I forwarded your message to my father, who is a Master Gardener in ABQ.
Here is his reply.

The ones I had two years ago didn't mind full sun at all. They did well in full sun. I think fertilizing is often overdone and I base it on soil measurements and not plant type. Also I grew the Dahlias in both the well amended vegetable garden, raised, b
ed and the un-amended front lawn area. There was no significant difference between the two.



--
Brett Woywood
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* "I seem to be having this * *
* tremendous difficulty with * *
* my lifestyle." * *
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