New plants sometimes need an adjustment period from the time they leave the greenhouse to being planted in the garden.
This is referred to as 'hardening off'.
Viola can be planted in full sun or partial shade locations.
If the new plants did not have time to adjust to a bright location they may droop and wilt.
Make sure you are providing even watering until the plants become established.
The soil should be moist but not soggy. New tender roots that dry out may not survive.
Here are some articles with more information.
https://www.gardeningknowhow.com/garden-how-to/seeds/how-to-harden-off-your-seedlings.htm
https://www.gardeningknowhow.com/ornamental/bulbs/violet/types-of-violets.htm
https://www.gardeningknowhow.com/ornamental/bulbs/violet/johnny-jump-up-flowers.htm
