After some internet search, many website suggest chilling to enforce Hippeastrum to bloom.
At first, I am not too sure on the success rate of forcing, I tried twice and success.
Now i am trying again, with 3 mixed bulbs. The bulb goes into the fridge on 6 Jan 2016.
Some important condition to increase the probability of blooming:
1. Leaves Count
The plant to be chilled ideally has minimum 6 healthy leaves. More leaves means bigger bulb and most probably will give 2 flower stalks.
2.Chilling Period
The minimum chilling period is 4 weeks, ideally 6 weeks. Some plants has entered dormant period while in the garden, so they need only 4 weeks in the fridge. For active growing plant, minimum 6 weeks is required in the fridge. Plus or minus is 2 weeks more in the fridge, the longer they stay in the fridge means they sleep longer, therefore increase the probability of success of blooming.
3. Bulb Size
Bigger bulb means more mature bulb. But how big is it ? The size of the bulb depends on the type of Hippeastrum. Simphony type with large or super large flower requires minimum bulb 25cm circumference.
Sonatini type (the smallest) requires minimum bulb 15 cm circumference. The Sonata type requires in between the size of Symphone and Sonatini. Based on my experience, bulb size over 34 cm in circumference hardly fail to bloom and shall give minimum 2 flower stalks.
4. The Temperature
From internet browsing, optimum temperature for chilling is 10 degree celcius. The compartment in the fridge to store vegetables has ideal temperature for chilling. Remember do not store the bulb where the temperature could go lower than 5 degree celcius, the bulb will be frozen and perish.
5. Etilene Gas
Some grower advise to avoid etilene gas during chilling, as this gas will destroy the bud in its initial stage.
Well known fruit that produce this gas is Apple. Make sure when the chilling is in process, do not store apple in the fridge. The level of gas affected the bulb. I think 2 to 3 apples or less than one kilogram does not harm the bulb as long as the fridge door is opened daily to ensure exchanging of air.
6. Dry Bulb
Remember to dry the bulb before it goes into the fridge. Humid bulb will trigger bacteria/fungi to grow and the bulb will be rotten. The best drying method is air dry. Just dig out the bulb, wash the bulb completely and let the bulb sitting in the porch for 3 to 5 days. Make sure it does not get direct sunlight and the area have good air flow. If the bulb need to be transported very soon, then 'hair dryer' could be used for a few second.
7. Root
The decision to leave the root intact depend on the aesthetic look and how has the bloom is expected.
Hippeastrum requires 2 to 3 weeks to grow roots once come out from the fridge. If the root is left intact, they can absorb nutrient from soil faster and speed up the bloom. If the bulb will be flowered on water, then some healthy root must be left. If the bulb to be sold in nice packaging, then the root to be trimmed completely.
Above 7 conditions if fully met, will guarantee the bulb will bloom once chilling process is done.
