I'm about to purchase a few Brugmansia sanguinea and I'd like to plant them permanently in the ground. The location is under the overhang of the roof in a mostly gravel soil. I'm hoping to overwinter them so should I be amending the soil with organics or should I be growing them lean with the gravel? What's the best winter mulch to protect the roots and bottom of the stems?

I've only just seen this and I can only relate my experiences of growing it here in the UK. Anyway, here goes..........

Firstly, B.sanguinea is a winter blooming species although in reality here that means autumn plus autumn and spring if kept frost free. Frost kills all green growth.
Mine has seen -12°c in the ground and survived, -7°c in a pot. However, such harsh treatment does result in slow initial growth as it comes back from the rootstock. Now that I have my new greenhouse ready it will be kept frost free from now on.
The best flower colours come during cool periods. It will intermittently bloom in the heat of summer but colours are poor and I tend to cut the buds off early.
All members of the Brug family are greedy feeders so definitely improve the soil and add feed regularly whilst in growth.

I hope that this helps.

Brugmansia sanguinea by longk48, on Flickr

Thanks for your comments. I found mixed comments about hardiness so your experience speaks volumes. My climate is almost identical to yours so it should work out. Unfortunately, my brugs got hit by a heavy infestation of spider mites so it looks like they'll be spending winter indoors for the first year recovering. I was also hesitatant putting the B. sanguinea on the south side of the house in full sun or should I put it in a location that doesn't get blasted from summer sun?

islander said:Thanks for your comments. I found mixed comments about hardiness so your experience speaks volumes. My climate is almost identical to yours so it should work out. Unfortunately, my brugs got hit by a heavy infestation of spider mites so it looks like they'll be spending winter indoors for the first year recovering. I was also hesitatant putting the B. sanguinea on the south side of the house in full sun or should I put it in a location that doesn't get blasted from summer sun?

I would hesitate to plant out first year plants here. After winters here it comes back from below ground so you want to build up a large and strong "basal trunk". A big problem in that respect is that new growth will be hollow as it dies back allow winter wet in and causing rot from the inside out. So this basal area needs maturity before subjecting it to winter stress. If you can cover them to protect against water rather than cold that would be a plan.
The bloom season is harder to get around so basically if it were me I would be expecting autumn blooms only.

I hope this helps.

The location where I plan to plant the plants is under an overhang of the roof for the very reasons you mention. The soil is mostly rock ontop of drain tile so the drainage is exceptional. I'll amend it when planting. The plants are all about a metre or more in height so the plants are definitely a few years old. I can't believe I didn't notice the spider mite damage earlier. Thanks for your comments as the majority of info online is confusing, particularly about B. sanguinea. Normally we have lows around -5 at most but the past winter was exceptional with -10C. As you say, it's the wet not the temps as much that make the difference in hardiness.

A metre is less than what I would expect in a season to be honest. Out of interest how large is the base of the trunk (have a gentle poke around the top of the soil)?

Apologies are due as I did mean to edit my previous post to add the following;
I do find that they wilt in strong sun. They soon recover though.

As you can see by the pic, the plants were in a constant state of decline since I got them a few months ago. I was unaware it was spider mites until I notice webbing. The tallest is 5' but the bases are fairly large/mature. I still think I should keep them indoors this winter to let them recover and continue spraying for spider mites. Surprisingly there is a banana only 2 metres away that had no mites.

Yup, good sized plants. They're spider mite magnets so my preference would be to overwinter them as cool as possible but frost free.