Climate

• It is grown best where the climate is mild without the extreme heat or cold or excessive rainfall.
• Mild climate without extreme of high or low temperature.
• At early stage, plant can tolerate frost.
• temp for seed germination 20-25oC.
• Low temp and short photoperiod are required for vegetative growth, relatively higher temp and long photoperiod for bulb development.
• Lower temperature (1 – 21^oC) and short photoperiod promote vegetative growth while higher temp. (15 – 25^oC) and long photoperiod promotes bulb development.
• Opt temp for veget growth is 13^oC-21^oC and bulb devt opt temp is 15^oC-25⁰
• Adjusting planting time, can be grown from Terai to High Hill
• Onions start bulb formation when the day length is of the proper duration and different varieties of onions require different day lengths to initiate bulbing.
• High temperatures and low humidity are advantageous during bulbing and curing.

Soil

• It can be grown on various types of soil, but it grows best in light soil which may be sandy loam or silty loam.
• Heavy or clay soil should be avoided as they do not permit proper bulb development.
• Deep, friable sandy loam soil with high OM is best
• It is sensitive to acidity or alkalinity . pH 5.8-6.5 .