If you leave your garden unattended for 6 days and 23 hours from when you first placed the fence, it will remove itself and the crops along with it.
You can find the fence in a storage near to where your garden was placed.
The crops will disappear when the fence is removed and can not be restored.
So please be careful and look for the “Scheduled Removal Time” which can be found in the “Garden” icon under “Garden Information” or you can see the time removal from your map by clicking on the garden.
To help avoid this, you can reset the timer by planting new seeds.
Pruning and removing pests will not reset the timer.
As a tip, if you have the silver you can try purchasing or using Simple Processing to make Organic Fertilizer with Purified (or Distilled) water for your garden to increase its growth rate and decrease the time it will take to finish growing.