Seven competitors from around the region are taking part - the absolute maximum is eight.
"Nationally, all the regional competitions are full," Mr McNeil said.
Hawke's Bay is the first of the five regional competitions to be held.
The others - in Auckland, Marlborough, Wairarapa and Otago - take place over the next month.
Competitors must be under 30 years old and currently working in the New Zealand wine industry.
This year's Hawke's Bay contestants are Imogen Bell-Butler, Anton Luiten, Chris Borain, Jascha Oldham-Selak, Jono Hunt, Ash Hellam and Ben Richards.
Anton Luiten and Jascha Oldham-Selak placed second and third in last year's regional competition.
The national final is in Marlborough on August 29, and the overall winner goes on to compete at the national Young Horticulturist of the Year competition.
Six out of the past 12 young horticulturist contests have been won by contestants from viticulture, said national co-ordinator Nicky Grandorge.
One of those was the 2015 winner of the Hawke's Bay competition, Caleb Dennis.
Prizes for winning New Zealand Young Viticulturist of the Year include $2000 cash, a $5000 travel grant and the use of a Hyundai Santa Fe for a year.
Rewards for regional winners include $1000 cash and travel expenses to the national final.
But prizes are not what competitors gain the most benefit from, Ms Grandorge said.
"The main thing is it really just opens the door for their careers."
The competition is due to start at 9am on Thursday at Te Awa Estate Winery and finishes at 3pm.
A pruning competition, Silver Secateurs, will be held alongside the Young Viticulturists' competition.
Spectators are welcome throughout the day, with a complimentary barbecue provided.