This was despite the crisis plan also saying Julian was at "extreme and catastrophic risk" if he ran away.
Ms Larsen told the inquest she had only recently started working at the home and did not know where the pond was.
In his findings into the death, released this week, Coroner Peter Ryan ruled Julian died of an accidental drowning. But he found Spectrum Care, the trust that runs Garden Court, was responsible for "two critical failings" contributing to the death.
"The first is the failure to provide a secure environment for Julian," the coroner said. "The second failure relates to staff at Garden Court not referring to and following the crisis plan for Julian."
Mr Ryan said Spectrum should train staff to follow what are now known as "emergency plans" as part of what the trust says is strengthened risk assessment and emergency planning procedures.
Previous investigations into Julian's death were undertaken by the Department of Labour and the Health and Disability Commissioner, and Mr Ryan wasn't initially going to hold an inquest.
But Julian's mum, Natasha Stacey, and her lawyer Moira Macnab kept pushing for a full account of what happened to be made public.
"It's a hearing that needed to be heard," Ms Stacey told APNZ today.
"We would not rest until we received some form of justice for Julian... I'm definitely happy with the outcome. It's what we knew as a family, but now we see it in black and white."
The "real shock" for her when the inquest evidence emerged was the amount of time it took Garden Court staff to call police.
Ms Stacey turned up at the house to pick up her son about 3pm and was told Julian, who would have turned 16 this year, had gone missing a minute ago. It turned out he had been absent for longer.
"It's a hell of a gap, a lot can happen in that time," she said.
Other new information about Julian's care also emerged, such as the number of times he had escaped before.
The side gate Julian used to get out, which could be unlocked from the outside, was replaced soon after he died, leaving Ms Stacey wondering why that risk wasn't stamped out sooner.
Ms Macnab said she hoped other similar care providers would read the coroner's findings and make sure their risk assessment procedures were up to scratch now, rather than waiting for tragedy to strike.
A statement from Spectrum said the organisation shared grief and despair over what happened to Julian and had gone to "significant lengths" to preclude anything similar happening again.
Training for the new emergency plans had been "embedded" and each person's plan was reviewed monthly.
"We take our responsibility of care and support ? in partnership with families ? very seriously and have worked actively with families to rebuild trust and confidence in the service we offer," the statement said.
"This has entailed improving our systems and security measures to manage the needs of individuals with profound disabilities and challenging behaviours. As a result, no further abscondment has occurred."