A Hybrid is essentially a cross-breed between two or more plant varieties of the same species – in this case, two eucalyptus varieties. The varieties selected by Researchers, to make the most suitable hybrids for Uganda were: E. Grandis, E. Camaldulensis and E. Urophylla.

E. Grandis is always the mother tree in the hybridization process, allowing its best traits in variety whilst also allowing the other varieties to contribute their best traits in combination. Once the cross-breeds are produced, then seeds from the most vigorous individual mother trees are selected based on field performance and physical characteristics; they are then propagated by harvesting shoot-cuttings and inserting them in prepared pots for subsequent multiplication.

Grown up shoot cuttings of different mother plants are then taken through field trials. It is this process which determines the field performance of individual hybrid varieties – leading to the grading such as GC 550, GC 796, GU 7, GU 8 etc.

UTRL produces various GU (E. Grandis and E. Urophylla) which perform well in cooler climates where rainfall is plentiful. GC (E. Grandis and E. Camaldulensis) hybrid clones are known to perform best in hotter climates with less rainfall.