Also, it seems he was told 『Despite being a noble, why doesn’t your household employ an exclusive carpenter and gardener』, but no matter how big the mansion might be, the efficiency of employing those exclusively is bad.
A person doing that would be royalty, part of the greater nobles or a noble having gardening as their hobby. For the rest it was basic to accept the services of skillful people from the craftsmen guild.
Because the schedule of skilled artisans is filled immediately, such people aren’t very eager to become attached to a fixed place. The costs will pile up if you decide to hire them exclusively.