More than £10,000 of prizes are available in the Institute of Horticulture-run contest.
The winner will receive the £2,000 Percy Thrower Travel Bursary prize which funds a study trip anywhere in the world, thanks to the Shropshire Horticultural Society which also generously sponsors the Grand Final.
The competition is open to any horticulturist who is below the age of 30 on July 31 including professionals and horticulture students.
Organisers have forecast this to be the biggest competition yet, with more than 2,000 participants.
To take part entrants can attend a heat at a local venue, enter at work with an Institute of Horticulture approved supervisor or apply via Skype. Heats, which test entrants’ range of horticultural knowledge, are taking place now across the UK and Ireland, in the form of 40 multi-choice questions, via a PowerPoint presentation.
The heats will then be followed by eight regional finals, held in March, which culminate in the grand final on May 10 at the John Innes Centre in Norwich.
The 2013 winner, Jez Stamp, said: ‘It was an excellent competition that highlights all the exciting opportunities that horticulture has to offer as a career.
"Plants are my passion. I have thrown myself in 100 per cent and am proud to have won this competition. My travel bursary will give me a chance to continue my studies of woody plants and I will be looking at Western China and Taiwan as possible locations."
TV gardener David Domoney is involved and said the competition was both fun and a good way to network.
"It’s always superbly organized by the Institute of Horticulture, and the contest unites the new stars of the industry on a national basis,
The closing date for entries is February 25.
For more information and a trial run of some previous heat questions click here.
Other sponsors include recruitment company MorePeople, the Horticultural Development Company, The Garden Centre Group and Bulldog Tools.