The Danish brand's Botanical Collection consists of two sets, both featuring snap-together components derived from sugarcane.
Flower Bouquet contains elements to construct bunches of model flowers and grasses while the pieces in the Bonsai Tree set combine to create a miniature tree with optional blossom.
Kits to build individual roses and tulips are also available.
"As adults look for new ways to switch off and relax, we saw an opportunity to help them switch off after a busy day and relax as they immerse themselves in creating these beautiful botanical builds," said Lego senior designer Anderson Ward Grubb told Dezeen.
Lego launched the collections as many people are spending extended periods of time at home due to the coronavirus pandemic. The completed models are intended to be displayed in the home.
"Our homes have always been the most important spaces in our lives, and that's only become even more so as many of us find ourselves there for longer periods of time than we're used to," explained Grubb.
"So, it was critical for us during the design process to create products that were not just fun to build but were beautiful pieces of decor that you'd want to have on display and bring you a bit of that focus and joy you felt as you put them together."
Designed to allow users to create varied arrangements, the Flower Bouquet set contains 756 pieces that can be used to build flowers including roses, poppies, snapdragons, asters and daisies, along with several different types of grass.
The bonsai model building kit contains 878 pieces to create a tree that is displayed on a rectangular plant pot on a slatted wood-effect stand.
Both sets were designed to be customisable so that users can build there own individual creations.
The bonsai tree can be built with green leaves or pink cherry blossoms, while the flower bouquet has adjustable stems and pieces in new colours and shapes.
"We wanted to be sure people could make these pieces their own, so we made the flowers adjustable so they would work in different arrangements, and the Lego Bonsai tree can be customised to be in a normal green or blossoming pink," said Grubb.
"There is so much joy to be had in arranging your own bouquet, whether it's adjusting the positions of petals and leaves, adjusting the lengths of the stems, or seeing how each combination of flowers sits together until you've got it just the way you want it."
Currently, bioplastic bricks only account for a small amount of Lego's output, but the company's aim is to produce all of its bricks from bioplastic by 2030.
Grubb hopes that the Botanical Collection will bring families together and introduce Lego to new audiences.
"Over the past year, we've seen more families building together to help them get through lockdown, and many adults have also started building with Lego bricks for the first time," explained Grubb.
"Lego building can provide new ways for adults to explore their passions as they engage in a mindful activity," he continued. "We want to provide sets that adults with a wide range of different interests want to build before displaying proudly in their homes."
Plastic bonsai trees are not new to the design world. Last year Japanese design studio Nendo created a 3D-printed bonsai tree called Grid-Bonsai that owners can prune to their liking.