Several varieties of plants she cultivated were recognized with awards from the Royal Horticultural Society in London and she was elevated to Baroness by Albert II of Belgium for her contributions to dendrology.

Graduating in 1951, with a degree in agronomy, she worked for a year at the city nursery on the outskirts of Zagreb and then in 1953 was granted a rare permit from Yugoslavia to study abroad.

[2] The brothers also founded the International Dendrology Society (IDS) at Kalmthout in 1952, to promote preservation and conservation of rare or endangered woody plants.

Robert named the variety, Hamamelis × intermedia Jelena and entered it that year at an exhibition held in London by the Royal Horticultural Society.

[7] Within ten years, the arboretum had reached capacity and the couple bought another, much larger estate, Hemelrijk in Essen, Belgium,[2] containing 250 acres (101.171 hectares).

[3] One of the seedlings named after their daughter Diane, received the Award of Garden Merit in 1993 from the Royal Horticultural Society for its intense red color.

[2] During an economic decline fueled by the oil crisis, Robert's diamond business suffered in the 1980s, and the couple turned the arboretum over to the Province of Antwerp.

She was the author of a cookbook, Okus po cvetju: kulinarično popotovanje (Ljubljana: DZS, 1994 [A taste for flowers: a culinary journey])[1] and Life Begins in Autumn (1998).