Something confusing, something broken, or a question about your family's garden.
Write to ayden@terryadvisors.com and describe what happened. A screenshot helps more than anything else. TerraSprout is made by a small family team, so replies are written by a person, not a queue.
They are worked out from ten years of recorded weather near you, so first check your town under Settings → Your site. If a date is still wrong for your garden, tell the app: every crop has "A number here is wrong for my garden".
Settings → Who is growing, choose the year the grower was born, and set a grown-up's code. Child mode ends by itself once they're 13. (Only the year is asked, so it can run a little past the birthday — never short of it.) There is a fuller guide for parents — ask and we'll send it.
On your phone. TerraSprout makes a daily backup you can find in Files → On My iPhone → TerraSprout, and Settings → Data → Save a copy… puts one wherever you like.
Save a copy from the old phone, then on the new one use More → Share and back up → Import a file → Replace. Your gardens, people and photos come with it.
Check the status line under the family garden: it says what it is waiting for. A phone handed to a young gardener syncs nothing at all until a grown-up takes it back, and that is deliberate.
Nothing is lost — your garden comes back. It has to be done in this order, though:
A backup carries child mode and the old code with it, so a phone restored before the new code is set comes back locked with the code you have forgotten.
From version 2.0 onwards, an older build can't open the upgraded garden and won't start. If that happens, install the newest version and restore your most recent backup.