Here is the full list of all 47 Viridi achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Grow an Aeonium to maturity
Grow an Echeveria glauca to maturity
Grow a Pachyphytum fittkaui to maturity
Grow an Aloe vera to maturity
Grow a Pachyphytum glutinicaule to maturity
Grow a Pachyphytum hookeri to maturity
Grow a Sempervivum to maturity
Grow an Aloe 'Blue Elf' to maturity
Grow a Kalanchoe rotundifolia to maturity
Grow an Echeveria 'Lola' to maturity
Grow a Sedum pachyphyllum to maturity
Grow an Agave 'Blue Glow' to maturity
Grow a Kalanchoe thrysiflora to maturity
Grow an Echeveria runyonii to maturity
Grow a Cheiridopsis denticulata to maturity
Grow a Haworthia attenuata to maturity
Grow a Senecio serpens to maturity
Grow an Agave macroacantha to maturity
Grow a Fenestraria aurantiaca to maturity
Grow a Sedum morganianum to maturity
Grow a Pachyphytum oviferum to maturity
Grow a Senecio rowleyanus to maturity
Grow a Lithops optica 'Rubra' to maturity
Flower a Echeveria glauca
Flower a Pachyphytum fittkaui
Flower a Aloe vera
Flower a Pachyphytum glutinicaule
Flower a Pachyphytum hookeri
Flower a Sempervivum
Flower a Aloe 'Blue Elf'
Flower a Kalanchoe rotundifolia
Flower a Echeveria 'Lola'
Flower a Sedum pachyphyllum
Flower a Kalanchoe thrysiflora
Flower a Echeveria runyonii
Flower a Cheiridopsis denticulata
Flower a Haworthia attenuata
Flower a Senecio serpens
Flower a Fenestraria aurantiaca
Flower a Sedum morganianum
Flower a Pachyphytum oviferum
Flower a Senecio rowleyanus
Flower a Lithops optica 'Rubra'
Throw one mature plant into the garden
Throw ten mature plants into the garden
Throw fifty mature plants into the garden
Throw one hundred mature plants into the garden