My father (without asking) unfortunately added Preen for ground covers to my large Strawberry garden raised bed. He was meaning well as he thought Preen was Preen, and that there wasn't a difference which ones can be used with consumables and which can not be.

I called the company that makes Preen and they mentioned that we should not eat any of the strawberries this year. She also said that we should consider moving the plants for next year.

Would anyone know how long it may be before that garden can be used for produce in future years, or do I need to look at removing the dirt in the raised garden and starting over?

Apparently Preen can be used on some food crops, but they aren't listed on the internet. I would read the label from one end to the other to try and see the commonalities between where/when it can be used or can't be used. Either way, the Preen should be long gone in just a couple months - next year's crop is safe.

The active chemical in Preen is trifluralin
googling for 'trifluralin herbicide label' found this
msdssearch.dow.com/PublishedLiteratureDAS/dh_08ce/0901b803808ceeb1.pdf?filepath=au/pdfs/noreg/012-10116.pdf&fromPage=GetDoc

It has recommended usages for many legumes and grain crops (not terribly relevant), but also tomatoes and orchards.

Tomatoes says:
"spray between 4 weeks and just before sowing takes place"

Orchards and Vinyards
"apply to established crops in spring after weeds ... have been ploughed into ground"

Nothing mentions interval before harvest - though obviously there would be a few months between sowing tomatoes and harvesting them. Other chemical sheets I've read have been very clear on the acceptable interval between application and harvest.

My non-legal non-scientific opinion is that the preen company is just covering their butts over something not 100% already proven safe, but you could probably even eat from this patch by the end of the summer (when you would be harvesting fruit or tomatoes), but would certainly be fine next year.

Unfortunately, the Preen product we have is one for Ground Covers. Looking at the packaging, it has a different active ingredient called S-Ethyl dipropyl-thiocarbamate. "Preen Garden Weed Preventer" seems to be a different product that has the active ingredient of Trifluralian.

I did speak with another rep from the company, and she thought that the ground will be fine next year and that we do not need to move the plants.