The centre opened a year ago, but roadworks nearby meant the £25m, 20-unit retail park's tenants struggled to meet sales targets.
Olley said: "It was a fantastic opening that passed all expectations, but roadworks to put in an extra 25 per cent capacity on our roundabout meant we had to endure a bit of pain.
"It does mean that the first year has been tough. But since autumn, Van Hage has been bedding down. Week on week it's getting better and gaining real traction."
Dobbies hopes to open an £8m centre in Peterborough later this year, but Olley said Van Hage had a "different offer", although "it might mean smaller centres in Peterborough have a tougher time". The park is currently 84 per cent let.
Another Garden Park Investments site in Andover, Hampshire, is now set for residential or retail use other than the garden centre originally mooted.
But Olley said: "We have the scheme so planners can see what we're about. We're not so actively out there as a couple of years ago, but there are two other schemes we're looking at."