Yes you can. It gets them off to good start for next year when the bloom will be at its best. Of course I am in California, so don't know how they deal with your winter. Al

August and September can be too late. I start them in May or June . I have grown Delphiniums for decades. My observations are:

1)Never ever use anything with Pacific and Magic Fountains series in the name. These plants have never been selected for other things than flowers. They last 2 or 3 years at the best.
2) Instead you have to sow Delphinium elatum hybrids for example Foerster's hybrids. They have a lifespan of at least 10 years. I have some going in their teens.
3)If you can get your hands on following cultivars, they are the winners. You don't even need staking in normal situations: Augenweide, Waldenburg, Sommerwind, Lanzentraeger,Ouverture. Ouverture and Augenweide are also resistant to fungi.

Thanks for the advice... I really love the Royal Aspiration blue delphiniums wieslaw... is it possible to plant those?

I have to both agree and disagree with Wieslaw.
I also think now would be too late to start delphinium from seed.
But Pacific Giant are D. elatum, and their longevity depends on your conditions. Mine have been in their place for at least 20 years. Out of 7 plants, I've only replaced 2 in that time.

Here is a link that might be useful: {{gwi:250291}}

Without a doubt this is my favorite... I want this in my garden big time!

Here is a link that might be useful: {{gwi:252999}}

Mytime:
Long ago I read the history of the Pacific Giants. As far as I recall they are not pure elatum, as some short lived californian species somehow got involved in the beggining, and it still shows. And even if I remember wrongly,I know they were NOT SELECTED either for longevity or resistance to diseases(mildew).It is not only 'my problem' . You can read about it on each second delphinium site, or ask any serious delphinium developer. You were just lucky, that's all. So my warning is still valid: no Pacific Giants or ANY of their relatives. Pure elatum hybrids grow well for me in the same situations.

The loudly advertised hybrids from New Zealand(Royal Aspirations among them) are advertised as having strong stems, not needing staking. It was not true for me.

Wieslaw, do you have any suggestions for sources of the ones you name above (Augenweide, Waldenburg, Sommerwind, Lanzentraeger,Ouverture...)? Are these among the Foerster Hybrids?

I grew some Centurion hybrids and liked them very much, even though they were fussy about germinating and seemed weak and sickly for several weeks as seedlings. But once they got established in the garden they were beautiful. The double white was among the loveliest whites I've seen in a delph.

I'd be happy to hear others' opinions on hybrids they recommend.

Here in Minnesota I start them in late December or early January and can usually get some flowers the first season. They don't really take off until the second.

Gary

Garystpaul,
I doubt you can find them in the US. These are German varietes, so you can find them in majority of nurseries in Germany, Austria, Switzerland, Holland, Belgium, and I have also seen some of them listed in England sometimes. Can you buy from this countries?
Austria:
http://www.sarastro-stauden.com/ you just choose 'Sortiment' and then letter D on the right

Germany:

http://www.stauden-stade.de/ You just write 'delphinium' in Suchbegriff

http://www.gaissmayer.de/ you click on eshop, then Botanischer index, and you choose D.

You can also use The Plantfinder from England to find the plants in the UK.

Here is a link that might be useful: Karl Foerster's original plants

Adam, I tried many years to grow these in 5b and they so rarely lived through winter. After years of reading the forums, the general consensus seems to be that excellent winter drainage is the critical factor. Heavy clay is usually a death sentence for them. I have no scientific terms or cultivar names but the only ones I had survive once in a while were the ones with very fat, fuzzy-ish leaves. They also like to croak in the summer if it gets really dry, one of the first plants to do so. Haven't bothered trying them in the south.

I also know the only to succeed is to keep trying until it goes right. Good luck!

Delphiniums are among the hardest plants ever. I had them in zone 4 and never lost one to frost. You are probably talking about Pacific Giants. They were bred in California. No wonder they can be delicate.

Up here in the Northeast I've had mixed results. I usually have to buy new ones every other year. They are lovely and I must have some in my garden. I would agree starting seed now is too late. Do it in the spring. I deadhead the flowers and they will rebloom for you throughout summer.

Here in the mid-atlantic zone 6, I've had good luck with delphinium belladonna. This one is Cliveden Beauty, and it's survived about 7 winters so far.

{{gwi:253002}}