Dahlias in Containers
 

I have just started some large dahlia tubers, and I'm trying to figure out where I should put them. My raised beds are only two feet wide and about 8 inches deep, not big enough for these monsters I thought.

I have several containers 15" deep and 24" across, would I be able to plant one tuber per container? I have been scouring the internet for hours but all the information out there seems to be for smaller cultivars. The varieties I bought will be 4' high and the blooms are 11" across or so. I have a sturdy support system but I want to make sure they have all the space they need for proper development.

Good plan? Or should I find some other way of planting them?

I'd be interested in which dahlias you've chosen. A dear friend of mine was Edna Comstock, whose husband bred and named for her a very well known dahlia called the Edna C.

I had to look that up, what a beautiful flower. I bought four tubers each of Cafe au Lait, Penhill Watermelon, and Walter Hardisty.

Do you think I should keep it at one tuber per container?

[QUOTE=SuntannedSwede;632401]I had to look that up, what a beautiful flower. I bought four tubers each of Cafe au Lait, Penhill Watermelon, and Walter Hardisty.

Do you think I should keep it at one tuber per container?[/QUOTE]

Only Walter Hardisty is over 10" across (AA). It is a beautiful white - grew it for many years in a better climate than where I currently am. Penhill Watermelon is a great variety too. Enjoy.

Cafe au Liat - B - Informal Decorative
Penhill Watermelon - A - Semi-Cactus
Walter Hardisty - AA - Informal Decorative

Good to know, thank you. Would you allow one tuber per container, or would it be acceptable to double up? Assuming heavy feedings of liquid fertilizers

I don't know anything about dahlia culture. It's one of those "someday" things I still haven't done. I'd love to see pictures when yours are blooming.

[QUOTE=SuntannedSwede;632422]Good to know, thank you. Would you allow one tuber per container, or would it be acceptable to double up? Assuming heavy feedings of liquid fertilizers[/QUOTE]

Recommended spacing for AA varieties is 18" so your call. They are heavy feeders so I work in a half handfull of granluar 6-12-12 or 10-10-10 when I plant them, and a second dressing of the same somewhere between mid-July & mid-August. Keep the fertilizer away from the stem to avoid burning the plant.

Where I live now I have a hard time flowering AAs (10"+) due to our short season but I always try a few - this year my AAs will be AC Darkhorse, Bonaventure, Clara Huston, Holland Festival, Kelvin Floodlight & Purple Taiheijo. I start the AAs & As indoors in pots (right about now) before planting them out in early/mid June. Typically the smaller the flowers, the earlier they bloom so choose your flower sizes a accordingly. I tend towards `B' (medium, 6"-8") here in Zone 3a since they always flower, unless decimated by hail.

The dahlias I am familiar with would need to be lifted and stored in your growing zone if you want to replant them next season. I wonder if you could overwinter them in containers in your garage.

- Lisa

[QUOTE=greenthumbomaha;632442]The dahlias I am familiar with would need to be lifted and stored in your growing zone if you want to replant them next season. I wonder if you could overwinter them in containers in your garage.

- Lisa[/QUOTE]

They all need to be lifted for winter storage in colder climates - Dahlias originated in Mexico, and any frost will immediately kill the foliage to the ground, and if your soil freezes, the tubers will die. I certainly can't overwinter them here in my garage (Zone 3a), but folks in better climates should be able to. I store mine in the coolest room in the basement, right on the floor. They need to be stored between 4 and 8 degress Celcius or else they will sprout.

I think you are fine for the first year anyways, as you only have a single tuber of each variety. Your pots should be big enough. You'll get an idea in the fall how many more tubers each plant developed and then the decision for next year would be piece of cake :). Several tubers in one pot for more branches, or single ones in more pots. I like to plant several tubers of the same variety in one spot for a better show.

Hope it helps. Happy Gardening!

+1 on one per container. They will grow large and multiply. Next year you will be trying to find friends to give homes to all the splits. :yes: Almost floral zucchini!

Thank you guys for the help- I have set aside enough pots for all of the tubers, only have 3 that are sprouting though.

Much appreciated

they will need lots of water, fertilizer and support like a big tomato plant. three good stakes placed around them and then some string to hold the branching plant adding more string as they grow.they are very large plants and the blooms are heavy. I like growing them in pots but they take a fair bit of work. worth it for the gorgeous blooms.
KarenO

Good to know Karen- I was wondering about how many stakes I would really need

I'm looking forward to pictures! Of the plants and their blooms.

Hi Deborah! I'm sorry to have taken so long to give an update. I ended up placing the Walter Hardisty's in the raised bed, and got a lot of blooms considering the shallowness of the bed. I fed regularly with Miracle Gro, I think that's the only reason we had any flowers. I have attached picture of the few large blooms we had, I didn't now the plants would produce several, smaller heads, under 'tougher' conditions but there were a few.

[QUOTE=SuntannedSwede;668853]the Walter Hardisty's [/QUOTE]

Walter H. is a very beautiful white, but typically a later variety. Since it looks like you are Zone 3a like I am, do consider Verda since it flowers earlier.

[url]http://www.sidsdahlias.com/images/Verda.jpg[/url]

[QUOTE=RJGlew;668884]Walter H. is a very beautiful white, but typically a later variety. Since it looks like you are Zone 3a like I am, do consider Verda since it flowers earlier.

[URL]http://www.sidsdahlias.com/images/Verda.jpg[/URL][/QUOTE]

Hey thanks for the heads up- Verda looks like a beautiful dahlia. I definitely like the idea of earlier blooms. Much appreciated!

Those look great! When is your average frost date? (Written sitting in Philadelphia where it currently is rainy and warm - almost 70F! on October 24th!). My dahlias seem to have wound down for the season after a hot and dry Sept but I am still getting a trickle of blooms.

[QUOTE=PhilaGardener;669078]Those look great! When is your average frost date? (Written sitting in Philadelphia where it currently is rainy and warm - almost 70F! on October 24th!). My dahlias seem to have wound down for the season after a hot and dry Sept but I am still getting a trickle of blooms.[/QUOTE]

Thank you! Sorry I should clarify- these photos were taken a few weeks ago, according to the Ag gov't site our first frost typically occurs during the second week of September, but we were lucky this year. I think the first real freeze we had was in the first week of October, maybe a little later. Wow- sounds like winter is taking its sweet time down in Philadelphia! All my tubers have been tucked away already!

The new term apparently is "hotumn", although I think that is a recent invention of the media.
[URL]https://www.nytimes.com/2017/10/24/nyregion/warm-autumn-weather.html[/URL]

We had one cold morning dip in to the upper 30s but so far the cold seems to be staying away. I'll probably lift my dahlias this weekend. Winter will get here eventually, won't it? :twisted:

I have one dahlia left over from my flowers this summer. It wins the persistence award, as it is still blooming months after being planted. It is in a small pot, and only got osmocote, but is really pretty at the moment.

Is taking cuttings the best way to propagate it? Digging up the roots to propagate is for in-ground plants, right? I am thinking it would work with a container plant, but probably not be the best way.

If you knock that out of the pot and examine, you will find it has formed tubers. Either trim the top, shake the mix off and store the tubers in a paper bag over the winter or set the pot on its side under a bench and let it dry out and go dormant (like one would do with a tuberous begonia).

If you want to increase this clone, you can divide the tuber mass but make sure each tuber retains a bit of the stem base as that is where the new shoots form. You can also take cuttings, but I think you will have the greatest success doing so when the plant starts to regrow at the beginning of the growing season rather than now when it is winding down into dormancy.

Thanks for the help. Here's a pic of my plant:

They sure look great! I bought several of those earlier in the season as well, some with purple edges.

They are so susceptible to mild dew in my area, even in the heat of summer I only have a couple of survivors now, but they haven't been blooming for a while as they most their leaves to the molds. They produce tons of blooms if they don't get diseased.

[QUOTE=Cole_Robbie;669405]Thanks for the help. Here's a pic of my plant:[/QUOTE]

[QUOTE=Cole_Robbie;669405]Thanks for the help. Here's a pic of my plant:[/QUOTE]

I left that plant outside too late in the fall, and the frost got it. I took it inside and forgot about it. Two months later, green shoots were coming out of the root ball. I re-potted it, took it to the greenhouse, and my 2017 dahlia looks to be doing well.

The plant got a little freeze-nipped, but it is blooming again.

Gorgeous! What is the name of that cultivar?

Nan

Thanks. It is out of the 'Harlequin Mix,' seeds from Harris.

[url]https://www.harrisseeds.com/products/20271-dahlia-harlequin-mix[/url]

Lovely flower. I am so glad that you saved this one over. Most people just dispose of these beauties. Next year be sure to divide the roots or you may not be successful in saving it over.