Its main use in the United States is as large filler (along with peanuts as small filler) in most containers of mixed nuts. Filberts are sometimes grown in orchards for the nuts, but much less often than the common hazel. The purple-leaved cultivar Corylus maxima 'Purpurea' is a popular ornamental shrub in gardens.ts main use in the United States is as large filler (along with peanuts as small filler) in most containers of mixed nuts. Filberts are sometimes grown in orchards for the nuts, but much less often than the common hazel. The purple-leaved cultivar Corylus maxima 'Purpurea' is a popular ornamental shrub in gardens.