Container size -- A 1 to 3 gallon size pot is perfect for the first 1-2 months.
Watering -- Try to keep the soil evenly moist at all times (but not soggy). Don't allow it to dry out. If you're unsure if the soil down in the root zone has the right moisture, you may use a moisture meter.
Fertilizing -- Feed about every 2-3 months with a general-purpose fertilizer that contains micronutrients (I use this one).
Climate -- Full sun is usually too much for Red Brugmansia, except in cool, coastal areas like California. It flowers best in cooler temperatures, so give it afternoon shade in warm climates.
Mature plants can tolerate light, brief frosts, but try to provide overhead protection. If the freezes aren't hard, new growth will emerge from under the mulch in the spring. I recommend protecting young plants from frost the first 2 years.
Pruning & shaping -- Pruning isn't necessary, but you may prune your plant to any shape you wish. Avoid removing too many leaves at one time.
Bugs to watch for -- Whitefly, spider mites (tiny "dots" under the leaves), Japanese beetles, aphids (green ones are hard to see), snails/slugs.
If you have any questions or problems, feel free to email me.
Enjoy your plant!
Strange Wonderful Things