Jamie Moxon, 18, of Earlesmere Avenue, Doncaster was due to go on trial in front of a jury at Lincoln Crown Court but changed his pleas.
He admitted arson at the Little Lambs Nursery on Corringham Road, Gainsborough, committed with unknown other people on 9th and 11th December 2011.
The court was told that he pleaded guilty on the basis that he was not present when either fire was started but items were taken from his home by others who used them to set fire to the building.
The nursery was badly damaged in the second blaze and was forced to close for two months while repairs were carried out.
Moxon, in a basis of plea read out in court, said: “I did not attend the scene of either fire and was not involved in physically setting the fires.”
“Bottles were taken from my address which I know others used for that purpose and I did nothing to discourage the others from doing what they did.”
Christopher Lowe, prosecuting, told the hearing that he did not accept Moxon’s basis of plea but would not seek a further hearing to adjudicate the issue.
He said: “It is the Crown’s case that Jamie Moxon was involved in this arson together with others.”
“It is clear that there is evidence that more than one person was present at the scene,” he added.
Moxon was granted bail to appear back before Lincoln Crown Court later this month for sentence.
Judge Michael Heath warned him: “You can have bail on the same terms as before but you must understand that the fact that I grant you bail doesn’t mean I won’t send you into custody when you come to be sentenced.”
Speaking after the hearing Detective Sergeant Jen Waddington of Lincolnshire Police said: “These arson attacks caused extensive damage, and could potentially have endangered lives.”
“They had a severe effect on the owners of the nursery whose business was needlessly wiped out.”
“It was also shocking and disruptive for the parents who relied on the nursery for the care of their children,” she added.