They fought off competition from more than 600 organisations to reach the public voting stage, with both competing in the Environment category.
The winners of the seven National Lottery Awards categories will each get a £3,000 cash prize to spend on their project.
Grow Wild Project is involved in more than 80 youth and community projects in Scotland. Around 175,000 people have been sowing native wild flower seeds in Scotland after requesting a free seed kit from the organisation, which is based at RBG, Kew.
The Great Trossachs Gateways Project will benefit the UK's largest National Nature Reserve in Loch Lomond and the Trossachs National Park. Lottery funding has enabled the creation of a connected mosaic of native woodlands and upland habitats and delivered new visitor facilities.
Also in the Environment category are Blooming Beds and Bees - a community gardening project created in Tottenham as a response to the 2011 riots - and WildPlay, which has helped create attractive green spaces on housing estates.
Votes can be cast at www.lotterygoodcauses.org.uk/awards.