Answer: If your Brugmansia plants have been in the same pot over the winter, I would transplant them now using a mixture of one part commercial potting soil, one part perlite, and one part screened compost, leaf mold, or well-soaked peat moss. These plants need frequent fertilizing, so you could use a liquid fertilizer once a week. Fish emulsion and seaweed extract provide a variety of nutrients, and they won't cause a build-up of salts in the soil.
By the way, you can quite freely prune your Brugmansias if they get leggy and they will enthusiastically grow new foliage.
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