Planting canna seeds

For those who have not grown Canna from seed before, this may be a good time to start giving it some thought. The best time to plant the seeds is dependant on the facilities that you have available.

If you have access to a propagator or heated greenhouse then seed can be sown as early as mid-January to early February. Given these conditions and reasonable weather in late spring and early summer we have sometimes had young seedlings burst into flower as early as mid-June.

If you are growing in a warm room, don't sow too early, unless you can provide heat and light to keep the young plants growing nicely through till April-May, when you will be able to transfer them to the unheated greenhouse, as they will likely be too tall for a cold frame.

Cannas have an extremely hard protective seed coat that is impermeable to water, so they will not germinate without some assistance. You can help the germination process by removing a bit of the seed coat through a process called scarification prior to planting.

Once canna seeds have been scarified, they are easy to grow. Only the tiniest amount needs to be exposed and it is better to file too little away than too much. If you look at the seed carefully, you will see a scar (hylem). It is through here that the growing shoot will break through. You should file the coat on the opposite side to the scar in order to avoid damage to the embryo.

How you go about scarification (nicking) is quite easy. There are several variations on this, and everybody develops their favourite method.

• Take a piece of sandpaper and sand the end of the seed until you get through the black seed coat.
• An alternative is holding them in a pair of pliers and using a file, carefully cutting into the coat until you reach the white endocarp within the seed.
• Or you may want to use a grinding wheel, which I use (a cheap Chinese import). I hold the seed in a pair of pliers and hold the seed to the grinding wheel just for a few seconds, until I see white.

Which ever method you use, you'll know that you're through when you see the white endosperm. Basically, what you're trying to do is make a hole in the seed coat so that water can get through.

Again, there are several techniques available to germinate the seed.

• I get some very warm water, almost hot and I put the seeds in for 48 hours or until I see the embryo coming out one end. I change the water twice daily to keep it from souring.
• Another popular approach is to add some vermiculite to a plastic bag, add water to moisten and then add the seeds. The bag is not locked so that air can circulate. The bag is kept in warm conditions, an incubatotor or airing cupboard. The disadvantage with this is that after a while the water will sour, and while I have used this method in the past I now prefer the first one, because changing the water requires a change of vermiculite as well, and vermiculite costs money!
• Some plant the seeds directly into small pots and water, waiting until a growth of some sort is seen, this might be a growing leaf or a white embryo, depending on the position the seed was placed in the pot. As some seeds will not germinate I always feel reluctant to spend on pot and compost until I see the seed has germinated. Call me a skinflint if you want, I just blame my parents!

Once you see the white embryo coming out you can pot them up. I use 2 inch peat pots filled with a peat-based compost with added fertilizer. I plant the seeds 1/2 inch deep with the embryo pointing downhill, water well and put in direct light.

Maintain a temperature of 21-24°C (70 to 75°F). In a few days (5-6) you should see growth. As the plants begin to actively grow, the soil will dry out quickly, so check daily and water when needed. Keep the growing medium moist, and do not over-water, as more seedlings die from that cause than from neglect.

Depending on how long a growing period the seedling has indoors it may need planting into a larger pot, and the advantage of the initial peat pot is that this just means planting the whole pot, thus no root disturbance.

Gradually harden off the cannas and transplant them outside, adding plenty of compost to the soil, following the last-frost date. They should flower about 90 to 120 days after the seed was sown.

Keep in mind that most cannas are hybrids bred for their flamboyant blooms and foliage. Seeds from hybrids will not come true to type, which means they will exhibit characteristics that are different from those of the mother plant (but not necessarily unattractive). If you're feeling a bit on the wild side and don't mind growing a few mystery plants, why not go ahead and start cannas from seed?

If you want exact clones of your canna plant, you'll need to propagate by division. The book The Gardeners Guide to Growing Cannas, by Ian Cooke (Timber Press, 2001), has excellent information on propagating cannas by seed and division, as well as information on cultivars and the history of cannas.

I would be interested in hearing about other techniques you might use.

Time for a second seed sowing

The first sowing of seeds is now in pots and growing away healthily, although we watch out every day for fungal growth. If any is spotted then we use a copper based solution to eliminate it.

So, now is the time for a second sowing and the picture below shows more batches of seed that have been scarified and now soak in warm water to encourage them to germinate and start the growth process.

The Canna seeds are soaking up the luxury of a hot spa, sorry no spray jets, in a heated incubator that keeps their daytime temperature at 25 degrees Centigrade. Here we are trying to persuade the scarified seeds to pop-out their first growth, see the picture below, so that we can extract it from the heated water environment and pot them up into something more conventional.

Above is a germinated Canna seed, showing the original scarification at the bottom, and the white embryo bursting out, by pushing open the trap-door (hylem) in the thick Canna seed shell. This is why, when I am scarifying the seed, if I can't identify where the trapdoor is located then I nick the seed on the side instead. Probably that is the best policy anyway.

Once the seed has germinated we insert it into a peat pot, filled with a peat-based compost with added nutrients and wait for the shoots to show above the soil level, as per the photograph below.

To illustrate what is happening with the seed below the surface of the soil in the pot, we have a photograph of a seedlings that we raised in a test tube, which shows all the "below ground" action taking place while we wait for that first shoot. With very special seeds we always grow them invitro, as we always feel more confident in getting a result in a test tube. However, it too expensive to use for several hundreds of seedlings each year.

Thinking about planting seeds

For those who have not grown Canna from seed before, this may be a good time to start giving it some thought. The best time to plant the seeds is dependant on the facilities that you have available.

If you have access to a propagator or heated greenhouse then seed can be sown as early as mid-January to early February. Given these conditions and reasonable weather in late spring and early summer we have sometimes had young seedlings burst into flower as early as mid-June.

If you are growing in a warm room, don't sow too early, unless you can provide heat and light to keep the young plants growing nicely through till April-May, when you will be able to transfer them to the unheated greenhouse, as they will likely be too tall for a cold frame.

Cannas have an extremely hard protective seed coat that is impermeable to water, so they will not germinate without some assistance. You can help the germination process by removing a bit of the seed coat through a process called scarification prior to planting.

Once canna seeds have been scarified, they are easy to grow. Only the tiniest amount needs to be exposed and it is better to file too little away than too much. If you look at the seed carefully, you will see a scar (hylem). It is through here that the growing shoot will break through. You should file the coat on the opposite side to the scar in order to avoid damage to the embryo.

How you go about scarification (nicking) is quite easy. There are several variations on this, and everybody develops their favourite method.

• Take a piece of sandpaper and sand the end of the seed until you get through the black seed coat.
• An alternative is holding them in a pair of pliers and using a file, carefully cutting into the coat until you reach the white endocarp within the seed.
• Or you may want to use a grinding wheel, which I use (a cheap Chinese import). I hold the seed in a pair of pliers and hold the seed to the grinding wheel just for a few seconds, until I see white.

Which ever method you use, you'll know that you're through when you see the white endosperm. Basically, what you're trying to do is make a hole in the seed coat so that water can get through.

Again, there are several techniques available to germinate the seed.

• I get some very warm water, almost hot and I put the seeds in for 48 hours or until I see the embryo coming out one end. I change the water twice daily to keep it from souring.
• Another popular approach is to add some vermiculite to a plastic bag, add water to moisten and then add the seeds. The bag is not locked so that air can circulate. The bag is kept in warm conditions, an incubatotor or airing cupboard. The disadvantage with this is that after a while the water will sour, and while I have used this method in the past I now prefer the first one, because changing the water requires a change of vermiculite as well, and vermiculite costs money!
• Some plant the seeds directly into small pots and water, waiting until a growth of some sort is seen, this might be a growing leaf or a white embryo, depending on the position the seed was placed in the pot. As some seeds will not germinate I always feel reluctant to spend on pot and compost until I see the seed has germinated. Call me a skinflint if you want, I just blame my parents!
  

Once you see the white embryo coming out you can pot them up. I use 2 inch peat pots filled with a peat-based compost with added fertilizer. I plant the seeds 1/2 inch deep with the embryo pointing downhill, water well and put in direct light.

Maintain a temperature of 21-24°C (70 to 75°F). In a few days (5-6) you should see growth. As the plants begin to actively grow, the soil will dry out quickly, so check daily and water when needed. Keep the growing medium moist, and do not over-water, as more seedlings die from that cause than from neglect.

Depending on how long a growing period the seedling has indoors it may need planting into a larger pot, and the advantage of the initial peat pot is that this just means planting the whole pot, thus no root disturbance.

Gradually harden off the cannas and transplant them outside, adding plenty of compost to the soil, following the last-frost date. They should flower about 90 to 120 days after the seed was sown.

Keep in mind that most cannas are hybrids bred for their flamboyant blooms and foliage. Seeds from hybrids will not come true to type, which means they will exhibit characteristics that are different from those of the mother plant (but not necessarily unattractive). If you're feeling a bit on the wild side and don't mind growing a few mystery plants, why not go ahead and start cannas from seed?

If you want exact clones of your canna plant, you'll need to propagate by division. The book The Gardeners Guide to Growing Cannas, by Ian Cooke (Timber Press, 2001), has excellent information on propagating cannas by seed and division, as well as information on cultivars and the history of cannas.

I would be interested in hearing about other techniques you might use.

Wot! No seeds?

Most years the first Canna seed are harvested mid-July, so it comes as a shock to realise that we are now almost at the end of August and the summer, and we have not yet had any seed ready to collect!

We still have many plants that have not yet flowered, but they are not naturally late flowering.

The only conclusion is, that once again, the non-seasonal rain patterns and cloudy conditions have not supplied the Cannas with the energy they need to grow their flowers and subsequent seeds.

We are hoping for a bit of an Indian summer to give us some pleasure from all the hard work involved in growing the Collection, but we have little faith that will happen.

Hibernation of Canna seed

Cannas are unique in many ways, one of them being that they are the only member of the the Liliopsida Class (monocot family) in which hibernation of seed is known to occur, due to its hard, impenetrable seed covering.

Seed hibernation, is different from seed dormancy. Seed dormancy can be defined as a seed not germinating when conditions, e.g. light, water/nutrient availability or the presence of activating substances like smoke, are favourable. While, hibernation is the ability of a seed to remain in hibernation when there is a lack of things essential to their development (water, sunlight, nutrients, etc.) or in harsh conditions (extreme cold, extreme heat, hard ground, etc.). There is not a specific time limit in which a seed may hibernate; some seeds found in the arctic grew after an estimated 10,000 years. When conditions are right for the particular type of seed, they can come out of hibernation and grow.

We have a famous instance of Canna compacta seed that was discovered by archeologists in an Inca rubbish tip, and subsequently germinated! See left. I have never been able to trace anybody with any personal knowledge of that well-documented experience, and the fact that the plant grown from it has been lost to us is a cause of frustration.

Seeds display hibernation for very short periods of time every year. In autumn, seeds produced in summer may have a chance to grow while the soil is still warm, but instead do not grow until spring. The seeds have chemicals encoded into them that will not allow them to germinate until the soil warms up again, a sign of spring. This is called after ripening.

Seeds may also go into hibernation for other causes. Many pines have adapted to forest fires that destroy trees by creating pine cones that open in extreme heat (fire) and release seeds coated with a material that will break down only in extreme heat. The seeds hibernate until this happens.

Canna seeds have a hard coating that must be broken down by contact with rough rock, soil, etc. before they begin to grow. Until the shell is broken and water reaches the seed, the seed remains dormant.

When released, some seeds (especially those in a desert environment) must wait for rain before the seed is triggered out of hibernation and begins to grow. There are many other causes of dormancy. It is an unclear phenomenon; the limits of seed hibernation are still unknown, and many triggers have yet to be discovered.

Growing Cannas from Seed

A posting by Keith Hayward on the International Canna Group

For those of us in the northern hemisphere, now is the time to sow seeds for flowers this year. Here are a few pointers for those who've never done it before.

Canna seeds have a very hard and impermeable coat, and you can't just bury them in compost and expect them to grow. The chances are that nothing would happen.

You have to scarify them. But this is not as easy as it sounds. It truly is an engineering job, requiring engineering equipment if you are to make any impression on the hard seed surface.

I use an engineers file and a pair of engineers pliers. I grip the seed in the pliers, and wipe it several times across the file until the white interior of the seed just shows through at one place.

Then I bury the seed to a depth of about 1 cm in peat-based seed compost. I soak the compost in water, and enclose the whole seed tray in a polythene bag, and then place the whole thing in a propagator at 80F (30C).

Done this way, germination is very quick. The first shoot usually comes through in about 7 days, and most are up after about 10 days. Germination rate is very good, 70% to 100%.

I find that pre-soaking the seed makes no difference to the speed of germination. What is important is the humidity and the germination temperature. The great danger to seedlings is damping-off, which happens more at lower temperatures. Also, canna seedlings will not tolerate being dried out.

Other people may have other techniques - let's hear them.


The photo shows C. tuerckheimi sown on 22 January 08. Tuerck is a particularly fast mover and the first shoot came through in 4 days! The photos were taken 31st January. Germination was very good, and they are growing well.

Also shown are seedlings of Tropical Rose about 2 weeks from sowing the seed. Seeds of the Tropical Series will flower in 100 days from sowing the seeds, so you can sow them in March and still have them in flower in summer. They come in 5 colours: Rose, Yellow, Red, White, Salmon. The Tropical series are pre-scarified, and germinate in 7 to 10 days. If anyone would like to try them but can't find the seed, then we will post it anywhere worldwide.

See website www.hartcanna.com/seeds.htm

Keith Hayward

Farnborough, England

Helping the pollinators

We have not had a good seed harvest this year, and we have automatically blamed the terrible summer we have endured. However, even if we have flowers in bloom we still need pollinators to assist when we are not there! Are we doing enough to ensure that we get enough bumblebees living by the collection? We have started planning ahead for next year to try and ensure we maximise natures natural pollinators.

Bees need flowers for sustenance, and our Cannas need bees for pollination. But it's important all the flowers we grow, not only cannas, provide the food that bees need. It's vital that we provide flowers throughout the bumblebee's life-cycle, straight through from March to September. Here in the temperate north, cannas start their flowering season in June, carrying on flowering until the frosts arrive, normally late October or early November, so that provides the goodies from early summer onwards. So, as canna growers, our gardens also need to provide flowers that will supply them with food from March through to June, when the Cannas kick-in.

The old Foliage Group varieties are particularly favoured by natures pollinators

So, the secret will be to try and keep continuous flowering, and it's also a good idea to have at least two nectar- or pollen-rich plants in flower at any one time during this spring period. The nectar feeds the adult bee, while the pollen is collected to feed the young. Of course, the more flowers you have, the more attractive your garden is to bees, so you can never have too many!

Most double flowers, especially modern roses, are of little use, because they're too elaborate. Some are bred without male and female parts, while others have so many petals bees can't get to the nectar and pollen to collect it. This is the main reason why Cannas are popular with many bees. So for spring we will have bluebell, daffodil, flowering cherry, forget-me-not, lavender, lily-of-the-valley, rhododendron, rosemary, viburnum, and thrift. For the early summer we have the early Cannas, fennel, lavender, passion flowers, thyme and vines, and then onwards there are always several hundred canna flowers open at once, so that should do the trick.

Let you know how we get on next year...

Hanging in there

It is October 24th, 2007. The weather forecasts have told us that frosts will have hit us already. Speaking on the telephone to Keith Hayward at Hart Canna (the National Canna Collection) we learn that they have already been hit by frost and have moved the collection indoors, and they are 150 miles south of us!


Here, in Worcester, we are hanging on. The tender species get zapped at 3-4 degrees centigrade and they are now safely in the poly tunnel in the background, safely ensconced for the winter. The photograph above was taken today at noon. It shows that we are still hanging in there, trying to get as much mature seed as we can. We have over a hundred cultivars that have fruit that it is not yet ripe seed. So, we are hoping for more of the final ripening of seed.


The lack of flowers over the summer, due to 2 months of continuous rain and little direct light, meant that we had few flowers, and therefore little seed. This year has been our worst year ever for seed. We may be begging seed shortly from our Canna friends around the world! In the meantime we are waiting expectantly, as long as the overnight temperatures allow.