Insert the trellis next to a wall behind the forget-me-not plants. Push the trellis into the ground about 1/3 of the total height of the trellis to ensure it won't fall over.
Select the longest of the forget-me-nots' stems in the late spring or early summer. These will grow up the trellis.
Secure the young shoots of the forget-me-nots to the trellis. Tie twine loosely around the stems to hold them in place.
Allow the forget-me-nots to grow throughout the season. Tie more stems to the trellis as they grow to ensure the plant grows up the trellis, and not out.