15 Common Problems With Canna Lily Plants

Canna lilies are noted for being pest and disease free. Well, for the most part! Like all plants, they can and do develop problems in the right conditions. Canna lilies love hot and humid climates and these types of conditions are more susceptible to diseases.

You don’t have to live in hot and humid regions to experience problems with canna lilies. Cold regions have their own problems as well. Your region is going to have an impact on the types of issues you encounter. Disease or pests might be present in one region but not another.

But don’t fear! Most of the problems canna lilies experience are preventable. If they’ve already taken place, most have a solution. In this article, we will dig deeper into some common problems seen with canna lilies and ways to fix them.

Rhizomes That Don’t Germinate

You finally planted your canna lilies and it’s been weeks and nothing has germinated. This can be discouraging but here are some things to consider.

When planting the rhizomes, you may have planted dead bulbs. Before you begin planting look for thick, heavy rhizomes with 2 to 5 eyes each. If your rhizomes appear thin and mushy the chances are it’s not viable.

Each rhizome you plant should have eyes. During the dividing process, some rhizomes sections might not have eyes. Remember, eyes are the areas where shoots will emerge so we want plenty of eyes on the rhizome.

Another factor to consider is soil temperature. If you plant your rhizomes too early there is a chance of freezing. You will want to wait till soil temperatures are above 50ºF to plant. This will help prevent the rhizomes from turning to mush under the soil surface.

Water is also another factor in how well rhizomes will germinate. You should water your them daily until they begin to emerge. This will help hydrate the rhizome and encourage proper growth. Once they emerge you can water less frequently.

Yellowing Leaves

Your canna lilies leaves are turning yellow and now you’re wondering what could be the problem? Yellowing leaves are usually your first visible sign that something is wrong. Identifying why they are turning yellow can be a little more difficult. You will have to do a little detective work to determine the cause.

Common causes could be over or underwatering, not enough sunlight, or pests and diseases. Watering and sunlight are the usual culprits of yellowing leaves. Rhizome rot will turn the leaves yellow and then the leaves will die rather quickly.

Overcrowding 

It’s mid-summer and you haven’t seen a single bloom but there is plenty of foliage, what’s the problem? Canna lilies spread rapidly and if they don’t have enough space they can become overcrowded. Leave anywhere from 12 inches or more of space between each rhizome to allow for spreading.

Overcrowding will kill new shoots and prevent continuous blooms. As they spread, their canopy will start to close in and less sunlight can reach the soil surface. Those new shoots need sunlight to grow. If the canopy is too dense, the new shoots won’t have enough sunlight to continue growing.

If you believe your plants are too crowded, there are solutions. You can remove foliage that is finished blooming to allow sunlight for new growth. Also, you can dig up a few rhizomes to keep them from spreading more.

Rhizome or Root Rot

Rhizome rot, or also known as root rot, occurs in poorly draining soils that experience too much rainfall or water. A fungus known as Sclerotium rolfsii and fusarium spp is what causes the rhizomes to rot. The fungus spreads from the base of the plant up the stem and is cottony in appearance.

If you notice rhizome rot, remove the infested plant and the root mass. To prevent rhizome rot in the future, thin your canna lilies every few years. Planting them in a new location after lifting will help prevent fungal growth.

Rust

One of the most common diseases you’ll find on canna lilies is rust. The rust produces spores that move through the air or by water. The rust is powdery and red-brown in color. This disease is produced when conditions are humid and water is present on the foliage for a long period of time.

Rust spreads quickly and is hard to control once it gets going. There are a few ways to remove rust from infected plants. Remove all infested leaves, stems, or even whole plants. By removing plant parts or whole plants, you can mitigate the spread of the disease.

Botrytis Blight

This particular blight affects the flower of canna lilies. It will appear as a fuzzy, gray mold. Botrytis blight thrives in cold, rainy weather and is commonly seen during the spring months.

If you want to control the spread of the blight, remove any infested flowers from the stem. Be sure to place the discarded flowers away from your garden and do not compost them. Blight can spread easily and overwinter on other plant material.

Canna Yellow Mottle Virus

Canna yellow mottle virus causes streaks of pale tissue which can be seen between the leaf veins. As the virus progresses the tissue will turn brown and die. This virus can cause stunting, poor growth, or death of the plant.

There aren’t many methods of control for viruses in plants. Controlling aphids will help limit the spread of the virus. If you are having problems with viruses, do not propagate from these plants. The virus will carry over from year to year and most likely get worse.

Leaf Rollers

The leafroller is the caterpillar stage of the Brazilian skipper. They chew straight rows of holes in the leaves by rolling them up and eating them from the inside out. The caterpillar will be dark green with a white stripe on each side of its back.

An infested canna lily will be shredded and new leaves will not open. If there is extensive damage, the leaf will die. These pests overwinter in dead leaves, so it is best to remove all dead foliage at the end of the season to avoid a summer infestation.

Aphids

The dreaded aphid. We have all had experiences with aphids at some point while gardening. Aphids aren’t picky and will infect any green, healthy plant insight.

They constantly produce new growth, which is ideal for aphids. They latch onto new growth and suck the juice from the leaf tissue. Catching aphids before they get out of hand is important. You can also introduce predatory insects to control them, such as ladybugs. Aphids are known to transmit viruses from plant to plant.

Japanese Beetle

These particular beetles feed between the veins of the canna lily leaves. Japanese beetles like to hide on the underside of the leaves. If you see any beetles remove them from the leaf. This is easier to do if you catch them early on.

If you have a large infestation of Japanese beetles, you can spray a diluted dish soap and water solution on the plants. There are also a few other effective strategies to get rid of them as well.

Snails

Another pest that can cause damage to canna lily leaves is snails. They will puncture holes in the leaves and flowers while leaving a slimy trail.

If you can catch these little guys you can remove them by hand. They tend to be most active during night hours, so this may be difficult to do. They can be prevented by keeping the garden free of debris. Consult your local greenhouse on other methods of controlling snails if they are a problem.

Overwatering

You might be thinking, since canna lilies are tropical plants, they need tons of water. Well, this isn’t necessarily true. Even though they need regular watering, they shouldn’t be in soggy soils. This encourages root rot and will ultimately kill your plants.

Canna lilies like well-draining soils. If you notice pooling water around the roots days after watering, this is a sign your soil isn’t draining well. This simply means you shouldn’t water them as often. Give the soil time to drain the excess water. Once that water is gone, check the soil and see if you should water it again or not.

Underwatering

We all forget to water our plants every now and then right? I know I do! But underwatering can really be a big problem. They won’t grow dense, lush foliage, and vibrant blooms as quickly.

If you notice that your canna lilies have started to tear and rip, this is a sign they need more water. Luckily, the tearing and ripping don’t hinder their growth to the point that you notice. It’s the plant’s way of telling you it’s thirsty.

Always check the soil around the base of the plant. This will help you determine if they need to be watered or not. The soil should always be moist, but not waterlogged. If you are having a difficult time keeping your soil moisture high, consider adding mulch which will help retain moisture.

Blackened Foliage

If you start to notice blackening foliage, this is typically a sign that your region has had frost. This usually happens during the fall but can happen sooner depending on the weather. Once your canna lilies foliage turns black, they are done for the season.

Dig up the rhizomes once you notice black foliage so they don’t get damaged by frost. The first frost is enough to initiate dormancy and they are ready to be lifted. Follow proper overwintering storage and wait to plant until spring.

Improper Overwintering

Canna Lilies can be treated as perennials in warmer climates. But if you live in USDA zones 3-7, you will have to overwinter canna lilies. This process is pretty simple, but if not done correctly, it can kill the plant.

If you don’t store them correctly, they can freeze or sprout overwinter. Choosing the correct location to store them is important. They need a dark, cool location that won’t fall below 32 F. Common locations are a garage, cellar, or unfinished basement.

If your storage location is too warm, the rhizome can sprout and cause them to rot. Regularly check them during the winter to ensure they haven’t started to grow. If you notice them starting to sprout, don’t panic. Move them to a different location that has cooler temperatures and less light.