Gifts from donors and the Friends of Great Dixter have brought the total raised to £6m for Dixter's restoration. But Great Dixter Charitable Trust chief executive Fergus Garrett said it is vital to raise another £2m "to secure the future of Great Dixter, without compromising any of its essential character".
Garrett said: "We're incredibly grateful to the HLF and all our supporters, in particular the Monument Trust for a £500,000 grant and the Friends of Great Dixter group, which has raised another £450,000. This funding has provided the critical momentum to secure the remaining £2m of our fundraising needs."
Lloyd developed the 23ha garden in East Sussex alongside head gardener Garrett.
Upon Lloyd's death in 2006, his share of the estate was bequeathed to the Great Dixter Charitable Trust, with the other share owned by his niece.
The trust is now able to buy his niece's share and Dixter Farm. Work will then begin on a four-year conservation programme, subject to funding, with £1.8m spent converting the farm into student accommodation and £750,000 on repairing the north face of Great Dixter House.