Ms Berejiklian used Sunday to announce the creation of a trust to help secure the future of Wendy Whiteley's garden, a much-loved reclamation project in Lavender Bay created by Ms Whiteley on RailCorp-owned land.

The government will contribute an initial $30,000 to the trust for the garden, the immediate future of which was secured in 2015 by the granting of a 30-year lease on the land to North Sydney Council.

Ms Berejiklian's announcement is unlikely to be the only promise she makes north of the the Sydney Harbour Bridge in the next month, with three byelections for lower house seats to be held on Saturday, April 8.

Local liberal branches will on Monday select a candidate to run in the seat of Manly, and on Wednesday nominate a candidate for North Shore. Jilly Pilon, selected to run for Gosford on weekend, was praised by Ms Berejiklian as an "outstanding" candidate, but given no hope of winning the Central Coast seat.

"It is going to be a big struggle for us in Gosford, no doubt about it - I don't hold out any hope of winning Gosford but we'll be putting a million per cent into the effort," Ms Berejiklian said.

The Liberal Candidate for Manly is expected to be one of Walter Villatora, former Manly councillor James Griffin, and the chief executive of Restaurant and Catering Australia, John Hart.

Corporate affairs adviser Felicity Wilson is considered a favourite to win preselection in North Shore, though other candidates are Jessica Keane and Tim James.

A prospective independent candidate for North Shore, Mosman councillor Carolyn Corrigan, has expressed frustration with the delay in the formal issuing of writs for the election. Until that happens, Cr Corrigan is unable to raise funds to campaign.

Ms Berejiklian said she also would have preferred the writs to be issued earlier, but that was a matter for the electoral commission.

"I would love to be able to get stuck into it in a more formal sense," the Premier said. "That would have been my preference as well, but it's not a matter that I can decide."

At Ms Whiteley's garden on Sunday, once a plot of scrub that the former wife of artist Brett has turned into one of Sydney harbour's more cherished pockets over the past 25 years, Ms Berejiklian said she wanted to see the garden preserved and maintained for decades to come.

Ms Whiteley said she would match every dollar contributed by the government to the trust.

"When I head about it [the $30,000] I said, 'Hmm that's lovely, thank you very much," Ms Whiteley said. "But $5 million would be better."

"It's everyone's garden, including tourists and people who come from all over the world."