Gardening videos often concern a specific stage rather than an entire growing season. The thumbnail should show the plant condition or task that viewers will actually learn about.
Select the stage
Choose a frame representing sowing, transplanting, pruning, or harvesting as appropriate. A lush mature plant may imply a result that a seed-starting video does not demonstrate. If showing an outcome for context, make that relationship clear.
Reveal the useful detail
For pruning, show the branch structure and the intended working area. For transplanting, the root ball or pot size may be more informative than a distant garden view. Keep hands from covering the feature being taught.
Review accuracy
Check plant identification and any added labels. Avoid a transformation layout that suggests immediate growth when the footage spans a long period. Preserve dated source photographs in your project so the sequence and conditions remain understandable when the thumbnail is revised later.