Your tuber should be planted when received
Pot size -- The tuber will grow and multiply very quickly and will eventually need a pot at least 14 inches (35 cm) wide, with a height of at least 7 inches (18 cm). But I recommend starting your tuber in a smaller pot about 5-7 inches (12-18 cm) wide, and transplanting it 3 or 4 months later to a bigger pot.
Soil -- Like most Impatiens, this one likes moist, fertile, well-draining soil. A typical mix is 2 parts potting soil to 1 part perlite or coarse sand. An alternate mix is equal parts of coir fiber and perlite, with some slow-release fertilizer added.
Planting -- The side which has more root nubs should be planted downward. Plant your tuber with the top of it about 1 inch (3 cm) under the soil. If you prefer to watch the tuber grow and multiply, plant it with the top of the tuber right at the soil surface. Water the soil just enough so it is evenly moist, and keep it this moist until a shoot appears. It should send up a shoot within 4 to 6 weeks if grown indoors.
Climate -- The preferred temperature range is between 40 and 80 or 85 degrees F (5-29°C). It might be able to tolerate warmer conditions if nights are cool. If your plant looks unhappy in hot weather, you may need to bring it into an air conditioned, humidified room.
Watering -- Once your tuber sprouts, keep the soil evenly moist. Never let the soil dry out completely, but also don't keep it soggy either.
Lighting -- This Impatiens does best in bright, filtered light, or morning sun + bright shade. Strong, hot sun might burn it. In warmer conditions, keep the plant well shaded.
Fertilizing -- Your Impatiens likes average amounts of fertilizer. Feed about every 2 months with a general-purpose fertilizer.
Humidity - If you are growing it indoors, and your room humidity is under 40%, consider using an ultrasonic room humidifier, which you can buy inexpensively at places like Home Depot and thrift shops.
Pruning -- Pruning isn't necessary. This Impatiens usually makes a single main stem with few side branches. Pruning the top will encourage the side branches to grow fuller.
Dormancy care -- The plant usually goes dormant in winter, if temperatures are cool enough. If the stem starts to die back or wilt, that's a sign it's preparing for dormancy. This can happen indoors too after a year or two of growth.
While the tuber is dormant, ensure that the soil does not dry out completely. If you pull the bulbs up to separate them, place them back into lightly-moist soil, so they don't dry out. The bulbs are fairly rot-proof, but avoid letting the soil get too wet while dormant.
Indoors, the plants may grow continuously for a year or more, until they get tired of flowering and go dormant. Once dormant, move them to a cool spot for 3 months. After 3 months, move them back to a warmer spot to encourage them to come out of dormancy.
Outdoors, the dormant tubers are hardy down the low-20s (-5°C) if planted deep and kept dry and well mulched - but it's best to bring the tubers indoors for the winter.
Pests to watch for -- Look for other pests that may affect your other plants.
If you have any questions, feel free to email me.
Good luck with it!
Strange Wonderful Things