Container size -- A 1 or 2 gallon size pot is perfect to start with. Plan on transferring to larger container (or into the ground) when the roots poke out of the bottom of the container - probably in a few months.
For soil, use a well draining mix. Personally i use a mix of 1 part coir fiber to 1 part perlite (use fine- or medium-grade perlite, not coarse-grade). An alternate mix is 2 parts potting soil to 1 part perlite.
Transplant tips -- Avoid disturbing the root-ball whenever you transplant. Before removing your plant from its pot, give it a watering if the soil looks dry, so the soil doesn't break apart, which can damage the roots.
Light -- Your plant was grown in filtered light, not direct sun, so it should be acclimated to direct sun slowly. This will give your plant time to grow a larger root system, so it can handle more light. So start your plant with either tree-filtered sunlight, or morning sun, so that it gets about 25% sun each day. Every few days, move the pot into slightly more sun. If the leaves should wilt, simply give it a little more more shade for a few days. Eventually work up to about 75% sun. They appreciate some mid-day shade in warm areas.
Watering -- Iochromas do best with regular waterings. Don't let it dry out completely, but don't keep it constantly soggy either. You may use a moisture meter to monitor the moisture levels down in the root zone.
Fertilizing -- Feed your plant about every 2 months during periods of active growth using a granular fertilizer that contains micronutrients. Follow the dosage on the package.
Placement in the garden -- Full sun may be too much for this Iochroma, except in cool areas like near the Pacific coast. It might need some afternoon shade in strong sun.
Protect the plant from frost. It can tolerate light frosts, but it may lose branches. Provide overhead protection in mild-winter areas. In cooler areas, bring indoors before frost is expected.
Pruning & shaping -- Pruning isn't necessary, although you can prune it if it gets leggy. Prune in the fall to avoid removing budding sites. Avoid pruning more than 15-20% of the plant in a 10 day period.
Bugs to watch for -- Whitefly, spider mites (tiny "dots" under the leaves), mealybugs, Japanese beetles, aphids (green ones are hard to see), snails/slugs.
If you have any questions or problems with your plant, feel free to email me.
Enjoy your plant!
Strange Wonderful Things