It was a last-ditch effort for the young gardener, as 2015 is the last year in which she was eligible to enter the competition. She came nail-bitingly close in 2014 only to claim the runner-up spot in the grand final.
"Having finished second in the competition last year, my overwhelming emotion when the final scores were announced was relief," Evans said.
"I would now really like to support the running of the competition, and to encourage others to take part, as it is vitally important to celebrate the quality and knowledge of young horticulturists."
Evans represented the southwest branch of the institute at the grand final held in Somerset on 9 May.
She won the coveted £2,500 Percy Thrower Travel Bursary, which enables the competition winner to undertake a trip anywhere in the world to study a subject related to their chosen field of horticulture. It is provided by the Shropshire Horticultural Society.
The institute's president Andrew Gill said: "Jessica Evans was the clear winner on the day and I feel that her calm maturity, combined with her passion for plants, will ensure she excels as an ambassador for the Chartered Institute of Horticulture.
"The Young Horticulturist of the Year competition is more important than ever to the Institute and horticulture in general, as we encourage and develop the horticultural professionals of tomorrow, tapping into the current popularity of growing plants; there is no more satisfying job."
The competition is now in its 26th year. More than 1,800 young horticulturists from across the UK and Ireland took part this year.
1st place - Jessica Evans, Head Gardener, Tintinhull Gardens, National Trust - representing the South West Branch
2nd place - Alexander Hankey, Student at the Royal Botanic Gardens Kew - representing the South East Branch
3rd place - Josh Egan-Wyer MCIHort, Nursery Manager, Pershore College - representing the West Midlands and South Wales Branch