The Laskett head gardener Shaun Cadman worked at Wyevale. He bought a batch of plants from Wyevale in the 1990s and it is "still looking magnificent", Strong added.
The Laskett is now open to the public but "they like everything to be labelled, which is devastating", said Strong, who recently published Remaking A Garden: The Laskett Transformed.
"You need to take out as much from a garden as you put in, but the over-60s in particular are terrified of taking anything out. Chuck out the colour wheel and make interesting juxtapositions."
Giving plants and especially trees as gifts is "chancy, especially as the giver will want to come back next year to see how it's getting on", said Strong.
He added that "gardening, football and the royal family are the only things that hold the country together and that all parts of society care about" and "with 90 per cent of our population living in towns and cities, plants are more precious than ever".
Strong was speaking at Wyevale's relaunch. Sales and marketing director Adam Dunnett said the Earlswood, Green Line Cash & Carry, Wyevale Haskins, Wyevale Transplants and Wyevale Trees brands will "share one look".
He added:"People still think we are the same company as the garden centre chain, even though we split in the mid 1980s."
Wyevale has new lines such as Forsythia 'Spring Show Off', Escallonia 'Pink Elle' and Penstemon heterophyllus 'Margarita BOP'.
Some 22 of the staff have worked more than 25 years with the company. "They are still hungry to move the business forward," said Dunnett.