Germinating the seeds
If you have germinated Begonia seeds before, you may use the same technique that worked for you, because germination is similar.
Getting started -- Plant your seeds when you receive them for best results. Use about 6 to 10 small pots or cups with drainage holes, about 2-4 inches (5-10 cm) tall.
A typical soil mix for germinating them is 3 parts potting soil to 2 parts perlite. An alternate mix is equal parts of coir fiber (or peat moss) and perlite, with some slow-release fertilizer added. Don't add lime to the mix, because the plant prefers slightly acid soil.
The seeds are very small, so work in a well-lit area. Sprinkle several seeds evenly across the surface of each pot. An easy way to pick up the seeds is by breathing on your finger tip to lightly moisten it, then dabbing the seeds with it. Don't sow them too densely, because the germination rate is high.
After sprinkling them on the soil surface, sprinkle 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 sphagnum moss, sprinkle some perlite around the surface.
Add water until the soil is evenly moist, but not soggy. Until the seeds sprout, ensure that the soil surface never dries out. An easy way to maintain high humidity by enclosing the pots in a plastic container or bag - just leave it open a crack to let in fresh air. Once or twice a day, drip a few drops of water on the surface to keep it moist.
The seeds germinate well at about 65-80 degrees F (18-27°C). I don't have experience germinating them outside this temperature range. I recommend placing a minimum/maximum thermometer near the pots, especially if using a heating mat.
Light helps the seeds germinate, so place the containers in a bright spot out of direct sun. A fluorescent or LED bulb kept 4 inches (10 cm) above them provides the right amount of light. Keep the light on at least 12-14 hours per day.
The seeds should start sprouting in 2-4 weeks, but may take longer at cooler temperatures. Continue dripping water on the soil surface after they sprout, since young seedlings have a small root system. Increase the air ventilation slightly after the sprout to prevent rot.
When the seedlings are 1-2 months old, you may carefully dig them up and transplant them, or cut away any slower ones, leaving 1 strong seedling in each pot.
Fertilizing -- For the first 1-2 months, feed weekly with a very dilute (1/8th strength) liquid fertilizer. Hydroponic fertilizer works the best for this, because it is easily absorbed and contains all essential nutrients. After 2 months, you may switch to a slow-release, granular fertilizer and feed every 2 months.
On older plants, it's normal for an older 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 nitrogen fertilizer.
Watering -- Once the seedlings are 4 weeks old, you may stop keeping the soil surface moist at all times. Aim to keep the rest of the soil evenly moist (but not soggy).
Lighting -- The plant likes filtered sun or bright shade + morning sun. Protect it from strong afternoon sun.
Transplanting -- When the seedlings are 2 months old, repot to a larger container about 1 quart (1 liter) in size. Water the soil before repotting, to keep the soil ball from breaking apart, which can damage the roots. Protect from direct sun the first week after repotting.
Climate -- It grows well for me in mild to warm conditions with a drop in temperature at night, similar to intermediate-temperature orchids. I'm unsure how it will do in hot conditions with warm nights. I'm pretty sure it can't survive frost. It prefers relatively humid air - over about 50% humidity is best. If you find that it suffers in lower humidity, consider using an ultrasonic humidifier.
If you have any questions or problems, please email me.
Enjoy your plants!
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