In Jainism, Chaudas usually refers to Chaturdashi tithi — the 14th lunar day. It is often observed with greater restraint, especially in some traditions and local practices.

Why avoid greens on Chaudas?

The main reason is ahimsa.

Fresh green vegetables, leafy greens, and certain plants are avoided because:

• they contain many subtle living beings
• they are generally considered to have more jiva-baadha than dry grains, fruits, or stored foods
• on spiritually significant days, Jains try to reduce injury to living beings as much as possible

So the idea is not just “greens are bad,” but that their use increases violence toward living organisms, which Jain vows try to minimize.

What is Sandhikaal?

Sandhikaal means the junction period — the transition time between two phases, such as:

• one tithi ending and another beginning
• day and night
• sunrise and sunset

In Jain observance, sandhikaal is often considered spiritually sensitive because:

• the environment is in transition
• many traditions use these times for japa, pratikraman, meditation, or restraint
• some fasts and religious observances are connected with exact tithi boundaries

So when people mention Chaudas and sandhikaal together, they may be referring to the tithi transition and the careful observance around it.

What is Ayushya karma?

Ayushya karma is the karma that determines the span of one’s life.

In Jain karma theory:

• it binds the duration of life in a particular gati or birth
• it is one of the important karmas connected with rebirth
• it is not something that can be changed casually once bound, but its bondage depends on one’s bhav, conduct, passions, and karmic state

This is different from ordinary ritual observance like avoiding greens. Ayushya karma is a deep karmic principle; Chaudas restraint is a practical vow-based observance.

Simple connection between them

• Chaudas: a day of stronger restraint and purification
• Avoid greens: to reduce himsa
• Sandhikaal: an important transitional time for spiritual observance
• Ayushya karma: the karmic basis of lifespan in Jain philosophy

In short, these practices all reflect the Jain ideal of minimum violence, maximum restraint, and spiritual alertness.