The "Vegetarian Festival" is actually a religious festival. It is dedicated to the Taoist God - the Ninth Emperor (九皇大帝). The festival is also celebrated in Malaysia, Singapore and Taiwan Chinese communities though in a small scale and the celebrations are quite different.
Dates
As this is a Chinese religious festival, the dates is based on the Chinese calendar. It starts from the 1st day of the ninth month to 9th day. It usually falls in October, though some times it may be as late as November. If you are not familiar with the Chinese calendar, check internet websites for the dates each year.
Stay
If you want to be near the action, stay in or near the old town area in Phuket town. I stayed in Thalang Street which is the heart of the old town. It is also the backpacker's area, with many guest houses and budget accommodation. Alternatively, stay in one of the hotels near the Clock Tower. The Metropole Hotel right next to the clock tower saw one of the most exciting actions on the final night of the festival.
Thalang Street is a good location. It is right in the heart of the old town, which means you can lost yourself in the streets and alleys appreciating the architecture of the historic houses and mansion in the area when you are not watching the procession. It is near the market -- where there is lots of street food every night and a main temple Jui Tui Shrine is found. The other temple Bangniew (or Bangliao) is about 1 km away -- within easy walking distance.
I stayed in 99 Old Town Boutique Guesthouse along Thalang Street. It's a lovely guesthouse in a heritage building. Paid 800 baht a night. There are cheaper options along Thalang Street and Phangnga Road.
Street Processions
The Tourism Authority of Thailand (TAT) published a booklet on the procession and the routes of the procession. I found a copy of it on the internet. I also got a copy from the TAT office which is just by the Queen Sirikit Park along Thalang Street.
The problem with the booklet and most information found on the internet is that they only have information on the day processions. There was no information about the night processions. I asked that TAT office specially about the night procession and none of them knew the information.
I found that the day procession of the Jui Tui temple is the grandest. (It fell on the 7th day this year, I'm not sure if the schedule is fixed yearly). There are the most people who pierced their cheeks as well as other devotee dressed as various deities. It also has the biggest following, for there were more altars set up along the route as compared to other processions.
The procession on the final night is the most festive. The amount of fire crackers exploding was incredible. There were also plenty of fire works. I do not have the information about the night processions, but basically I saw the entourage from 4 temples by stationing myself around the clock tower. the first procession started about 10pm and the last after midnight.
There was also a night procession from Jui Tui temple on the 6th evening. I happened to chance upon it because I was at the temple when it started. I chased after it for a while before I gave up. I believe that was the procession to Saphanhin park where the fire walking was taking place. The procession started at 8pm from the temple and came back after about an hour later.
You can tell where the parade will pass by watching out for the altars people set up along the way. It appears that many processions pass by the clock tower. So that's a good location to wait for the processions.
Residents setting up altars outside their homes along the procession route.
Strategic locations
For atmosphere: the narrow street also made the procession very atmospheric as the entourage squeeze into it. If you managed to get one of the guesthouse rooms with a balcony you can even walked the procession from the balcony!
For fire crackers actions: look for where there are the most fire crackers. I found 2 locations where there was intense fire crackers action on the final night: at Navamindra Memorial Square also Phuket Road. It's just a stone's throw from the Clock Tower opposite the UOB building. The city government had a setup here. The other location is at Metropole hotel, where many visiting devotee stayed at.
Navamindra Memorial Square is a good location for photos as well because it's a two way carriage. You can stay on the opposite site of the street while the entourage pass through in the opposite direction.
The clock tower is also a good location because of the open space. So it is good for photography. Otherwise, station yourself at a traffic junction where the procession frequently has to stop for vehicles to cross. The best is at the junctions where the procession turns.
While it may be atmospheric along Thalang street, the problem is that when it gets crowded, you get blocked all the time. And it is difficult to move around to different locations.
On the final night, I stationed myself at Navamindra Memorial Square. The first entourage came by from the south (from Bangniew shrine) around 10pm. The action was intense. The amount of fire crackers fogged up the street and for a while visibility was only a few meters. And then I went to the clock tower and caught the procession coming back via the road in front of the Metropole Hotel. A few entourage passed by. The last one from Jui Tui passed after mid night.
Visibility reduced due to smoke from the fire crackers.
For photographers
For the day procession, I find that the best locations for photography is at street junctions where the procession has to pause or turn.
The clock tower is another good location as there is plenty of open space around the circle to catch the procession without people blocking.
You can get through close to the procession and frequently the participants are quite willing to pose for photographs.
However, you have to be fearless of the the firecrackers. Getting close to the procession means you risk a stray fire cracker exploding at your feet (which happened to me, but didn't cause any harm).
The debris from the fire crackers can be very bad for your camera. Don't plan on changing lens if you are where the fire cracker actions are most intense -- it's too dusty. I saw some photographers shrink wrapped their cameras. (For my night procession photos, I stuck to Nikon 50mm 1.8 lens).
The photographers who get real close to the action are well attired -- with towels around their face and head.
Photographers fully prepared and geared up.
Etiquette
Devotees wear white during the festival. While visiting tourists are devotees, it is only polite to wear white if you want to join in the celebrations and get close to the processions. This is particularly if you intend to chase the procession and get real close to the action. White tee-shirts and bottoms are sold every where during the festival -- as cheaply as 500 baht each. Sleeveless are apparently fine -- so are shorts. (Just note that while sleeveless T-shirts and shorts are fine in Chinese shrines, they are considered improper in Thai Buddhist Wats. They are unacceptable at Wat Chalong and Big Buddha temple). At the minimum, where a white top to show respect for the local traditions.
You can get real close to the procession (as long as you are not afraid of the fire works), except for the main carriage. When the main carriage pass, you are expected to kneel or squat down (stay far away if you do not want to squat down).
Do NOT bring meat into the shrines during the festival. That would be extremely offensive.
I bought a pair of white pants and a white tee shirt there. While I'm not a devotee, I think it is a matter of being respectful to the local customs, especially since I was getting real close to the processions and temple activities.
For devotees
I found Bangniew to be most accessible to visiting devotees. The temple is big, so there is space to move around. There were frequent announcements in English and Mandarin. They also have a booklet on all their activities in Chinese.
During the Bridge Crossing ceremony, there were announcements in English and Mandarin telling foreign visitors who wish to participate what to do. I saw many tourists joining in. Just note that over the announcements they reported cases of theft of branded shoes. As you are expected to cross the bridge bare-footed, do not wear branded shoes to the ceremony.
It was more difficult to join the Bridge Crossing ceremony at Jui Tui because the temple is smaller and the whole temple was jammed packed during the ceremony. It was difficult to figure out what was going on.
I saw visiting devotees set up altars in front of their hotels. At the guest house where I stayed, some guests set up an altar in front of the guesthouse too. Check with the hotel if you want to do that.
Devotees are expected to observe abstinence during the festival, including observing a vegetarian diet and abstaining from sex. But of course, that is really up to the individual believer. No one will check on you for that.
I am not a devotee nor a believer. But I remembered participating in some celebration devoted to the same Taoist deity in Singapore when I was young. The same deity is worshipped among the Taoist in Singapore -- and there are celebrations during the same time too. But there are no colorful street processions and piercing, nor fire crackers and fire works. However, there is a small procession on the final night and burning of a paper ship by the sea. I read that there is also burning of a paper ship once every three years in the celebrations in Taiwan. But that is not featured in the Phuket celebrations. I did enjoyed the atmosphere and the festivities (and the food of course).