Yes, you can plant seedlings or grown plants into the GrowMesh pockets.
Instructions for success;
Wash the soil off the roots and place the roots into the pocket. Some roots will be damaged when washing off the soil but the plant will be okay. It is important to remove the soil because the soil will become saturated with water and rot the roots.
Use the garden hose or kitchen sprayer over a strainer or grate to wash away the soil, You can retain the soil for starting seedlings or potting other plants.
If the root system of the seedling or plant is too large the plant may not generate enough roots to grow through the mesh.