The 15m border at the Oxfordshire garden is half the length of the existing border, created in the 1930s by Beatrix Havergal and considered one of the finest purely herbaceous borders in the country.
"Havergal's border is fairly plain in winter and beautiful from May to October and it represents the old Waterperry," explained events manager Susie Hunt.
"It is high maintenance, needing watering, weeding and staking. The new border has a more aspirational feel and includes drought-tolerant stock densely planted to cut down weeding."
She added: "It taps into current buzz themes such as prairie planting and is the antithesis to the existing border with plants having to meet strict criteria, such as long-flowering seasons and low upkeep."
Horticulture manager Robin Jacobs included eucrium hircanicum 'Paradise Delight', Sedum 'Jose Aubergine', Persicaria amplex 'Rosea', Echinacea p. 'White Swan', Miscanthus nepalensis and Carex muskingumensis.