The plant centre is located on the same West Midlands site as Earlswood Nurseries, the hard landscaping specialists.
Earlswood Plants managing director Alan Standring said: "If the weather is as nice as last weekend then we are hoping for 600-700 people. We have done a trial opening since February and it seems to be working very well; business has been fantastic. Earlswood is a very strong hard landscaping business and we are just trying to tag along with that."
Biggs will be on site to give six short talks throughout the day, discussing his favourite plants, including Japanese Maples.
The development was finished in February and includes a new plant area and glass house.
The outdoor area is now stocked with a full range of garden plants including alpines, herbaceous perennials, fruit and ornamental trees, fruit bushes and shrubs.
Most of the plants are sourced from the company's production nurseries in Herefordshire with specimens coming from Tuscany.
The major development on the plant area includes the installation of a shaded canopy area and Venlo style glasshouse.
The wholesale side of the new development will officially open later this year, under the name Greenline Plants.
Greenline Plants will operate through the same site, offering the trade approximately 30% discounts on retail prices.