Germinating the seeds
When to plant -- Plant your seeds when you receive them for best results.
Getting started -- Soak the seeds in a cup of water for 4 to 6 hours (not more than 12 hours).
Soil -- This Cestrum likes soil that's high in organic matter/humus but that also drains well. A good mix is 2 parts potting soil to 1 part perlite or coarse horticultural sand. Most potting soils contain some fertilizer, so if yours does, do not mix in additional fertilizer.
Pot size - You may use small pots about 1.5 to 3 inches (4-8 cm) wide and 2.5 to 4 inches tall (6-10 cm). The pots should have drainage holes.
Fill the pots with the soil mix and water it until it is evenly moist (but not soggy). Place 1 seed on top in each pot, and sprinkle about 1/8 inch (3 mm) of soil over it. Carefully moisten the top soil layer.
Until the seeds sprout, it's important not to let the surface soil dry out. If you place the pots in a plastic container or bag to maintain moisture, leave it open a crack to allow fresh air to enter.
They sprout well at about 65 to 75° F (18-23°C). I have no information about how they will germinate outside that temperature range. I recommend placing a minimum/maximum thermometer near the pots.
Keep them in a bright spot out of direct sun. They should begin sprouting within 6 weeks, but allow up to 15 weeks for any slow ones, especially at cooler temperatures.
Lighting -- Once your seeds sprout, move them to a bright spot, with protection from afternoon sun. You may use a fluorescent light kept a few inches (10 cm) away while your plants are young.
Watering: Once the seedlings are 3 weeks old, you may allow the surface soil to dry out, but aim to keep the rest of the soil evenly moist most of the time. Never let it dry out completely, but also don't keep it perpetually soggy. If your water supply is very high in minerals (= "hard water"), it's best to use bottled water or rainwater.
Feeding -- This species has average fertilizer requirements. Feed about every 2 months with a slow-release (pelleted or organic) fertilizer. If your potting soil contains fertilizer (check the package) your seedlings shouldn't need feeding the first 3 weeks of growth.
It's normal for a few of the older leaves to occasionally turn yellow and drop, but if it seems excessive, the plant may need more fertilizer. It's also possible the soil is too dry down in the root zone.
Climate -- This Cestrum comes mid- to high-elevations, where the climate is mild to cool. I have no information on how much heat it can take, but a related species has been grown successfully in warm places like Florida. Still, consider it experimental in hot climates with warm nights. I don't know its frost tolerance. It grows best above 40 degrees F, although it is probably hardy to 25-30° F (-3°C). Over about 40% humidity is recommended.
Repotting -- Once your seedlings are at least 3 inches tall (7 cm), you may repot them to larger containers about 1 quart (1 liter) in size. Repot gently and avoid letting the soil ball break apart. It's best to water the soil before repotting to keep the soil together. For the first week after repotting, shade from sun and give no fertilizer.
Repot again after 4 to 6 months, or plant in the ground in suitable areas. If you want to keep it in a pot, the final pot size depends on how large you choose to let it grow. You may prune your plant to any size that is convenient. It's best to prune after a flowering flush to avoid removing flower buds.
If you have any questions or problems, please contact me.
Have fun growing them!
Strange Wonderful Things