At the end of February, Gardener's World screen tested eight candidates from 400 applicants.
Chelsea Physic Garden curator Nick Bailey and Love Your Garden presenter Frances Tophill are two who have been successful. More will be seen of garden designer Adam Frost too.
A BBC spokesperson said they did not know who else would appear, adding: "There will not be a change in the line-up of GW presenters. Monty, Carol, Joe & Rachel will appear across the series as always. However there’ll be several new faces over the course of this series on the show. We will run biogs of the new faces on our Facebook site prior to their appearance on the show."
In the latest programme Glenn Sheldrake from Burford Garden Company told Rachel de Thame that viburnums, herbaceous perennials and 'the naturalistic look' was fashionable.
He recommended Viburnum Mariesii Great Star, philadelphus, Highgrove climbing rose and magnolia 'Susan'. De Thame recommended lilac Souvenir de Louis Spaeth and Cryptomeria.
Presenter Joe Swift visited Roundstone Nurseries, which grows 65 million bedding plants a year for B&Q, as well as 5.5 million packs and 4.5 million pots.
Newey said the consumer decided what they want to buy. He split gardeners into experienced and novice, who are "not so set in their ways".
He said plants had to be "trendy" which alarmed Swift, who questioned this. Newey said it was "buying a blend of products that looks interesting, such as bedding, herbaceous and tropical.
Swift said he did not like "lairy" colours such as pink polyanthus and said beddingw as "fun".
Monty Don warned about planting too early, "even if plants are for sale at garden centres" adding that some will "suffer terribly".