user22: I have seen the same monk in two different color robes and am wondering why. They were dark red and of course orange. Ihave also seen brown, but that was zen, and if any other colors have relevance i would like to hear about them as well. I practice Theravada if that helps with referencing or relevance issues.

user8262: Since I'm visiting a Buddhist temple here in Chiang Mai I thought that I would answer.  Brown robes can eat only once per day, orange/saffron robes eat twice a day and the maroon (Myanmar) robes can eat whenever they want. That's the word among the monks (they take eating very seriously).

user8091: of all the responses here, i am only surprised that Theravadan women wear white.  my experience is in Nyo Ho E (authentic Dharma clothing) as provided for in Japan especially through the teaching lines of Kodo Sawaki-roshi at Antaiji and brought to North America by trainees through there including Yoshida-roshi and Joshin-sama to Tomoe Katagiri-sama and Blanche Hartman-roshi.  white seems unusual because it is a basic, or primary color (as would be blue, yellow, red, and black).  but there are black robes for training priests in Japan (though the color is supposed to be "off" somehow).  by the same reasoning, i guess i should be surprised that yellow is mentioned a lot, but i am very used to seeing it.  it may be that the "yellow" is "off" somehow.  i think it should basically be modest, and what looks modest has a cultural factor too.  black is modest in Japan.  i think grey is worker / modest in Korea.  maybe in the US, it should be clothes from Walmart ... i don't think that's gonna happen but, that's my sense of the feeling.  very ordinary.

user8238: 
" Bright yellow - China
Black, brown, gray - Japan & Korea "

I want to add this trivia. The original colour of monastic robe in China was black or gray much like its brethen in Japan and Korea from the Dharmaguptaka lineage.
https://en.wikipedia.org/wiki/Dharmaguptaka
However Master Hsing Yun the famous Chinese monk from Fo Guang Shan in Taiwan found that the gambling obsessed Hong Kongers associated the colour black with death and hence was considered unlucky and did not welcome him. So for public appearances he wears the 'golden' yellow robe along with a bright red kasaya, as a form of skillful means. Taking this precedence Chinese monks begin to wear bright yellow robes.
Further more based on my association with the temple and brief experience as a short term novice monk I observed the following:

Within the monastic compound Chinese monks wear bluish gray tunic and
trousers inside for cooking, cleaning, meditation and to sleep.
For ceremonies and public appearances a black robe called the Haiqing is generally worn,
with a dark maroon Kasaya.
During public ceremonies only the ceremony conductor wear the yellow robe
and red Kasaya.
A brown cassock maybe worn for travelling.
You must take off the robes before you go to the bathroom, going in with only the gray inner wear


user11428: Originally, in the first years or so of the sangha, monks would make their own robes from scraps of cloth they found in the trash or in cemeteries, etc.  They would color them by rubbing them with dirt or clay.  After that, any earthy color, found in dying leaves of trees, such as red, yellow, brown, orange or maroon, was acceptable.  Within the Theravada, there's no hard significance between the different colors and shades of colors in this spectrum.  However, you will often find that all of the monks in one temple tend to have the same color and shade.  This is often not 100%, because they accept their robes from dayakas (donors) and they would not reject a robe because it was a different shade.  Similarly, a monk might have brought his robe with him from another temple.
I did see one temple, however, where the head monk had yellow robes, and all of the others had orange robes.  But this was just their practice, and is not from instruction of the Buddha.  

user-1: Oh, In vinaya (code of conduct in monastery) Buddha allowed many types of die to be used for the robe.  Bark from different kinds of tree, or even red color from clay.  so naturally, there would be different shades.   Bark from Jack fruit tree produces brownish color where red clay (like what Andrei said above) produces reddish color.       

user7223: The command was the color Kasava--that means dirty or stained brown. No other color allowed. But the patches and dyes varied, so the Buddha approved the MINOR variations of brown. The idea behind the color is that this is the color of mourning. The entire tricivara is based on ancient Hindu widow's weeds. No one ever answers THIS question correctly. Clerics today should all be wearing a uniform Brown, rather dark brown, end of story.

user43: From my research it looks like the reason that original kasayas (stitched robes, made from leftover pieces of fabric and clothes found on trash piles, taken off corpses etc. - basically the discards of civilization) were ochre or brown-red, is because they were washed with red clay, used as a cleaning agent.
Ochre was the most available color of clay around the area Buddha lived and practiced at.
From this, we can extrapolate and assume that different colors originally derive from different types of clay available in whichever region Buddhism spread to. Later, the colors were standardized by schools and various different dyes were employed beside clay.

user4745: Tibetan lineages wear the maroon color of the cloak out during a Puja, and the yellow out if at giving a teaching.

user143: With the historical significance of the color of the original robes explained by other posters, I'll just add a color chart to identify what regions different colors are mostly associated with today; keeping in mind there are exceptions:
Spice colored robes (shades of curry, cumin, paprika, saffron) - Southeast Asia
Bright yellow - China
Black, brown, gray - Japan & Korea
Maroon - Tibet region and diaspora
White or pink - Theravada women wherever they may be located; although it is noted fully ordained Theravada nuns are rare.
There are some differences in style as well; more detail at source:
http://buddhism.about.com/od/thefirstbuddhists/a/robes.htm

user121: I believe initially the robes were mostly yellow as this was a color of renunciation in the locality at the Buddha's time. As the Dhamma-Vinaya spread the different robe colors occurred due to the local dyes monastics used in their respective localities being different shades and colors.
I do know that in the Theravada tradition at least in Thailand and Sri Lanka there is a differentiation in colors between forest monks and city monks. 
This may be helpful : http://www.buddhanet.net/e-learning/buddhistworld/robe_txt.htm
The robe dye is allowed to be obtained from six kinds of substances: roots and tubers, plants, bark, leaves, flowers and fruits. They should be boiled in water for a long time to get the dun dye. Saffron and ochre (from the jackfruit's heartwood) are the most prevalent colours today. Though there is a tendency amongst forest monks to wear ochre and city monks to wear saffron, but this is not always the rule. 

22: <p>I have seen the same monk in two different color robes and am wondering why. They were dark red and of course orange. Ihave also seen brown, but that was zen, and if any other colors have relevance i would like to hear about them as well. I practice Theravada if that helps with referencing or relevance issues.</p>
 8262: <p>Since I'm visiting a Buddhist temple here in Chiang Mai I thought that I would answer.  Brown robes can eat only once per day, orange/saffron robes eat twice a day and the maroon (Myanmar) robes can eat whenever they want. That's the word among the monks (they take eating very seriously).</p>
 8091: <p>of all the responses here, i am only surprised that Theravadan women wear white.  my experience is in Nyo Ho E (authentic Dharma clothing) as provided for in Japan especially through the teaching lines of Kodo Sawaki-roshi at Antaiji and brought to North America by trainees through there including Yoshida-roshi and Joshin-sama to Tomoe Katagiri-sama and Blanche Hartman-roshi.  white seems unusual because it is a basic, or primary color (as would be blue, yellow, red, and black).  but there are black robes for training priests in Japan (though the color is supposed to be "off" somehow).  by the same reasoning, i guess i should be surprised that yellow is mentioned a lot, but i am very used to seeing it.  it may be that the "yellow" is "off" somehow.  i think it should basically be modest, and what looks modest has a cultural factor too.  black is modest in Japan.  i think grey is worker / modest in Korea.  maybe in the US, it should be clothes from Walmart ... i don't think that's gonna happen but, that's my sense of the feeling.  very ordinary.</p>
 8238: <blockquote>
<p>&quot; Bright yellow - China</p>
<p>Black, brown, gray - Japan &amp; Korea &quot;</p>
</blockquote>
<p>I want to add this trivia. The original colour of monastic robe in China was black or gray much like its brethen in Japan and Korea from the Dharmaguptaka lineage.</p>
<p><a href="https://en.wikipedia.org/wiki/Dharmaguptaka" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Dharmaguptaka</a></p>
<p>However Master Hsing Yun the famous Chinese monk from Fo Guang Shan in Taiwan found that the gambling obsessed Hong Kongers associated the colour black with death and hence was considered unlucky and did not welcome him. So for public appearances he wears the 'golden' yellow robe along with a bright red kasaya, as a form of skillful means. Taking this precedence Chinese monks begin to wear bright yellow robes.</p>
<p>Further more based on my association with the temple and brief experience as a short term novice monk I observed the following:</p>
<ul>
<li>Within the monastic compound Chinese monks wear bluish gray tunic and
trousers inside for cooking, cleaning, meditation and to sleep.</li>
<li>For ceremonies and public appearances a black robe called the Haiqing is generally worn,
with a dark maroon Kasaya.</li>
<li>During public ceremonies only the ceremony conductor wear the yellow robe
and red Kasaya.</li>
<li>A brown cassock maybe worn for travelling.</li>
<li>You must take off the robes before you go to the bathroom, going in with only the gray inner wear</li>
</ul>
 11428: <p>Originally, in the first years or so of the <em>sangha</em>, monks would make their own robes from scraps of cloth they found in the trash or in cemeteries, etc.  They would color them by rubbing them with dirt or clay.  After that, any earthy color, found in dying leaves of trees, such as red, yellow, brown, orange or maroon, was acceptable.  Within the Theravada, there's no hard significance between the different colors and shades of colors in this spectrum.  However, you will often find that all of the monks in one temple tend to have the same color and shade.  This is often not 100%, because they accept their robes from <em>dayakas</em> (donors) and they would not reject a robe because it was a different shade.  Similarly, a monk might have brought his robe with him from another temple.</p>

<p>I did see one temple, however, where the head monk had yellow robes, and all of the others had orange robes.  But this was just their practice, and is not from instruction of the Buddha.  </p>
 -1: <p>Oh, In vinaya (code of conduct in monastery) Buddha allowed many types of die to be used for the robe.  Bark from different kinds of tree, or even red color from clay.  so naturally, there would be different shades.   Bark from Jack fruit tree produces brownish color where red clay (like what Andrei said above) produces reddish color.       </p>
 7223: <p>The command was the color <em>Kasava</em>--that means dirty or stained brown. No other color allowed. But the patches and dyes varied, so the Buddha approved the MINOR variations of brown. The idea behind the color is that this is the color of mourning. The entire tricivara is based on ancient Hindu widow's weeds. No one ever answers THIS question correctly. Clerics today should all be wearing a uniform Brown, rather dark brown, end of story.</p>
 43: <p>From my research it looks like the reason that original <em>kasayas</em> (stitched robes, made from leftover pieces of fabric and clothes found on trash piles, taken off corpses etc. - basically the discards of civilization) were ochre or brown-red, is because they were washed with red clay, used as a cleaning agent.</p>

<p>Ochre was the most available color of clay around the area Buddha lived and practiced at.</p>

<p>From this, we can extrapolate and assume that different colors originally derive from different types of clay available in whichever region Buddhism spread to. Later, the colors were standardized by schools and various different dyes were employed beside clay.</p>
 4745: <p>Tibetan lineages wear the maroon color of the cloak out during a Puja, and the yellow out if at giving a teaching.</p>
 143: <p>With the historical significance of the color of the original robes explained by other posters, I'll just add a color chart to identify what regions different colors are mostly associated with today; keeping in mind there are exceptions:</p>

<p>Spice colored robes (shades of curry, cumin, paprika, saffron) - Southeast Asia</p>

<p>Bright yellow - China</p>

<p>Black, brown, gray - Japan &amp; Korea</p>

<p>Maroon - Tibet region and diaspora</p>

<p>White or pink - Theravada women wherever they may be located; although it is noted fully ordained Theravada nuns are rare.</p>

<p>There are some differences in style as well; more detail at source:</p>

<p><a href="http://buddhism.about.com/od/thefirstbuddhists/a/robes.htm">http://buddhism.about.com/od/thefirstbuddhists/a/robes.htm</a></p>
 121: <p>I believe initially the robes were mostly yellow as this was a color of renunciation in the locality at the Buddha's time. As the Dhamma-Vinaya spread the different robe colors occurred due to the local dyes monastics used in their respective localities being different shades and colors.</p>

<p>I do know that in the Theravada tradition at least in Thailand and Sri Lanka there is a differentiation in colors between forest monks and city monks. </p>

<p>This may be helpful : <a href="http://www.buddhanet.net/e-learning/buddhistworld/robe_txt.htm">http://www.buddhanet.net/e-learning/buddhistworld/robe_txt.htm</a></p>

<p><strong>The robe dye is allowed to be obtained from six kinds of substances: roots and tubers, plants, bark, leaves, flowers and fruits. They should be boiled in water for a long time to get the dun dye. Saffron and ochre (from the jackfruit's heartwood) are the most prevalent colours today. Though there is a tendency amongst forest monks to wear ochre and city monks to wear saffron, but this is not always the rule.</strong> </p>
