In her closing remarks she said Labour would push up taxes and bills.
“These are hard truths but better face them now than regret them later… don’t give a blank cheque to Labour.”
The debate took place on the same day as Labour launched its manifesto, which promised to boost growth in order to fund public services.
Ms Rayner stressed her party’s message, saying it would deliver growth “in every corner of the country”.
“Why so timid, why wait for growth?” the Greens’ co-leader, Carla Denyer, asked as she urged Ms Rayner to adopt her party’s plan to increase tax on the wealthier in society.
She said the Tories were “toast” and accused Labour of offering the “same broken politics dressed up with a red rosette”.
Labour’s deputy leader also faced criticism from the SNP’s Stephen Flynn.
He said it was “shameful” that Labour was not committing to re-joining the EU.
He also accused the party of accepting £18bn of cuts to the public sector.
Plaid Cymru leader Rhun ap Iorwerth expressed surprise that Labour was not promising to get rid of the two-child benefit limit, while Mr Farage appeared to back it.
“What’s happened to the Labour Party?” he asked as he argued that the cap damaged the poorest families.
Ms Rayner said her party would not commit to “unfunded” policies and pointed to Labour’s plan to provide breakfast clubs for children.
Questioned on the cap which restricts some benefits to the first two children in a family, Mr Farage said: “I think we should encourage people to have families.”