"I will be employing a gardener to make the garden fit for its intended purpose"
Thing is Tree, you're overlooking the fact that your purpose of a garden and DHE's will differ largely.
To you a garden is an area, usually to the rear of a house, used for recreational gardening activities, exercise, socialising and grazing of pets, thus generally enhancing the character of your, admiteddly rented, property.
To DHE it's the patch of land between one ****hole and the next.
Would be very interested to see what they say about emplying yourown contractors. Dripping hot tap in bathroom has been "repaired" by locally employed DHE multi-skilled "handyman" a total of four times now.
An actual plumber with even an average degree of competance would nice.