Hillier managing director Chris Francis said since the start of the financial year garden centre sales are up 15.5% and wholesale nursery sales are up 14.5%.
Garden centre plans are to open more concessions at Eastbourne at the end of April and a new restaurant at Botley, which adds 25% more space.
He said: "We had a great autumn for weather for gardeners. We're seen as a traditional plant business so we have done extremely well with nursery stock and bedding."
Francis said the large increase in nursery sales shows how a British nursery is starting to take the "big opportunity" that Brexit-led exchange rates changes have brought against overseas suppliers.
Hillier plans to bring a lot more new plants to market, "which is where we have lost out in the last few years. We've got a bit staid. We have fantastic skill levels but we have not used them to our full advantage."
Francis added: "Hillier had a reputation for years in innovation but in the last four or five years we've lost that a bit so we need to put effort back into that."
The Hampshire business now has a £10m wholesale and trees turnover while the whole business, including its 12 garden centres, turnover is £32m.
Exporters from the eurozone to the UK have seen a 17% increase in costs, suggested HTA policy coordinator Robert Hanson in a speech at the Hillier open days, which are open to garden centre buyers this week.
Hanson said with exchange rates and plant disease threats "the motivation to source more at home has never been greater".
New Hillier launches at Chelsea include Corydalis 'Porcelain Blue', a good example of the work in the R&D department, said R&D head Kevin Hobbs.
There will also be a new tree for Chelsea, yet to be revealed.
Hillier has new stocks of Daphne 'Jacqueline Postill', with 5,000 available in 10cm pots from March 2017.
Hobbs promoted Hillier's growing of Hellebore 'Ericsmithii', IPM Essen winner Helleborus Gold Collection Ice N'Roses, Kanmara hydrangeas, Nerine bowdenii and work on Mahonia Shenii, Nothaphoebe cavalerei and Sycopsis sinensis.