Complex sentence: Schuch established the first fruit tree nursery in Poland there, where he experimented with various novel methods of protecting the trees from excessive sun and frost, until an abnormally harsh winter of 1802/3 caused a substantial financial loss.
Split into simpler sentences: Schuch established the first fruit tree nursery in Poland there, where he experimented with various novel methods of protecting the trees from excessive sun and frost. However an abnormally harsh winter of 1802/3 caused a substantial financial loss.