dahlias

I brought dahlia bulbs with me from Portland to San Diego, zone 21, Rancho Bernardo, 2 years ago and of course, they all died. Now that I am a wiser Southern Californian gardener, I know they need better soil and some shade. But my question is that even then, would they be able to grow here? Someone told me I should buy bulbs locally which makes sense, but where would that be? Has anyone in my zone area had success? Thank you.

Helo Nancita,
Dahlias do just fine here. Most areas our soil is not the 'best' but usaully you can improve it so you can grow nice Dahlias. For most soils you should ad lots of organic compost, perhaps about 50% soil and 50% of some sort of good soil amendment. Use about 5# of bone meal to 100 sq. ft. Mix this all up to a depth of about 10" deep (or more if you can). 14" would be better, but some areas you just can't.
We plant the tubers in early spring, about Feb. March is usually fine. I would put a 4' tall redwood stake by each one, when you plant, this way you know exacty where they are and you can support them with the stake as they grow.
Most nurseries have the tubers in late Jan. or for sure Feb. WALTER ANDERSEN NURSERY - POWAY is not far from where you are. They should have what you need.