The canna lily is known for its tropical beauty and intricate blooms, which can at first glance give an impression of being high maintenance and difficult to grow. But happily, the flowering species planted in potted form are delightfully easy-keepers, especially if you’re in USDA hardiness zones 7-11.
They aren’t fans of colder weather but don’t be deterred by that. As with everything else about them, the requirements for colder-weather maintenance are pretty minimal.
At the end of this article is a special bonus for our readers: 2 container + 1 flower bed = 3 total flower garden designs. Layouts, plant palettes , and plant quantities all included. Ready for you to follow to the letter or use for inspiration. Have fun!
The Canna Lily Misnomer
Any plant with “lily” in their name is, right off the bat, going to cause some confusion at some point.
Canna “lilies” (pictured on left) are not related to true lilies at all. They are however related to the tropical bird of paradise, pictured on the right.
True and False Lilies
Do you know what every plant and flower on the following list has in common? Take a look:
If you said not a single one of them, genetically speaking, is a lily, you are correct! Well done.
Someone, somewhere, thought adding “lily” to the names of plants that weren’t lilies was a good idea, enough people bought into it, and voila! “False lilies” were born.
For your reference, only a plant with the Lilium genus in their botanical name is a “true” lily. All other “lilies”, if their genus name is not Lilium, are considered “false.”
There doesn’t seem to be a clear-cut answer on how this happened or which flower had the dubious honor of carrying the false label first. It appears to have started when referencing flowers that merely resembled true lilies. People in the growing and nursery business, looking to increase profits, likely did so to enhance their appeal and encourage sales.
To the untrained eye, and perhaps even a trained one, it’s not hard to see how they could be thought to look like true lilies (pictured on top).
These days, most, if not all, industry professionals do not add “lily” to the name. Despite that, the inaccurate nickname persists, as labels that old often do
Fertilizer vs. Soil Amending
Cannas are said to be heavy feeders and therefore in need of regular fertilization. Even better for them is healthy soil with natural nutrients. With the right soil, fertilizers aren’t needed.
I’ll get straight to the point: in a desirable growing environment, cannas don’t need fertilization. Here’s why.
Fertilizers aren’t food, despite what their labels may say. If it’s plant food you’re after, consider all natural options you can make at home. What fertilizers do is nutrify inert soil by adding supplemental nutrients, and in so doing, aid plants with carrying out specific growth processes.
Cannas use their roots to access these nutrients and feed themselves, as all plants do. If your cannas are in a location where their specific biological needs – for a certain amount of sunshine, water, and acid in their soil, as examples – are being met, you’ve already given them everything they need, and they can efficiently feed themselves. When that happens, they do not need the extra help.
This is why it’s so important to take periodic soil samples, have the samples tested, and then perform soil amendments as needed. If amending is needed, fertilizers offer the fastest solution, but the effects wear off quickly. Amending soil with natural, organic materials like compost, horse manure, or coffee grounds takes longer on the front end but results in more even nutrient coverage, lasts longer, and doesn’t present chemical harm to pets, children, or the plant itself.
Horse manure is an all-natural and organic way to amend your soil. It results in improved soil structure and better moisture retention.
Vitamins or hormones, on the other hand, are a direct benefit to the cannas’ growth on a cellular level. They are the catalyst for triggering specific growth-promoting chemical reactions inside cells. This applies to sick plants as well, as chemical reactions can be triggered that promote healing.
It’s worth mentioning that most fertilizers will attract aphids, and aphids are regarded as aggressive spreaders of viruses amongst cannas. Slowing down the spread of canna lily viruses at this level could contribute to the mitigation of a global problem in a big way.
The right soil can have your cannas looking gorgeous all season long, like this lovely dark pink specimen.
In summation, here’s your pre-planting soil checklist:
- Choose an area that gets about 6 hours of full sunlight and has excellent drainage.
- Perform a soil test in the area where you will be planting the cannas; aim for a pH around 6.5, which is slightly acidic.
- If necessary, increase the acidity (which means decrease the pH) by adding fresh coffee grounds to the soil or watering the soil with vinegar diluted in water.
- Or, if necessary, decrease the acidity (increase the pH) by adding wood ash or bone meal.
- If phosphate levels are low, raise by adding organic compost, manure, or clay. Cannas need a healthy presence of phosphate in their soil.
- Have some liquid supplements, vitamins or hormones on hand for planting and as-needed going forward. The original SUPERThrive formula is perfect. I swear by it, I’ve used it on everything, and it’s amazing stuff.
If you can follow that pre-planting checklist, cannas will be the easiest flower you’ve ever grown, and they will look stunning. You will reduce the maintenance required and decrease the possibility of health issues during the growing season by about 90%.
Planting, Growing, and Caring for Cannas
The seeds of a canna lily plant, which develop when the petals have fallen off. They start off green; don’t remove them until they are black, as shown. Cut them off the plant just below the stem using your bypass pruners.
Step 1: Plant at the right time of year
Wait until all threat of frost is gone for the season before planting any Canna plants or rhizomes. This time frame will vary a bit depending on where you live. Generally speaking, once the soil is hitting around 60 degrees, you should be in the clear.
The exception to this is starting from seed. If you prefer that route, you can start earlier in the year as you will keep the seeds inside while germinating.
Step 2: Choose a starting method
Here are your three options:
- starting from seed
- growing from rhizomes
- planting plants
My recommendation is unequivocally option #3: go to a reputable nursery and have one of the growers help you pick out some nice 1-gallon sized specimens. Some nurseries may offer 4″ pots or 1/2-gallon size, but those are harder to find. I prefer to use plants for a few reasons:
- Flowers that result from rhizomes are more susceptible to health issues which include spreading viruses. Specimens purchased from a nursery are started in a controlled environment and are generally virus-free. We’ll go into this in more detail coming up shortly.
- Store-bought or gift-given seeds and rhizomes do not come with history or context and are completely unpredictable. Unless you are doing your own propagating, you will miss out on potentially valuable knowledge that nursery plants offer. The nursery should be able to give you some breeding information that will help you know what to expect and prepare for moving forward.
- Both seeds and rhizomes can more easily result in an overcrowding situation down the road. Cannas hate to be overcrowded and will stress due to choking. Though small and immature at 1-gallon, a nursery plant still provides context regarding growth pattern, structure, number of inflorescences, etc., taking the guess-work out of determining how much space your cannas need.
- Starting from seed is not easy, and it is time-consuming; an important chunk of the growing season is lost to waiting. Rhizomes are easier to grow, but there is still a time factor. Nursery plants offer immediate impact and gratification upon installation, allowing you to enjoy their beauty right away.
Step 3: Determine where you are planting
Your options here are:
Cannas thrive in the moist environment of a water garden, and add a refreshing pick-me-up to a boggy area.
Cannas are easy to plant, meaning there’s one basic planting process that applies whether they’re going in the ground or a container. Aquatic planting varies a bit and does exclude seed-starting, but it’s still easy. If you have your heart set on starting from seed, you’ll need to plant in the ground or a container.
These plants are very versatile so now is a good time to get creative while also meeting any utilitarian needs. For example, if you’ve been in need of some sort of privacy hedge, or something to separate two distinct areas of the garden, cannas can do that for you. Mix them with other plants of varying heights to soften austere hardscapes or cover large expanses of property walls. Plant them anywhere in your yard where you’re trying to attract hummingbirds or butterflies. Consider adding just one or two particularly showy specimens – for example, a ‘Black Knight’ – to a rock garden or hardscaped area; a pop of color like this in an otherwise monochromatic, minimalistic space gives a striking, modern look.
Adding two or three showy specimens to a minimalist space creates added visual interest with stark contrast. The above “before” picture is a nice, clean space but the addition of unique plants in the below “after” picture gives the space more purpose.
Whatever you decide, remember that for big, bright blooms, your cannas will need a good six hours of direct sun every day. They will survive in the shade if forced to; keep in mind blooms will be small and unremarkable, and foliage will be larger and denser.
If you want to keep your canna lily indoors, you can certainly do so, just move the pot outside for it’s daily sun bath and pull her back in when she’s done. She may require some assistance in the event she misses a little sun time. In that event, some natural supplements will provide the needed boost.
Step 4: Plant your seeds, rhizomes, or plants
At this point, you should have already gone through the germination process with your canna lily seeds. Once you have about 6″ of sapling showing, you can transfer to a pot. I would recommend leaving this in a pot for a growing season, and then transplanting to either it’s new container or ground location the following season.
Here are your basic spacing guidelines for in-ground plantings:
- Dwarf canna lily – 18″ – 24″ (1-1/2 to 2 feet apart)
- Standard canna lily – 24″ – 30″ (2 to 2-1/2 feet apart)
- Giant canna lily – 36″ – 42″ (3 to 3-1/2 feet apart)
Cannas make the container gardening experience very satisfying by being easy to work with and looking great with virtually any style, shape, or color of pot. Choose a pot with plenty of room for root-growth, and don’t forget the drainage holes.
In a container, this does not feasibly apply as you won’t have space, and the overall look you’re generally trying to achieve here is full and almost overgrown. If you plan to winter your cannas to use again next season, this also means you’ll have to divide the rhizomes more frequently to prevent overcrowding and choking. If you are using them as annuals/seasonal color only, you don’t have to worry about this.
Turn the topsoil down to a depth of about 12″ for rhizomes or 18″ for plants. If the soil requires, add the necessary amendments and mix in during turning. If planting in a container, ensure you have one large enough to allow for root system growth. Make sure it has large enough drainage holes. While you can always transplant when your container is overgrown, I would err on the larger side to start to save a transplant down the road. Fill your container with the proper soil mix. I’ve worked with the Espoma and Osmocote soils quite a bit and always had consistently nice results.
Ground: Within this turned and amended soil, dig a small hole about 2″ or 3″ down for rhizomes, or deep enough to cover the potted root ball of the plant. For plants, allow 1-1/2 to 2 times the width of the root ball. Place one rhizome or one plant in the hole (with the eyes facing upward on the rhizome). Do this for every rhizome or plant, remembering the necessary spacing requirements.
Close-up of canna lily rhizomes with newly sprouted saplings. Rhizomes are underground stems and need to be dug up and divided every spring to prevent rhizome overcrowding.
Container: Follow the same outline as for ground planting, but plant just a bit deeper. Put your rhizomes down 4″ to 6″. If using plants, just cover the tops of the root balls plus allow for room for an inch or two of backfill.
Ground and container: When all rhizomes or plants have been placed, backfill each hole. Smooth out the soil for a nice, level appearance. Press the topsoil down firmly, and give all newly planted rhizomes and plants a thorough saturation with water. Add a thin layer of mulch over the top of the planting areas.
For any particularly tall plants, attach them to a small nursery stake for support. This is particularly important if you live in a windy climate. This is something to keep an eye on during the growing season as they mature.
Aquatic planting: Find an area to “plant” in that is deep enough to cover your pots less 2″ (you’ll be leaving about 2″ of the pot above the waterline). If using plants, you can use whatever nursery containers the cannas came in as long as they are not root-bound. If they are root-bound, you will need to transfer the root balls to slightly larger pots.
If planting rhizomes, 4″, 6″, or 1-gallon size pots will do well.
Canna floaters are a fast and fun way to try your hand at aquatic gardening while dressing up a water feature, or even a large basin or
receptacle. All you need is a board with holes cut to the size of your baskets, two baskets, two plants, and the backfill material for the planting baskets (mud pie mix or clay beads).
Rinse everything thoroughly – rhizomes, the soil from the root balls of any nursery plants, and the insides of the containers you will be using. Rinse thoroughly but take care not to damage any root fibers. If any of the pots are mesh or have drainage holes, line them with newspaper or burlap.
Now fill your pots to about 2″ or 3″ shy of the top of the container. What you fill with is going to come down to your personal preference, experience, and what works for you. Many people use regular all-purpose potting soil, and that’s fine. You can also use organic clay beads; they do float when new, so soak them prior to adding to your pots.
A third option is the “mud pie” mix. Instead of potting soil, use clay. If you cannot find clay, use a potting mix that is specifically formulated for ponds or aquatic planting. In the event that is also unavailable, you can create your own blend using a 3:1 ratio of sand and potting mix (75% sand, 25% potting mix). Mix your soil medium with water from the pond or water feature to create a little “mud pie” type mixture.
A cluster of red cannas thriving along the shallow shoreline of a pond. Cannas and water lilies make great companion plants.
Regardless of whatever medium you choose, remember to leave the 2″-3″ space at the top. This will be used for small pea gravel or small rock. After adding your rock cover, force the contents to settle and release air pockets by tapping the bottoms of the pots on the ground.
Slowly and carefully submerge your pots into the water, holding upright and in place for a minute or two while the dirt in the pots redistributes, and more air is released. Remember to leave about 2″ exposed and out of the water.
If you’re going to fertilize, only use blends that are specifically made for ponds or water features. Steer clear of timed-release products as they have been known to increase algae production. Fertilize at most once a month, less if you can.
Step 5: Caring for your growing cannas
All your newly planted cannas can now stay in their new environments for at least one growing season. Water cannas will need to be removed when it starts getting too cold, and either prepped for wintering (put in storage to use again next season) or disposed of.
Cannas in the ground can remain if you live in an area where evening frosts do not occur. A frost will kill the rhizomes. In Arizona, we do get frosts every winter so in-ground cannas are usually used as annuals here. When the first frost hits, you can either remove them and prep for wintering or dispose of them.
A Canna lily rhizome ready to be separated, cleaned and put away for winter storage, a process known as “overwintering.” Image: “Blumenrohr (Canna indica)” by blumenbiene is licensed under CC BY 2.0
Container cannas will need to be pulled inside for the winter if outside temperatures are too cold. As long as they are warm enough, you can treat this as a perennial and leave them in their container season after season until the container is outgrown.
During growing seasons, maintenance will consist of these four key components:
- Water: Even though drainage is important, Cannas like moisture-retaining soil and do not like to get too dry between waterings. In dry climates, plan to give your plants a long, deep watering once per week. In hotter and drier than usual conditions watering more frequently may be needed. If you see the soil looking dry, it is time to water. Don’t be afraid to treat them to a foliar spray as well.
- Temperatures/sunlight: One of the reasons sunlight is so important to cannas is because of the heat it puts out. Cannas need heat to bloom, and they need warm soil for the rhizomes to survive and grow.
- Deadheading: Spent blooms are noticeably unsightly and can detract from the visual beauty of the plant. Plus, removing individual blooms once spent encourages new growth. Simply snip off with your Corona bypass pruners, anvil pruner, or pinch off by hand. Temperatures/sunlight: One of the reasons sunlight is so important to cannas is because of the heat it puts out. Cannas need heat to bloom, and they need warm soil for the rhizomes to survive and grow.
Here’s a quick video how-to that shows you right on the canna lily how to remove the spent bloom:
- Diseases and pests: For quite a long time, cannas were known for having very few issues with diseases and pests. Unfortunately that is not currently the case. Canna lily virus – which sounds eerily similar to another virus we’re all too familiar with these days – shocked the horticulture community worldwide by suddenly bursting onto the scene in the early 2000s and taking only a few years to infect a large population of cannas all over the world. The problem is so serious that large growers have had to close their doors. There are several but the two thought to spread the easiest and cause the most destruction are:
- canna lily yellow mottle virus (badnavirus/CaYMV) – known for being easily spread; can infect all canna lily within proximity; can cause death
- canna lily yellow streak virus (CaYSV) – same as above; symptoms of both include stunting, shape distortion, streaking in the leaves and color ‘breaks’ in the flowers
The spread of these viruses has been exacerbated by rhizomatous gardening. The popular practice of vegetative propagation of cannas – splitting rhizomes to make new plants – is now known to contribute to the spread of viruses. This is compounded by the other common practice of overwintering canna lily rhizomes to use again the following season; if this is done with an infected rhizome, it could cause the spread of a virus throughout the entire garden, into the following season. Viruses are then spreading year to year, and even multiple times a year, with different plantings.
A canna lily leaf infected with Rust, which is spread by spores. Every part of this plant that has been in contact with the spores has to be burned. Image: “Rust of canna lily (Canna indica), caused by Puccinia thaliae” by Plant pests and diseases is licensed under CC CC0 1.0.
Because it’s thought to be spread by aphids – and remember, aphids are attracted to fertilizers! – there’s no chemical control. The only ways to contain it are to prevent it: buy healthy plants and stop performing home propagation. I would say avoiding fertilizers and being on high-alert aphid patrol are likely to aid in prevention as well.
While I understand the appeal of bulb and rhizome gardening, it is important that we consider what is best for the ongoing and future health of our gardening resources. This is why at this time I would encourage you to do your canna lily gardening with potted plants. They can still be used as annuals in colder climates, or as perennials in containers that can spend winters indoors.
Nurseries are diligently working to eradicate the problem and have systems in place to maintain inventory that is virus-free. Many nurseries have stopped selling canna lily rhizomes altogether and now only sell potted plants as it’s the only way to ensure they are not spreading viruses.
If only the cannas could wear masks…
Cannas also struggle with rust, which is a fungal infection spread by spores. If you see orange-colored, powdery deposits on the leaves, act fast. To contain: remove, burn, bag, and trash all affected parts. Do this away from other plants, and do not compost these parts. If further treatment is still needed, treat with a chemical fungicide.
Pests that are problematic for cannas include the greater and lesser leaf roller, Japanese beetles, bagworm moth larvae, and the virus-spreading aphids. Aphids are easy to remove by simply wiping or knocking them off. You can also spray with soapy water or a neem oil solution.
Canna lily foliage that has been destroyed by the larvae of the bagworm moth. Eggs can be pulled off and disposed of. Actual larvae must be treated with insecticide. Image: “Canna lily (Canna indica): Bagworm moth larvae feeding injury” by Plant pests and diseases is licensed under CC CC0 1.0
If your cannas are going to stay in the ground during winter, you’ll have snails and slugs with which to contend. A homemade garlic spray that harnesses the all-natural power of Allicin as a deterrent is the best way to keep these pests away.
Just a last reminder about fertilizer: if you opt to go that route, remember the potential issues with attracting aphids, and aphids known involvement in spreading viruses. I would again encourage you to use organic products, or even better, all-natural supplements you can make at home.
The Amazing Vitality of the Canna Lily
I always loved working with this species. She’s a beautiful flower and adds an effortless kapow! to any space she happens to occupy. There is far more to these enigmatic plants than you see on (or above) the surface. She is bursting with life, and it’s a beautiful thing.
See for yourself:
Special Bonus: 3 Flower Garden Designs
Whether you’re looking for an outline you can follow start to finish, or just some inspiration to get your own creative ideas churning, I’ve compiled three options for you.
The first two are for containers, and you will need large to extra large pots for both layouts.
If you decide to use smaller pots, you will just need to adjust the plant count down to accommodate.
I hope one of these layouts works for you. Enjoy!
Container Option #1
Qty 4 – 1gallon pink (or whatever color you prefer) cannas
Qty 4 – 1gallon chili pepper plants*
Qty 6 – 4” pots Calibrachoa ‘chameleon sunshine berry’
Qty 2 – 6 packs (so buy 2 separate 6 packs for a total of 12 little plants) blue Lobelia
Container Option #2
(3) 1-gallon Canna ‘Black Knight’
(3) 1-gallon Caladium ‘Berries’ Burgundy’
(3) 1-gallon Society Garlic
(4) 1-gallon variegated Bleeding Heart Bower vine
(3) 4” pot potato vine ‘Black Heart’
Option #3: In-ground Flower Bed