Louis Raymond experiments in his own gardens like

a mad scientist, searching out plants that most people have

never seen before & figuring out how to make them perform.- The Boston Globe

…Louis Raymond ensures that trees can grow in Brooklyn…

or just about any other place where concrete consumes

the dirt and skyscrapers shield the sunshine.- USA Today

 
 

NEW Trips to Take!

Myrtle's easy when the conditions are right.

 
 
 
 

NEW Plants to Try!

Louis tries to capture the exact words to describe the fleeting but deep pleasures to be found in these Summer-into-Autumn incredibles.

 
 
 
 

New Gardening to Do!

Allergic to bees? You can still have an exciting garden, full of flowers and color and wildlife.

 
 
 
 

Plant Profiles

Cannas: Colorful Even Underground.

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Am I growing too many kinds of cannas, yet?  I'm always tempted to grow more, because then I get to dig up more.  Cannas are so generous in their display that even what's underground is colorful. 

 

Canna plants vary enormously in height as well as coloring.  And unlike, say, dahlias, where the tubers are always that same tan, bigger or smaller, no matter what color the flowers are, or how big the plants can get, canna rhizomes are a show in themselves.

 

This is a small species, Canna paniculata, with bulb-like rhizomes barely bigger than shallots.  The plant gets two feet tall, making it a dwarf in the canna world.

 

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The pure white rhizomes are typical of cannas whose foliage is plain green. 

 

What a difference are the pink tubers in the picture, below.  It's a purple-leaved canna cultivar, 'Pacific Beauty'.

 

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'Pacific Beauty' also shows the rounded turnip-like habit of cannas that prefer to grow in regular garden soil.  Some other cannas are happy to grow in water if given the opportunity, and their rhizomes are longer and, comparatively, thinner.  Look at the ropey roots of 'Sweet Heart' in the picture below.  If I'd had an earth-bottom pond, those rhizomes would have quickly nosed many feet through the mucky soil.  (See "How to handle it" below for strategies for the cannas that can be grown in water.)

 

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In the picture below the rhizomes are long and ropey—but now have a pink blush.  This must be a purple-leaved aquatic.  And, indeed, it's 'Intrigue'.  As is usual for aquatic cannas, its foliage is narrow and almost spear-like.  Cannas that grow only in regular garden soil tend to have leaves so wide they look just like those of bananas.

 

canna-intrigue-640

 

Round and turnip-like white rhizomes in the crate below: This one below must be a green-leaved "terrestrial."  Indeed, it's the giant green-leaved species, C. altensteinii, which can grow to twelve feet. 

 

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Looking closer, though, there's a surprise:  A pink turnip amid the white ones.  Is this a mutant?  Will it sprout a purple-leaved stem?  Is this a never-before-seen C. altensteinii 'Purpurea'? 

 

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We'll know next Summer, when all the cannas get replanted in the garden.  Stay tuned!

 

 

Here's how to grow these exciting tropical perennials:

Latin Name

Canna cultivars

Common Name

Canna

Family

Cannaceae, the Canna family.

What kind of plant is it

Rhizomatous perennial.

Hardiness

Zones 8 - 11

Habit

Clumping and erect, with thick canes sheathed in banana-like foliage and topped by flower clusters.  Aquatic varieties have long and comparatively thin rhizomes, with much more space between the vertical canes.  So they can develop quickly into wide-spread colonies.  Terrestrial varieties tend to have much thicker rhizomes, with closely-spaced stems.  Their colonies don't increase as quickly, but are much denser.

Rate of Growth

Fast when the necessary water, rich soil, and heat are present.

Size in four months

Like dahlias, cannas usually mature to full height, and respectable colony size overall, in one season, regardless of the size of the starter rhizome.  Dimensions vary with the species and cultivar.  See "Variants" below.

Texture

Lush, energetic, and tropical.  Cannas are too vigorous, their shoots too numerous, and their banana-like foliage too large, for clumps to be seen through.  The jostling and, often, people-high leaves bring an iconic hot-climate vibe. 

Grown for

the foliage!  See "Variants" below.  Canna foliage can be huge or (comparatively) small, narrow or wide, green or any of a scary range of solid colors, variegational patterns, colorful edges, and metallic "overlay" blushes—or several of these options at once.  Want a variegated leaf that also has a colorful edge as well as a metallic overlay?  If there isn't a canna with foliage like that already, there will be soon.

 

the flowers!  See "Variants" below.  Canna species have smaller but usually brilliantly-colorful flowers known, conveniently, as species-type flowers.  Canna hybrids have been bred for larger and larger flowers, in dense and often (at least to my eye) congested and tacky clusters.  Those are the hybrid-type flowers.  Species flowers are considered tasteful and cool by sophisticates, who in turn sneer at the dense and bright clusters of hybrid flowers.  Species flowers, in turn, are dismissed by fans of the hybrid flowers because they're tiny as well as out of proportion to the (usually) huge plants that produce them.  Which is true.  But cannas as an entire race are beyond the pale for many gardeners of fastidious (or, as I might say, limited) aesthetics, so growing just the species-flowered varieties won't ingratiate you with them one bit.  My own pathway through this taste and class minefield has been to grow plenty of cannas with species flowers—which, in any event, I'm authentically jazzed about—and to plant the hybrids with either winking irony or a defiant embrace.  I wouldn't be without 'Pacific Beauty' or 'Pretoria' or 'Ehemanii', but neither would I forgo C. altensteinii or C. glauca.

 

their ease of overwintering:  Compared to dahlia tubers, canna rhizomes are tough and tolerant even when snoozing for five or six months in the basement.  That said, survival until Spring can't just be assumed.  See "How to handle it" for strategies on overwintering.

Flowering season

Year-round, if your climate is warm enough.  Otherwise, mid-Summer to frost.  See "How to handle it" for some cautions on trying to bring cannas into bloom earlier in the season.

Color combinations

With so many choices—see "Variants" below—there's a canna for every possible color scheme, from the most iconoclastic and hedonistic to the most restricted and virginal.

Partner plants

Cannas' large and often paddle-shaped foliage, easy lushness, and strong vertical habit are perhaps the ultimate occasion to bring in partners with ferny or grassy or small leaves in as strong a contrast to the canna's foliage color and shape as you can find (or tolerate).  Ferns of any sort, ornamental grasses, the thin-caned Fargesia bamboos, small-leaved evergreens such as box or yew or holly?  Bring them on!  If your cannas are towards the front of beds, or in large containers, plant low and cascading partners in front: Asparagus fern, ivy, or sweet potatoes.  Allow room for the canna clump's expected spread during the hot months, so it won't just roll right over smaller "frontage" plants that are, by August, hard by its newly-arising canes.

Where to use it in your garden

In large planters, in pots sunk in water gardens (see "Quirks or Special Cases" below), at the back of the a bed that needs to look better and better from July to frost.  Dwarf varieties can be right at the front of beds.

Culture

Full sun, rich soil, and heat.  Cannas will burgeon year-round if your weather's warm enough, and even in cold climates will produce new canes steadily until frost finally brings things to a halt.  Some cannas are also happy to grow in pots sitting in, or even slightly submerged in, water, but there are no cannas that require an aquatic setting. 

How to handle it: The Basics

Plant in Spring, after the soil's warm.  If it's not yet time to plant your tomatoes, it isn't time to plant your cannas, either. 

 

Canna rhizomes need to be planted only a couple of inches deep.  They'll grow deeper on their own if they want to.  As with dahlias, it isn't necessary to water right after planting; let the rhizomes wake up and announce their intention to join the Summer party by showing above-ground sprouts first.  Also, Spring is usually wet enough on its own.

 

Cannas need little attention as they're growing in June and July.  They're self-supporting, too.  Flowering begins by August, and you may want to groom the flower clusters every couple of days to pull off spent blooms.  (Some varieties are better at being "self-cleaning," as it's called.)  Unless you have one of the varieties where the seeds themselves are showy, such as 'Striped Beauty', cut spent flower stalks off as far down as the top leaf of the stem.

 

As Fall gathers force, let your cannas get hit by frost, so the canes are very substantially killed back.  As long as the rhizomes themselves don't freeze, the plant is fine.  Compared to dahlias, canna clumps are easy to dig up:  Just stomp your shovel down to the hilt and start angling back to lift the clump up.  Cut off the spent foliage a few inches above the soil level; it's a bit gross in its floppy dampness, so you'll probably want to wear gloves.  Get most of the soil off the clump, even if you have to drop it back to the ground, or even throw it to the ground.  Larger varieties can have clumps that are almost too heavy to lift, so make it easier on yourself by slimming them down.  With the major exception of the aquatic cannas (see below), there's no worry about damaging the rhizomes through rough handling.  If clumps split apart, it's almost to the better: They're that much easier to store.

 

Leave the rhizomes outside in the sun for a few days to help them dry out even more.  I overwinter mine in black plastic crates that retail nurseries are usually thrilled to be able to give away.  But don't forget to hustle the rhizomes into a cool and frost-free spot in time.

 

Cannas are typically easy-keepers, at least compared to dahlias.  But check on them every month or so—especially the aquatics—to see if any are rotting or shrivelling.  It can be helpful to store the aquatics in a dry medium, like bark mulch or styrofoam peanuts or the wood-shaving packing material known as excelsior, any of which will cut down on evaporation without also encouraging rot.

 

If you have the room, bring the rhizomes into heat and light a couple of weeks before you're intending to plant them in the Spring.  They'll normally be happy to start sprouting ahead of time.  Then it's all the easier to gently pull rhizomes apart to separate any portions that might have rotted, or just to make up the number of individual clumps-to-be you need.  When the soil's warmed up and the days really feel like Summer's near, plant the rhizomes.  As with dahlias and tomatoes, there's nothing gained by planting too early, when the weather's chilly and wet.  Cannas need heat to get going in the Spring, and would rather wait to be planted out later, even if that means they'll still just be bare-root rhizomes.  They'll still be bigger clumps by August than the rhizomes planted when Spring was still chilly.

How to handle it: Another option—or two?

Cannas grow as well in large containers as they do in-ground.  As long as they get the water, heat, and sun they need, they don't mind being pot-bound.  Their self-supporting height and, often, sensational color in both foliage and flower, can bring both architectural prominence as well as sizzling and even avant-garde energy to large containers.

 

Because cannas typically reach full height and bulk in August and September, though, I don't worry about potting them up in early Spring just to be able to place active plants in the gardens in May instead of just-sprouting rhizomes.  But cannas are equal-opportunity growers, so if you have the space in a greenhouse or on a windowsill that's warm enough and sunny enough, pot away.

 

Practically speaking, however, most greenhouses are full-to-bursting by March and April already, mine included.  So I'm happy not to be trying to squeeze in a few dozen more pots in for those last six or eight weeks before Spring planting.  Plus, having cannas (or dahlias, for that matter) going full-tilt by early July makes it easier and even inevitable not to be thinking about the other plants that could be making the July gardens a wonderland in their own right.  For me, waiting to enjoying cannas at their August-to-frost peak means that I'm still taking full advantage of the other plants whose peak is July into August.

Any quirks or special cases?

Some cannas are happy to grow in very wet ground, or even submerged a few inches in a water garden, but none require an aquatic habitat if their soil is rich and they get watered during droughts.  I grow cannas aquatically just because they tend to grow faster (which makes sense: they've got all the water they could possibly need), and then I don't have to worry as much about watering them.

 

Aquatic cannas typically have longer and thinner rhizomes and, sometimes but not always, foliage that's narrower and spear-like, instead of the wider and banana-like foliage of the terrestrials.  But even canna vendors can sometimes be unsure if a given canna can grow aquatically.  Divide your clump (see "Progatation" below) or buy two starter rhizomes, and see which does better, the one in the water garden or the one in regular soil.

 

Aquatic cannas almost never need to be planted in-ground, even if your water garden is earth-bottomed and you're gardening where cannas are hardy.  Growing in pots, they send out roots into the water from the top of the pot and out through the holes in the bottom, and so "feel" like they're growing almost free-range anyway.  Also remember that it's a messy business, indeed, to try to dig up canna clumps from the bottom of an earthen pond; much simpler to lift out a pot.

 

Aquatic cannas are trickier to overwinter than terrestrial ones.  They may crave all possible water during the warm months, but they need to be stored a bit drier than usual during the cold months.  Because they're long and comparatively thin, there's that much more surface area that can be the entry point for the fungus and bacteria that can rot them.  Worse, the long rhizomes break much more easily than those of terrestrial cannas, whose rhizomes can be as thick and as woody as turnips.  If you grew your aquatic clumps aquatically, they'll be in pots.  Unpot them and try to remove all the soil you can.  If you grew your aquatics terrestrially, dig them up more gently than you did up the terrestrials.  Gently remove the soil you can with your fingers and some modest shaking.  You could even dunk them in a tub of water and swish them around to help loosen even more soil. 

 

Leave the rhizomes outside in the sun for a few days to help them dry out even more.  I overwinter mine in black plastic crates that retail nurseries are usually thrilled to be able to give away.  But don't forget to hustle the rhizomes into a cool and frost-free spot in time.

 

Check on the rhizomes  every month or so to see if any are rotting or shrivelling.  It can be helpful to store aquatics in a dry medium, like bark mulch or styrofoam peanuts or the wood-shaving packing material known as excelsior, any of which will cut down on evaporation without also encouraging rot.

 

If you have the room, bring the rhizomes into heat and light a couple of weeks before you're intending to plant them in the Spring.  They'll normally be happy to start sprouting ahead of time.  Then it's all the easier to gently pull rhizomes apart to separate any portions that might have rotted, or just to make up the number of individual clumps-to-be you need.  When the soil's warmed up and the days really feel like Summer's near, plant the rhizomes.  As with dahlias and tomatoes, there's nothing gained by planting too early, when the weather's chilly and wet.  Cannas need heat to get going in the Spring, and would rather wait to be planted out later, even if that means they'll still just be bare-root rhizomes.  They'll still be bigger clumps by August than the rhizomes planted when Spring was still chilly.

Downsides

Despite their tropical origins, cannas are difficult to grow in the tropics because of a nocturnal beetle that can defoliate the plants.  Yes, you can control it, but that means either nightly visits to your cannas to remove it, or some nasty chemicals.  In the tropics, there's never a shortage of options for huge and banana-like foliage: Besides the true bananas, there are hundreds of choices amond the gingers and philodendrons and arums and palms.

 

Cannas are much easier, then, when grown outdoors during the warm months of colder climates, or in mild Mediterranean-type climates, where that nocturnal beetle isn't a problem. 

 

Japanese beetles, though, can sometimes take a serious shine to the foliage, and there can be caterpillars to fend off, too.  If you garden where cannas can stay in-ground through the Winter (warm Zone 7 and south), voles can munch through the dormant rhizomes, too.

 

All of these scary scenarios notwithstanding, cannas are among the easiest of tropicals to grow anywhere BUT the tropics, as long as they can get at least six hours of sunlight.  Here in Rhode Island, with the exception of an occasional Japanese beetle, my many cannas get no warm-weather damage from insects or critters.   

Variants

Cannas come in a dizzying range, with a couple of hundred hybrids now available and more arriving on the market annually.  There are also about twenty species, many of which are also quite garden-worthy.  

 

Cannas are diverse across all possible metrics:  overall height (from two feet to over fifteen); preferred habitat (terrestrial-only, or also happy to grow in bog-like ground or even in shallow waters); leaf shape (narrow to totally banana-like); leaf size (a foot or two to six feet and more); leaf color (solids in green, blue, reddish, purple, or mahogany, plus all kinds of variegationals with yellow stripes or a purple "underlay" or a pewter "overlay" or a purple edge, or several tricks at once); bloom type (smaller species flowers and larger hybrid flowers); bloom color (near-white to yellow to pink to orange to red, often with bicolor effects, either petals of different colors or colorful spots; there are no flowers that are purple or blue, so roses, iris, orchids, and dahlias still hold the joint crown for broadest range of colors); flower "self-cleanability" (some cannas are better at others than shedding their spent flowers); flower angle of display (most are held fairly upright atop spear-like stems, but a few cannas have flower sprays that arc instead of spear, and at least one, Ehemanii, has individual flowers that dangle seductively); seeds (some of which can be as colorful in display as the flowers they arose from)—and, as we've seen today, rhizome shapes and colors.

 

You can usually find a canna that, in itself, is diverse across more than one measure.  Want a canna that's got purple as well as narrow foliage, species flowers, and can grow aquatically or terrestrially?  'Intrigue' is for you.  One with green leaves with yellow stripes, plus showy seeds?  'Striped Beauty'.  Purple leaves with a pewter overlay and—trumpets, please—flowers that are yellow instead of the usual (for cannas with purple leaves and pewter overlay, that is) apricot?  'Pewter Moon'.  Tiny and green-leaved, with small but brilliant red-and-yellow flowers?  Canna paniculata.  Huge and green-leaved, with small but brilliant red-and-orange flowers?  Canna altensteinii.  Same huge height and green leaves, but with all-red flowers?  'Hummerhaven'.

Availability

On-line andat retailers; only the most popular (which you can also interpret as the most "common") cultivars are typically sold retail.  On-line vendors are where the latest and most unusual cannas are.  I'm very partial to Karchesky Cannas, but you'll find cannas for sale all over the web. 

Propagation

By division of the clumps.  If you're dividing a clump that's growing in the ground, first lift the entire clump with a shovel or fork.  You'll more likely find that it will separate easily into daughter clumps.  If necessary, gently pull segments to free them from the mass.  Species cannas can also be grown from seed. 

Native habitat

Cannas are all native to the New World, from Mexico and the Caribbean to northern Argentina.  They are an important ornamental as well as agricultural crop world-wide.

 
 
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