Canna lily in pots

Mixed callas growing in a container. (Photo by Dugald Cameron)

In the fall, you can store calla and canna plants for next year. Both are easy to overwinter; here’s how:

Overwintering calla lilies

These wonderfully colourful plants are from South Africa. In their natural habitat, they grow and flower during the wet season, going dormant during the following dry season. Fortunately, these bulbs are super easy to store over the winter. They have a tough outer coat and equally tough interior, making them less likely to shrink during storage. Give them what they like and they’ll multiply like crazy.

If you’ve grown them in pots, cut off the foliage and bring them in before frost. Chances are they’re probably wet, and the tubers will be plump and full of moisture. If they’re dug out at this stage, they can be easily damaged, and the wound can cause your tuber to spoil during storage. Bulbs and tubers need to ripen in order to survive dormancy. They will slowly dry out, forming thicker, tougher coats that don’t mind handling. They like a cool, dark (but not freezing) spot.

If you really must unpot them, carefully remove the soil and re-package them in vermiculite or ever-so-slightly moist peat moss before storage. But why bother? This is a messy job and it’s easy to accidentally mix them up if you’re keeping track of different varieties. They’ll actually store far better left alone in their pots. It’s what I’ve done successfully for years.

If you’re wondering where to put all your pots, fear not. You can stack them once they’ve dried out. The only thing to watch for are early sprouts growing as your callas wake up. (They don’t grow too well under another pot!) This shouldn’t happen until late winter, but sometimes they surprise you. Keeping them cool helps prevent them from sprouting too early.

Overwintering canna lilies

These popular plants have adorned Canadian gardens for generations. Their lush, tropical foliage and non-stop flowering are one of the highlights of summer containers and gardens. They’re native to tropical Asia where they flourish in the hot, wet growing season; some species reach seven feet (2 m). Here in Canada, where our winters are hardly hot and tropical, our shorter days and cooler weather signal that it’s time to move them indoors. They hate cold weather, so bring them in when overnight temperatures get into the low, single digits.

Early signs of yellow streak virus on canna leaf.

Canna virus – a bad news, good news story

The bad news: Unfortunately, there is a nasty virus in virtually all the big cannas grown in France, Israel, the Netherlands, Australia and the U.S., which are where almost all the canna sold in Canada come from. The disease was first identified years ago but little has been done to stop its spread. It has spread throughout the large nurseries of the world, with only a handful offering virus-free, healthy stock.

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It’s known as yellow streak virus, and the name says it all. It first appears as faint yellow streaks in the foliage, increasingly spreading, eventually leading to distorted foliage and death. Like many plant viruses, it’s spread by sucking insects like aphids. There is no cure. Dispose of infected plants and surrounding soil in the garbage, not in your compost. The tragedy is you can’t see any evidence on the root or even early-season foliage. But the mature foliage in fall will show if the plant is infected, which leads me to…

The good news: Fortunately, the majority of cannas we grow aren’t bought. They’re traded, passed on, shared with family and neighbours or traded at horticultural societies. These have likely been around long before the virus even existed. If they’re healthy they’re probably fine. In fact, several canna nurseries and collections were saved by collecting healthy rhizomes from isolated virus-free gardens. So check your canna foliage carefully. If in doubt, throw them out.

Overwintering

Chop the foliage off a few inches above soil level. Cannas in containers can be brought indoors. If they’re in big pots, you’re better off lifting them as you would those growing in the garden. This requires some care because a healthy canna rhizome (root) will have grown a lot bigger over the summer.

Allow their plump, water-filled roots to ripen a bit before storage. Once ripened, you can remove any soil and place them in clear plastic bags filled with very lightly moistened (not damp) peat moss, storing the sealed bags in a cool, dark place. Check them from time to time to make sure they haven’t rotted (you’ll see a mushy area). Just cut this off, let the root dry off and re-store again in peat moss.

Overwintering Canna Lilies

Canna Lilies are tropical plants and don’t like freezing weather. If your winter is cold enough to freeze the ground then you need to bring in your canna lilies over the winter.

Digging up the Canna Lilies

The stems of the Canna Lily come out of large rhizomes. Most of the rhizomes will be near the surface in the top 10 inches or less. Occasionally if they bump against a wall or the sides of the pot the rhizome will grow downward. it’s quite easy to bruise or damage the rhizome so you need to dig carefully.

You can use a spade, or a garden fork. I’ve used garden trowel when I’m digging my Canna Lilies in large pots.

First step is to trim the stems about 6 inches above the root. This leaves a convenient handle.

If you have not used pesticides on your plants and you know your soil is safe, you can try tasting the inside of the stem. (It can be eaten in salads)

If I’m growing in a pot or a garbage can I invert the pot and tap the whole root ball out if I can.

If the Canna Lily is growing in the ground or a heavy pot then I carefully dig it out. I go all around the plant and carefully free it from the soil. Don’t worry if you cut through a rhizome. Just put any piece aside.

The roots fill the pot quite tightly and I had to tap and pull quite hard

Next step is to free the rhizomes from the soil. I mostly use my hands. Go slowly and gently. You can trim the long fleshy roots but be careful not to damage or bruise the rhizomes.

Trim the Roots of the Canna Lily

When most of the soil is removed, trim the thick roots. You can also trim the stems a bit shorter.

If the rhizomes are very large you can carefully snap them in large sections. I do this every year because I usually need smaller roots for the pots.

The Canna Lily rhizome should be allowed to dry out for a few hours. Don’t leave them in the sun and don’t allow them to freeze. If the soil is very wet dry them till the soil left is almost dry. This is to prevent your Canna Lily from Rotting. this lot of roots were very wet so I didn’t trim them till they’d had a chance to dry a bit.

Prepare a large box and have some peat moss ready. I use rubbermaid containers but if I had wood boxes or bushel baskets they would work well. Put a layer of peat in the bottom at least 1 inch thick. Carefully put a layer of rhizomes on top of the peat and cover them with peat. Put more rhizomes in and cover them. it’s important not to allow the pieces to touch otherwise they might rot. Cover the box with newspaper or plastic that has been slashed.

You want to keep your rhizomes from drying out completely but you don’t want any condensation. DO NOT use the rubbermaid cover. Your roots will rot.

I’ve seen people wrap their roots in newspaper instead of peat moss.

That’s it. Put your container in a DARK and cool place. It should be below 50 degrees F. otherwise the Canna will start growing too soon, or rot. I bring my plants in before the first frost and used to put them in the cold room in the basement. I’ve moved and lost my cold room. I now place them in the shop. I heat it just enough to keep it above freezing. The canna should be cool but not freezing.

I’m sure that the roots could be kept in a refrigerator if you could spare the space. In that case, wrapping them in thick newspaper would be useful.

During the winter, check on your Canna lily roots and make sure that they are not going mouldy because of too much condensation.

I’ve used this method overwintering my Canna Lilies for years. As soon as the weather warm up they start sprouting and it’s a race to plant them. You can also start them inside in pots to give them an early start if you have a sunny window. Check out my page on how to Grow Canna Lilies for more details

It is sometimes possible to overwinter your canna Lilies just by drying out the rhizomes a bit and placing them in a loose pile in a bucket. This will work better if your roots are not damaged or bruised and if you have a nice cold dry room for them. Check for mould and rotate the position of the roots. There will be some rot that way though.

I’ve also had success overwintering roots by allowing cannas which were planted in pots to dry out, after cutting the tops off I placed the pots in a cool dark place. In the spring I split the roots and replanted them. They are too root bound to stay in the same pot. Split them before they’ve had a chance to start growing.

Starting Canna Lilies from seeds

I try to be accurate and check my information, but mistakes happen.

email me if you find mistakes, I’ll fix them and we’ll all benefit: Christine

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Whether you love to fully immerse yourself in jungle-style surroundings with plenty of foliage and eye-catching blasts of bold, bright colour, or prefer to mix up traditional planting schemes with hints of exotic charm, lush and leafy Cannas are a well-rounded and easy-to-grow candidate that will really pack a punch in a sunny spot!

Why grow Cannas?

Cannas are a funky and impressive summer bedding plant, best known for their fabulous, broad architectural foliage and vibrant blooms. Many varieties have striped bi- or tri-colour leaves which bring interest to the summer garden as soon as they’re planted. Throughout summer, they’ll grow taller and continue to produce these fresh, richly-coloured leaves. Then, to really put the icing on the cake, you’ll get a fantastic display of big, bright flowers at the top of each plant for an exciting pop of colour which lasts from late summer through to autumn. With all this to offer, Cannas really do add a special season-long value.

Both tall flowering and dwarf cannas create a lavish foliage display that will pad out any planting scheme with colour. With an upright and columnar habit, whilst being impressive and grand, they have a handy narrow footing which means they can be enjoyed in a modest space – perfect if you want to plant a punchy group of them in a large border or pack them in to a small corner bed. Tall varieties are ideal for planting at the back of the border, and the dwarf varieties are a real gem, perfect for positioning in smaller spaces, containers or at the front of the border.

How to grow Cannas

Cannas are adapted to tropical temperatures and therefore not hardy in the UK, but despite this they do very well when used as a summer bedding plant. What’s more, they’re very easy to grow too. Supplied as rhizomes in the spring, it’s possible to get a great display from cannas by planting them directly outside in late May. But, if you have a heated greenhouse or conservatory in which to start them off in the spring, that’s the best way to go and they’ll already be looking fab by the time you get them out into the garden at the start of the summer!

Top tips for growing Cannas:

  • Start Cannas in temporary pots which are approximately 20cm in diameter. Grow-on in warm conditions such as a greenhouse or conservatory between March-May.
  • Three-quarters fill your pot with multi-purpose compost and position the rhizome across the soil surface with any shoots facing upwards. Top-up with compost so the rhizome is very shallowly planted with any shoots exposed.
  • Water in after planting and keep the pots hydrated, but not soggy.
  • In late May or after risk of frost has passed, allow your plants to harden off gradually by leaving them outside during the day and bringing them in at night for the first week or two.
  • Plant outside in pots or borders once the plants have hardened off. Carefully remove the entire plant and root ball from the pot and plant in an equal-sized to the root ball. Position the plants at a spacing of around 30-50cm.

Planting Cannas straight outside:

  • If planting cannas straight outside, wait until late May or after risk of frost has passed. They will be a little behind cannas which have been grown on indoors, but will still put on a good display of foliage from mid-summer onwards followed by flowers a little later.
  • Plant the rhizomes shallowly in the ground or in a container with multipurpose compost and cover over with soil so that any shoots are still exposed.
  • Water well after planting and keep well hydrated by watering every day until the plant is in full growth.

Canna aftercare:

  • Cannas require very little maintenance once in full growth, although they will benefit from a fortnightly feed using an all-purpose liquid feed from around mid-August. This will boost flowering and improve foliage vibrancy.
  • Deadhead your canna flowers regularly and they will go on to produce more blooms right through to the first frosts.

Overwintering Cannas:

  • As soon as frost is forecast, it’s time to cut back your cannas and decide how to overwinter them for use next year.
  • Cannas are not frost hardy, although they have been known to survive a mild UK winter and return for a repeat display the following year. If you live in a mild area or you have a sheltered or secluded garden and they’re planted in a sunny spot, you can often get away with just adding a very thick layer of dry mulch or compost over the rhizomes – this would need to be a good 20-25cm thick to keep the frost off.
  • To be on the safe side, it’s best to lift and store Canna rhizomes for winter. To do this, carefully dig out the rhizomes and shake off any excess soil. Cut back the stem to just 5cm and discard the old foliage. Then store in trays in a cool, dry and airy place throughout winter. They can then be potted up and used again from March onwards.

Tall Canna varieties

Tall cannas are perfect for growing at the back of the border where they can act as a lush and attractive screen. Alternatively, they’re the ideal choice for planting in dramatic groups in the middle of a wide border. But despite the fact that they’re tall, they’re quite narrow so you don’t have to have a huge space to grow them. You can also use them to create a bit of privacy or a secluded garden hideaway in a small space – perfect if your garden is overlooked by neighbours!

Here are three of our favourite tall Cannas:

  • Canna ‘Durban’

This Canna has possibly the most striking foliage of all, with pink, green and mauve striped leaves with hints of yellow. With almost a rainbow of colour just from the leaves, you’ll have plenty to look at throughout the summer season, followed by a big hit of extra colour from its vivid orange flowers from late summer onwards.

  • Canna ‘Stuttgart’

This unique Canna has wonderful green and cream variegated foliage which provide a bright and contrasting display all summer long. From late August onwards, you’ll be rewarded with plume of elegant apricot flowers to add a third splash of colour to the mix.

  • Canna ‘Louis Cottin’

The large mauve-tinged green leaves of this variety are the perfect addition to an exotic planting scheme, bringing that lush a dense display which forms the perfect backdrop for any surrounding brightly coloured flowers. In late summer it really comes into its own with a punchy display of apricot blooms.

Dwarf Canna varieties

Dwarf canna varieties are ideal for planting in large patio containers or in smaller or more forefront border spaces. There is a great choice of dwarf Cannas to grow, all with unusual foliage and flowers to bring long-lasting colour to the summer garden.

Here are our top three dwarf Cannas for inspiration:

  • Canna ‘Pink Paradise’

Your garden will look like a mini paradise with these bold beauties, flowering in late summer with wonderful coral-pink and intricately marked apricot flecks. The foliage is a rich bronze colour which sets the perfect contrast for the vibrant flowers as well as surrounding plants in your garden.

  • Canna ‘Fantasy’

This compact Canna is a real delight in the garden, producing a dense display of exotic, broad foliage throughout summer and then topped with stunning orchid-like blooms from August onwards. Each petal of these unusual cream-coloured flowers is patterned with a speckling with tiny salmon pink dots.

  • Canna ‘Vanilla Cream’

Perfect for more toned-down displays, or for use as highlighting plants if you already have enough colour! These wonderful cannas produce lots of lovely fresh green foliage throughout the season, providing good, strong structural show. Then from late August, you’ll get a fabulous show of plain cream-coloured blooms which last right through to autumn.

What to grow with Cannas

With their stunning, broad and intensely-coloured foliage, cannas are not only stunning n their own right, but they make the perfect backdrop for other summer flowers before they go on to produce their own vibrant blooms later on in the season. Plants with a contrasting habit and bright flowers make the perfect planting partners, creating a really full and long-lasting show that lasts all summer long.

If you’re looking for inspiration to make a power-packed summer planting scheme, take a look at some of our favourite Canna partners:

  • Dahlias + Cannas

Dahlias and Cannas have long been a popular pairing, both sun loving and flaunting a vibrant, tropical look with their blooms and foliage. Choose any type of Canna and Dahlia and they will undoubtedly look fantastic next to each other in a sunny border or patio planting scheme!

  • Bessera elegans + Cannas

Broad-leaved plants like Cannas create the perfect setting, allowing more delicate flowers like Bessera elegans to fully strut their stuff in front. The dainty but vividly-coloured flowers of Bessera will really shine when planted in front of a patch of Cannas, particularly dark-leaves varieties.

  • Anomatheca laxa + Cannas

Though flowering at different times, Anomatheca and Bessera provide a tropical-looking successive display which will last from early summer right through to autumn. The splashy salmon-pink flowers of Anomatheca laxa in early summer will contrast wonderfully against young Canna foliage, then gradually give way to the Canna flowers which will take over the colour display a bit later on in the season.

How to Grow a Canna Lily in a Container

Canna lilies are most easily grown from their bulbs. The canna lily creates exotic trumpet-shaped blooms which come in a myriad of different colors, producing blooms in every color. The paddle-shaped leaves compete for attention by being large and colorful, either green, blue-green, bronze, burgundy, purple or striped. Growing a Canna lily in a container will help you to keep this tropical beauty flourishing in temperate regions.

Benefits of Growing in a Container

The canna lily will sometimes survive a winter, but it is unlikely to survive outside below 25 degrees Fahrenheit. Growing in a container will insure protection for your canna lily during the cold months. Canna lilies are a hungry, thirsty plant. Although it will dry out quicker in a container, fertilizer will go farther in a container. The canna lily is a breath-taking plant that you don’t want to ignore. A container grown canna lily can be moved to wherever the action is in the house.

Preparing the Container

Start your bulb in a 6-inch container. Any type of container will work, but a black plastic container or clay pot will retain heat better; make sure your container has plenty of drainage holes on the bottom. To help with drainage and keep the soil for leaking out of the drainage holes, line the bottom of the container with a layer of newspaper and a couple inches of gravel or pebbles. Fill the container about 2/3 full with a compost-enriched potting soil. Pre-moisten the soil with warm water. Canna lilies require a rich, fertile soil, but they will also thrive in sandy soil as well.

Planting Canna Lily Bulbs

Spring is the best time to start growing canna lily bulbs. Place the bulb on its side with the growing eye facing up and cover with 3 to 4 inches of soil. Place the container on top of a saucer and water thoroughly. Keep the water in the saucer full so that the container can be watered from the bottom up. Place indoors out of the sun.

Caring for Container-grown Canna Lilies

Once the bulbs have sprouted, place in a south-facing window. Your blooms should begin to blossom within 8 to 16 weeks. Move outdoors in the summer to a sunny location. For best results place where they can receive morning sun and afternoon shade. Water weekly throughout the summer Canna Lilies respond well to organic fertilizers, such as blood and bone or well-rotted cow manure. Or you can use a 20-20-20 liquid fertilizer every other week. Move the container back inside in the autumn before the first frost. Reduce watering during the winter months, keeping the soil more on the dry side. Cut off the blooms down to the bottom of the plant stem at the end of the summer, but keep the foliage in place as it will keep your plant healthy.

Move the canna lily outside the following spring after the last frost of winter.

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Canna lilies aren’t really lilies. And they really don’t look very lily-like at all. But that is not a bad thing, because while regular garden lilies are spectacular, they don’t hold a candle to canna lilies when it comes to leaf colour, pattern and size.

Canna lilies are perennial plants in climates much milder than ours, but they do grow phenomenally well here during the summer, thanks to our long, sunny days.

Cannas begin as specialized roots called rhizomes and from there, waste little time in generating shoots. With warm sunny weather, it is not uncommon for cannas to grow two or even three metres tall in a single season. A bonus with cannas is that they develop multiple shoots below the soil surface, resulting in a nice, dense cluster of tall shoots emerging from a single group of rhizomes.

ITS HISTORY

Canna lilies are native to the Americas and are found in tropical forests, along rivers, or in wetlands. They have really come into their own as ornamental plants within the past 10 years or so, and now are quite common in gardens and large pots right across the country.

Now, I have had – quite literally – an up-and-down relationship with cannas. A few years ago, I grew in a pot on my deck a huge one just over a metre tall and just under a metre wide. And thanks to my careless movement of this giant potted plant, I managed to lose control of it and helplessly watched it tumble violently down 13 concrete patio steps before coming to rest against the bumper of my car. The plant, plastic pot, and car survived relatively unscathed, but my pride took quite a beating that day.

BEST FEATURES

Although cannas produce beautiful spikes of flowers, the leaves are undoubtedly its best feature.

The leaves come in a gorgeous array of patterns and colours and two of my favourite varieties in this category are Pretoria and Australis. Pretoria produces green-andgold-striped leaves that are reminiscent of the stripes on a tiger, giving it its other name, Bengal Tiger. The bright, rich, orange flowers are also very striking and complement the foliage beautifully.

Australis is another great one.

It produces solid, deep-burgundy foliage that blends beautifully with mauve petunias and yellow sweet potato vine.

DEGREE OF DIFFICULT: EASY

Cannas may be indigenous to tropical and semitropical regions, but they are easy to grow here with about six hours or more of direct sunlight per day. With less light, the plants will still be showy, if a little shorter and with fewer leaves.

Perhaps the biggest challenge with growing cannas is to ensure that you buy virus indexed plants. Virus indexed means that the cannas are free of a destructive virus that stunts the plants and creates large brown streaks on the foliage. This virus won’t spread to any other garden plants, but it certainly compromises the health, vigour and beauty of cannas.

Ask your garden-centre horticulturist which canna varieties have been virus indexed. Non-virus indexed may still be virus free, but why take a chance?

HOW PERFECT IS IT?

Canna lilies top my list of best container centrepieces. They grow rapidly, produce multiple stems, develop great leaves and flowers, and are pretty much pest free.

And, of course, any plant that can tumble down concrete stairs, survive smacking into a car bumper, and still leaf-out and flower beautifully, is my kind of plant.

To keep abreast of what’s new in the gardening world, follow facebook.com/HolesGreenhouses.

Cannas: hot, tropical and easy to grow

Next summer I plan to plunge large pots of my intense pink Canna ‘Iridiflora’ in the corners of my long pool to contrast with the flat plates of my white water lily. Canna ‘Iridiflora’ is my all-time favourite, and possibly my all-time favourite plant. Also known as C. x ehemanii, this is undoubtedly one of the hardiest and most striking cannas. Mine have been left out in my East Midlands garden for several years now.

Many gardeners do not grow cannas because they presume the overwintering process requires heat and work. Keith reckons it is safer to lift them all. His preferred method is to lift the large clump of rhizomes after the foliage has been frosted in the light frosts we get up to Christmas. Then he breaks large clumps into two or three, potting them into largish, 10in pots. You can then overwinter them in any frost-free shed or greenhouse. Keep them just slightly moist.

If you try to store dry tubers, they will shrivel and growth will be curtailed the following spring. When the plants start to push up their red shoots in spring, bring them into a light place, water well and protect them from late frosts. By June, growth of the attractive foliage is well under way and they can be planted out to start to add momentum to the border.

Yellow streak virus is the biggest enemy of cannas. Carried by aphids, it produces yellow streaking on the foliage, which then becomes deformed. Destroy the infected plants and replant the following year with virus-free plants; the virus is not carried in the soil.

If you are thinking of new additions to your garden, there are three main groups of cannas, starting with the smaller ones which are 12 to 18in high. These are frequently grown from seed; anyone can do it, it’s easy-peasy.

They will germinate in about seven to 10 days and flower in about 100 days. Colours including red, white, salmon and yellow are readily available.

The mid-height group contains some show-stoppers such as Canna ‘En Avant’, which has yellow flowers with small red spots. I am about to order seeds of two species: Canna patens and C.warscewiczii. Both are shorter cannas with intense, dark pink-red flowers, the latter with green stems and leaves with red veining in them too.

The canna ‘Wyoming’, which belongs to the taller group (it can easily outstrip 6ft in favourable conditions), is also very striking with its strident dark purple foliage and apricot-orange flowers. The larger cannas cannot, however, be grown from seed.

The final favourite fact that I picked up about these amazing plants is that they were originally grown for food. Their ability to bulk up quickly means they produce starchy rhizomes in quantity, although these have now largely been replaced with yams as a food. Certain types of canna, though, are still grown for their starch, which is used in noodles and biscuits, and has a slightly aromatic flavour. The thick leaves are useful for thatching and wrapping things in for cooking.

Mine, however, will be left undisturbed to flower and flourish in my borders until the heavy frosts roll in.

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