A leading horticulturalist, Grant has worked at the trust for 23 years and previously designed an award-winning Chelsea garden, as well as penning a regular gardening column for Scotland on Sunday. He says his top priority is to maintain the trust's 70 gardens and tackle the increase in pests and diseases as a result of climate change.
Asked to describe his new role, Grant explains: "It's to set the overall strategic direction and policy creation for how we look after the gardens. Within that there will be individual garden management plans and a statement on the plant collections and how we are managing those."
Commenting on last year's reorganisation of the trust, he says: "It resulted in a 19 per cent cut across the entire organisation, but gardens took a 30 per cent cut. I think we are now at a level where we have to move forward - it's about managing change and doing things a little bit differently."
His top priority is to ensure sustainability within the gardens and to create a legacy for future generations. "We are just custodians for a very short period of time within a garden's history and we need to make sure that we are not doing anything that will be to the detriment of the garden, or make our successors' job more difficult than it should be," Grant points out.
In particular, he is keen that the significance of heritage gardens should be understood and maintained. He explains: "We undertake some garden history research to understand the significance of the gardens and we then look at how important they are in a national or European context. That helps us determine how we manage what we have got. Until we have done that, we run the risk of not preserving what we should be."
He continues: "In the past, when there was not the same attention to detail or the understanding of garden history was not so established, there was the tendency to do the gut feeling of the day and potentially destroy things that we ought to have conserved."
Grant admits that his biggest challenge is tackling an increase in pests and diseases as a result of climate change, in particular Phytophthora ramorum and Phytophthora kernoviae. He says: "These are both impacting quite significantly on some of our west-coast gardens to the extent that we are losing the heritage aspects of some of them because some of these gardens were made at the end of the 19th century, with all the species that P. ramorum and P. kernoviae love.
"If we are not getting regular hard winters a lot of pests will not get killed off and with the wet conditions there's a greater chance of diseases building up. That's probably the greatest threat.
"There has to be an element of sanitary control at a property. Like foot and mouth disease, it's for a good reason so that people are not taking the spores home on their boots - our own staff have different sets of boots and waterproofs for moving between different areas."
Despite the need to take such measures, he is positive about the future: "Let's turn a crisis into an opportunity. It gives us a chance to think again about how we might remodel these gardens. One hopes there will come a point where there will be a levelling out, but I do think we are looking at 15 to 20 years before we are in a position to establish something new and long term."
Any cutbacks in funding will result in a rethink of how gardens are maintained, he believes. "Our gardeners are very proud of what they do and are immensely hard working, and many are very reluctant to give up when they have fewer staff," Grant explains. "We have been working with staff to identify the most important areas as to whether they can manage things differently."
Regarding training within the trust, he says it is looking to rebrand and rename the Centre of Excellence in Heritage Horticulture apprenticeship scheme. He adds: "It will continue to do what it set out to do, and that's to engage programmes of garden apprenticeships in our gardens to help and, in the long term, create head gardeners for the future, ideally for ourselves."
Improving communication among the trust's membership is also on Grant's to-do list. "We need to be more open and transparent," he says. "There's a need to engage much more with membership to say: 'This is the process that we take and we are measuring success on a certain number of criteria.' That's important so we can move forward and people can expect a certain baseline."
Before he is ready to pass the baton on to his successor, Grant says he wants to "leave behind that baseline standard". He adds: "I'd like to look at whether it's achievable with our processes. We need to know what it's going to cost to reach that baseline and to reach the industry best practice."
1981-83: Certificate course, RHS Wisley
1983-84: Gardener, Brighton and Hove Parks
1984-87: Student, RBG Edinburgh, and diploma in horticulture
1987-89: Instructor gardener, Threave
1989-2009: Gardens adviser, National Trust for Scotland
2010 to date: Head of gardens and designed landscape, National Trust for