Has anyone grown their dahlias in containers as a regular practice?

There are several posts in the Dahlia forum on this subject. Growing dahlias in pots can be very tricky. Growing in pots magnifies all of the gardener's mistakes. I do not grow in pots but have in the past. What deterred me was the constant watering in warm weather, twice a day in hot weather. I grew the variety Cornel, a ball dahlia in a 10 gallon pot. I used a commercial potting mix for the soil and it was on the light side, meaning it had more peat moss and was much more expensive. The plant grew very fast and looked spectacular at it's peak with four perfect blooms all at once. It was all down hill from there. The black pot was way too hot and the flower wanted more water than I could muster. The flowers became very small and the plant looked sick the rest of the season. In other words, dahlias can look great in a pot but keeping them looking great all season is very difficult.

If you do grow dahlias in pots, grow smaller, shorter growing varieties. Nothing more than 3 feet in height.
Water them religiously in hot weather. Give them regular feedings with liquid fertilizers like Miracle Grow. They will probably need a feeding of epsom salts after a couple of months as the liquid fertilizer will have created fertilizer salts in the pot. The plants cannot take up the iron when this happens and the weak solution of epsom salts releases the iron.

Plants in the ground are much easier to take care of. They need less frequent watering and less care in general. Most of our favorite dahlias grow over 4 feet tall and would never grow well in a pot.

I agree with you. I did 10 potted last year and they grew to about one foot and stopped!!! Now I have a garden that has bout 75 tubers in it and everything was fine there. I can't blaime water or soil. They just didn't like the pot. I will try again with a different shape pot. The smaller azeala type. Getting ready for old age with just a patio for 2 plants!!!

Any veterans of this forum may recall my dilemma with a container dahlia from last year so you'll know I have about 10 dahlias in soil but twice that many in pots. I have grown them for 4 years now and while it is true the larger ones do much better in the ground, I have good 4-8" blooms on my container dahlias as a rule.

2010 was also an odd year here in SF. A couple pot growing dahlias came up but never bloomed - a couple gave me only 2-3 blooms. But that was equally true of a couple of the ground dahlias as well. What I have noticed though is most of my good container bloomers are first year dahlias and if I am honest about it, the potted dahlias from years 2,3,4 were not as robust as the first year they were in pots. Not sure if anyone else ever commented on this or noticed it on their dahlias.

But on this forum I learned that my thought processes in 2010 were probably wrong. I had read that excess or 'early' nitrogen was to be avoided so I took that to mean none and I never gave them miracle gro, though I did feed them 0-10-10. What I have since learned is the word excess didn't mean NO nitrogen and apparently that admonition applies to before they start growing anyway. Once they are a foot tall or so, it is apparently OK to use nitro on them so this year I am going BACK to my use of MG on them and hopefully they will all bloom this year.

I am anticipating a troubling crop though this year. We had 80 degree weather in November for a short spell followed by 40 degree weather for much of Dec and Jan. Now it is approaching 70 this weekend for 4-5 days and then we MAY go back to rain, so all this cold-hot-cold-hot-cold may wreak havoc on the tubers. Will have to wait and see.