The collections at the Argotti Botanic Gardens & Resource Centre comprise representations of major plant families that are adapted to a Mediterranean-type bi-seasonal climate, prominently a mild, wet rainy season alternating with a hot, dry season.

Five regions share these characteristics, namely Central Chile in South America, California in North America, Cape region of South Africa and Southern Western Australia, apart from the lands of the Mediterranean basin itself. The plant collection also includes representatives from the Canary Islands and Madagascar as well as succulents and cacti from other regions of America and Africa.

The Argotti Botanic Gardens & Resource Centre host a number of mature botanical specimens planted over the years that include the Argania spinosa (Argan Tree), Ficus macrophylla (Australian banyan), Jaracanda mimosifolia (Jacaranda), Lagunaria patersoni (Primrose tree), Pheonix canariensis (Canary Island date palm), Quercus coccifera (Kermes oak), Tetraclinis articulata (Sandrac gum tree), Tipuana tipu (Rosewood, Pride of Bolivia), Trachycarpus furtunei (Chinese windmill palm). There are also several large Cactus and Euphorbia specimens.

The part of the garden dedicated to the Mediterranean basin contains endemic plants such as Atriplex lanfrancoi (Maltese cliff orache), Cheirolophus crassifolius (Maltese rock centaury), Darniella melitensis (Maltese salt tree), Helichrysum melitense (Maltese everlasting) and Matthiola incana subsp. melitensis (Maltese stock). The botanical collections are now organised by families, light and water requirement regimes.