Growing the seeds
When to plant -- Plant your seeds when you receive them for best germination
Getting started -- The seeds are small, so work in a well-lit area. Use a well-draining soil mix. A typical mix is 1 part potting soil to 1 part perlite or coarse horticultural sand. An alternate mix is 2 parts coir fiber or peat moss to 3 parts perlite or coarse sand. If you add peat moss, or if your water is "soft" (low in minerals), add a small amount of agricultural lime (dolomite lime, not hydrated or quick lime). Add only ½ teaspoon of lime per gallon of soil (3 cc per 4 liters).
Use small pots or cups that have drainage holes. Fill the pots, without packing down the soil. Place a seed or 2 on top and cover with a thin layer of long-fiber sphagnum moss (not ground peat moss). This helps retain moisture around the seeds while allowing light to reach them, which aids germination. This photo shows how much moss to use. If you don't have the moss, sprinkle a small amount of your potting mix around the seeds. Add water until everything is evenly moist (but not soggy).
Until the seeds sprout, ensure that the surface soil doesn't dry out. A propagation dome or plastic box works well for maintaining moisture. Keep the dome or box open a crack to allow fresh air in. Keep the pots in a bright spot out of direct sun. A fluorescent or LED bulb kept 4 inches (10 cm) away provides the right amount of light.
They sprout well between 68 and 78 degrees F (20-26°C), and a little cooler at night. I have no experience germinating them outside that temperature range. I recommend keeping a minimum/maximum thermometer near the pots, especially if using a heating mat.
The seeds should begin sprouting in 3 to 6 weeks, but allow up to 10 weeks for any slow ones to sprout. Increase the air ventilation slightly after they sprout to avoid rot. Continue keeping the soil surface moist for 3 weeks after they sprout.
Lighting -- Impatiens tuberosa grows well in bright shade, dappled sunlight, or morning sun. It might be able to handle more sunlight, but it will need more frequent watering and feeding. Just avoid strong sunlight until the plants are a few months old.
Transplanting -- When your plants are about 2 inches tall (5 cm), gently transfer them to pots about 3 inches tall (8 cm). Avoid letting the soil ball break apart when repotting. Watering the soil first helps.
Watering -- Try to keep the soil moist, but not soggy, most of the time. Avoid letting it dry out completely. You may use a moisture meter probe to monitor moisture levels down in the root zone.
Climate -- Impatiens tuberosa grows in tropical lowland forests, where temperatures get in the upper 80s (31°C). It can often tolerate warmer conditions than that if nights are cool (below 65°F / 18°C). It's possible that consistently hot days with warm nights might stress it. The tuber can probably survive a light frost, but i recommend keeping the plant above 50 degrees F (10°C).
Fertilizing -- When your seedlings are 1 week old, give a very light dose of liquid fertilizer (about 1/8 strength), and repeat weekly 3 more times. Hydroponic fertilizer is ideal for young seedlings, since it is easily absorbed and complete. After your plants are a month old, you may switch to a general-purpose, granular fertilizer, following the directions on the package.
It's normal for a leaf to occasionally turn yellow and drop, but if it seems excessive, the soil may be too dry down in the root zone, or the plant may need more fertilizer (nitrogen).
Dormancy care - It's normal for the plant to drop it's branches and go dormant for 2-3 months per year. When this happens reduce watering until the soil is just slightly moist. Avoid letting it dry out completely.
Pests to watch for -- aphids, spider mites (tiny "dots" and webbing under the leaves), whitefly, mealy bugs. Be careful when choosing chemical remedies, as some may harm the plant.
If you have any questions, feel free to email me.
Have fun growing them!
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