[2024] My plants are dying becouse of dehidration

You need containers for water. Wood buckets or glass bottles should do the trick. You can also set up the wellhouse to automatically fill containers. You can make wood buckets and glass bottles in the workshop. You can also harvest Sogweed Bulbs from the bodies of water (if they grow in your biome) and use those as containers.

Lastly, make sure you are on version 1.0.28.2 as there was an auto-job bug in 1.0.28.1 which could be keeping your farmers from creating the water plant job.