Twenty Dutch growers were selected to provide (parts of) horticultural crops. The parts could be, for example, bulbs, stems, or flowers. The extract library received in total 2271 parts of plants, which belong to 1299 horticultural species. The species belong to 927 genera and 196 families. The crops were grown pesticide-free according to an agreed protocol. The protocol enables the growth of additional plant material under similar conditions, if needed. The extract library has the exclusive right to use the plant material. It was partially used for extraction (see extracts). The remaining is stored as back-up at minus 80˚C.