There are two large, high-intensity polyhouses at the Northern Research Station. The houses became operational in 2000.

Up to 100 grafted-ramets can be placed in each of these houses. The genotypes present within the houses originate from the breeding population, but more commonly the production populations of Sitka spruce.

Initially the 120 genotypes form the three Sitka spruce production populations (General, High Straightness and High Density) will be present in these houses.

It is envisaged that all future production population controlled pollinations will take place in these polyhouses, phasing out controlled pollination in the field, and that clonal archives will merely be used as sources of scion material.

The houses may be used to finish off the breeding work within the Sitka spruce sub-lines where possible.