Saturday, February 19, 2011

Starting cannas from seed

Cannas produce copious amounts of seeds that are rounded, dark brown to black in color, and heavy enough to sink in water. Since they resemble shotgun pellets (and could possibly be used as that, considering how hard they are), cannas are sometimes called “Indian shot”.

Canna seeds have a very tough protective coat, presumably to allow them to survive until the next rainy season arrives. To speed up germination, various methods have been proposed. They all involve cutting, clipping, or nicking the seed coat—a method called scarification in horticultural jargon. This allows water to penetrate the seed in order to trigger germination.

After trying various techniques involving nail clippers and emery boards, I’ve settled on the following procedure. I’ve used it successfully in past years to germinate several species of canna. This year I’m trying it on the banana canna (Canna musifolia), one of the tallest species (up to 8 ft.) with possibly the largest leaves of any in this genus. In fact, the leaves strongly resemble bananas, hence the common name.

110213_canna_seeds_step1a
Just a few of the canna seeds I collected last fall.
110213_canna_seeds_step1b
Step 1: Nick the seed coat using a Dremel rotary tool. After trying a nail, ice pick, nail clipper, etc., I decided to switch to a Dremel (which we use to file down the dog’s nails) because the seed coat really
is that hard to penetrate.
 
110213_canna_seeds_step2b
Nicked seed coat—I probably took off a bit too much;
just a tiny nick is needed
110213_canna_seeds_step2c
Step 2: Put the nicked seeds in a glass of warm water (almost hot) for 48 hours. Replace the water twice a day so it doesn’t go sour.
 
110213_canna_seeds_step3
Step 3: Stick the seeds in growing medium and keep it moist
(but not soggy). Keep in a relatively warm place with direct light. The experts call for 70-75°F, but it’s never that warm in our house and it doesn’t seem to matter too much.

Everybody has their own preferred seed growing medium and technique, so by all means, use what works for you. I simply stuck my seeds in small cactus pots filled with a coarse potting mix. I keep it moist by spraying it with a spray bottle. You should see growth in as little as 5 days.
100918_cannas
Here are some cannas in our front yard, in the back behind the banana (left), lemon tree (middle) and bamboo (right). Their leaves add a tropical flair, and their flowers are hummingbird magnets.
 
 

6 comments:

  1. Nice post! How large will a canna get its first year from seed? Will it flower? I know cannas are pretty simple to grow and do well here -- I see them all over even here in St. Louis -- but I've never tried them before. Perhaps I will this year...

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  2. Alan, cannas are very simple to grow. They only need two things: lots of heat, and a fair amount of water, at least until they're established.

    If you start the seeds early enough (like now), I believe you can get it to grow to 5 ft in the first year--depending on the species, of course, since some of them are shorter.

    If you want, I can send you some seeds of a variety that bloomed forever last year. Gotta go back to my records to figure out which one it was. I also have a small Tropicanna offset potted up for you.

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  3. Thanks for that great information Gerhard. I've never thought of growing them from seed. I usually just divide the roots. Will have to give it a try and see what happens.

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  4. Missy, dividing the rhizomes is the easiest way and gives you much more substantial plants to start out with. However, sometimes you can't get rhizomes of a variety you'd like to try, so starting from seeds is the way to go.

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  5. Great post Gerhard! I've too have grown Cannas from seed before. I scarify them using one of those cheap peeling knife (the sort that doesn't need sharpening) but your method looks less dangerous :) I've tried them without scarification before, takes 2-3 weeks longer to germinate.

    About 4 years ago all our Cannas were infected by the Canna Mosaic Virus and we had to dig out and bin all of them. And for years nearly all of the Cannas you can buy here were infected. The only way you can be assured that the Canna you have in the garden is virus free is to grow them from seed. The only problem is that you're limited to species cannas as cultivars don't come true from seed and can only be propped by rhizome division.

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  6. Mark and Gaz, if I used a peeling knife to scarify cannas, a trip to the emergency room would be in order :-).

    Karchesky Canna is a good place for seed if you ever need any.

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