Hands could not talk about the sale of Dobbies, which Terra Firma is expected to buy before the EU referendum, and the private equity company has also refused to comment on rumours it might buy Notcutts Garden Centres, which also declined to comment.
On the potential Brexit, Hands said: "For the UK, the cost of plants will definitely go up. So many of our plants are imported from Europe and at the moment we rely on the quarantine system and freedom of movement, which that quarantine system allows. If we came out of Europe we would have to put all regulations in place separately.
"A lot of people think coming out of Europe could get rid of regulations but in reality we would have to recreate a whole lot of new regulations instead of having a certified regulator, which we might feel is excessive, but we'd end up with lots and lots of individual regulations, many of which would be equally excessive."
Terra Firma head of portfolio businesses Justin King added: "It is impossible for us to see how there could be an exit without an impact on prices and inflation. It would probably mean further depreciation of the pound, driving up the price of imported goods for consumers."
Elsewhere at Chelsea, suppliers were generally in favour of staying in the EU. Briers managing director Jackie Eades said: "I worry about the exchange rate and trade barriers that will go up, and even travel. We do a lot of exports so it would be a nightmare. There's a cost of being in Europe but the unknowns could be more damaging."
Plants for Europe director Graham Spencer said: "I don't think the British industry could supply without European young plant supply. We don't have the capacity. That capacity is going to be offshore somewhere. The Government has to invest more in plant health to make the European supply chain work and make sure people have more confidence in it, because one of the arguments for Brexit is it would improve biosecurity. But we can make it work better by working with European colleagues and investing in it."
Hillier wholesale and retail director Chris Francis said: "My view is it would be an unsettled period that would make it difficult for us as growers and retailers."
But Town & Country chief executive Barry Page said: "I'm voting out because the EU is unconstitutional, unaccountable and undemocratic."
- Ornamentals growers are urged to join the Brexit debate and complete Horticulture Week's short survey here.