Growing dahlias in pots can be very frustrating as they require so much attention. Plants in the ground do not need to be watered every day and sometimes twice per day as do dahlias in pots. Smaller varieties do ok in pots and the pot needs to be at least 5 gallons. Tree pots of 30 or more gallon size work best. A pot buried part way into the ground is an excellent solution. The pot can be much smaller and even gallon sized pots work well. One commercial cut flower grower in Northern California grows all his very many dahlias in partially buried pots.

Califox

I live in San Francisco and have about 15 dahlias in different sized pots. So they can grow well in pots but Ted is correct - it takes more work AND by far the most important thing is size of the pot and soil.

Firstly, only one tuber per pot unless you have a huge 14 inch pot and want to try growing a low dahlias (3') IN FRONT of a larger dahlia (4 1/2 -5 '), which I have done with success. Assuming you only have 1 to a pot, my advice is make the pot as large as possible (at least 8" and preferably 10-12") and use a combo of potting soil and regular garden soil.

The next main thing is DO NOT Water until they sprout and show about 4-6 inches of sprout. Expect first year dahlias to maybe show reluctance to growing. I've found 2nd and 3rd year dahlias do much better than they did in their first year.

Some people advocate moving the pot around according to heat or cold and amount of sun. I am not a fan of that myself - I have some growing in SHADE for the most part and they 'took' just fine. I also found they adapt to their conditions and moving them around never gives them the opportunity to establish a sun pattern they can grow into. but this is your choice - again, many people say move them from one area to another so I assume they also get good results.

Good luck.

Thanks so much for the tips; both responses are incredibly helpful. I originally was going to grow in pots but it seems I may try in the ground instead now. Any advice on preparing the soil? I know good drainage is super important with bulbs and the like. Thanks again!

How acid is your soil? Unless your soil is over into the basic range, dahlias like a bit of lime added as well as good compost. I like to add organic tomato or veiatable fertilizer when I plant them. Put in a post or stick for them to be tied to, when you plant and while you know where the tuber is so you don't spear it later.

I am zone 14 in Sacramento and have grown them for years. So our climate is similar. I would dissuade you from growing in pots because it's too hot here and the plants prefer to be in the ground where it is cooler. I do start my tubers in pots in the spring before I transplant to the garden soil. Another advantage of this strategy is that the tender sprouts are protected from slugs & snails when they are most vulnerable. I transplant when they are about 8-12" tall and they are less tasty to slugs & snails.

I have grown some in pots but generally I believe they are only marginal in pots here in this climate.

If you want to get some 4 to 6 inch cow pots, you could pot them up now and plant pot an all when it gets warmer n the ground.