"Bad growing practice" is an expression used in the commercial horticultural industry. "Bad design growing practice" could be used in the Garden and Landscape Design industry in two ways.
The Royal Horticultural Society was originally founded to promote excellence in horticultural practice for gardeners and their private gardens for long and short term yearly use.
Design for show gardens promoted by the RHS is time limited to the show opening length, or the pre determined garden life. This allows normal plant practice to be dispensed with for short term display to a degree not always realized by the public. Hard landscape is similar, designed for a short life period. The time period for walls and adjacent existing plant growth is problematical for gardens of up to 10 years growth using the show garden method.
An example of this is the 'Hot Garden' built in 2008 at Rosemoor the Royal Horticultural Garden at Great Torrington, Devon EX38 8HP.
The garden is partly surrounded by an existing high Taxus Baccata hedge. Taxus Yew is a tree with a strong root system. One low wall corner of the designed paved square required cutting hard into the existing taxus hedge root system to set out the paved square proportion of the design. The existing taxus hedge re-established its missing roots by forming mass fibre roots, the pressure of these roots on the new wall caused structural cracks in the wall two years after the garden was laid out. Nothing is done about this show garden because the garden only has a determined life of 10 years for the scheme. Bad Growing Practice in reality.
In real life the person who builds the wall is responsible in law for it, therefore the garden designer should be aware of this fact when designing the garden. The life expectancy of an existing taxus hedge should be measured in centuries.
The Rosemoor gardeners are all individually qualified to National standards. They research and choose the plant varities with colour match and contrast. The garden designer is only the spectator to this plant colour show. The designer's contribution is the paved hard standing, wall and path with paved stone edges he designed that was built in 2008. The colour photographs of planting are the RHS planting by the gardeners team.