Winners will receive prizes valued at more than £10,000. Heats will take place across GB and Ireland from early January until late February before regional finals and the grand final at the John Innes Centre, Norwich, on 10 May.
Organising committee vice chairman Graham Porter said he is expecting between 2,500 and 3,000 entries, up from last year's record of 2,000 and way better than the 500 entries 15 years ago.
"Social media is having an effect," said Porter. "We seem to be attracting more entries from industry, not necessarily students. We have an extra sponsor this year, the Garden Centre Group, so there's a larger pot for prizes, which should be an added draw. The more entries we have, the more sponsorship we are likely to get."
Sponsors to date include Shropshire Horticultural Society, MorePeople, the Garden Centre Group, the Horticultural Development Company and Bulldog Tools.
The competition is open to any horticulturist under the age of 30 on 31 July 2014. See www.horticulture.org.uk/page.php?pageid=562.