensure lush foliage and beautiful blooms for years to come. Good luck and happy growing!