The grower has moved from its original Nuthurst nursery site to a 14ha site near the Brinsbury campus of Chichester College.
Those attending the event, which will include a private guided tour of the new site as well as afternoon tea, will also be treated to an exclusive talk by guest speaker and celebrity plant expert, Tom Hart Dyke.
He will be answering questions about gardening and talking about his experiences, including creating the UK’s first ever ‘World Garden of Plants’ at Lullingstone Castle in Kent and of his kidnapping in the Colombian jungle in search for rare orchids.
Hart Dyke said: "I am thrilled to be part of Architectural Plants official launch event. I have dedicated my life to plants so it is important to me to support companies that share my passion. The event will be a great opportunity to discover all that the company has to offer and provide a fantastic platform for those keen on gardening to ask both the experts at Architectural Plants and myself any questions on how to look after your plants, maintain your garden and any other gardening design queries."
A charity auction to win a specialist Niwaki Tree will also take place raising money for Streetscape, a charity that provides apprenticeships in landscape gardening to young people who are long term unemployed.
Angus White, Founder of Architectural Plants, said: "Twenty five years ago I started Architectural Plants as a bit of a hobby and twenty four and three quarter years ago, I realised we needed to move to somewhere more suitable.
"The new site near Pulborough is my dream come true. It's huge and we are very excited. Featuring a two acre lake, it offers tremendous opportunities for architectural follies in the shape of jetties and boathouses, mighty timber and galvanised steel structures with red and white life-belts - all beset with shapely, spiky and pointy architectural plants.
"We are really looking forward to the official launch with Tom Hart Dyke as it certainly marks the start of something new for us here at Architectural Plants. We wanted to extend the offer to members of the public so they too are able to enjoy the exclusive event and be inspired."
Limited tickets are available and those interested in winning a pair of tickets to the official launch party are invited to enter a ballot by emailing email@example.com The ballot will open on Thursday 1 January and will close on Sunday 8 March.