painting or staining the wood will help.

Yes but I don’t want paint and stain getting into the veggies

how about linseed oil then.

will the linseed oil run off into the soil eventually?

No it absorbs into the wood.

Which type of linseed do you guys recommend? And how often? Thank you!

I've only used the Sunnyside brand raw linseed oil. You will need to use at least 2 coats a day apart. Follow the directions on the can.

thanks! When do you reapply?

Also is it too late to apply to the cedar raised beds? They are greying , just built a year ago.

I've never needed to reapply but I guess if the wood stops repelling water would be the time. Make sure the wood is well dry before applying. I wouldn't bother applying it to the cedar. It won't change the color and won't prevent it from greying further.

For the future, when you build another bed, what ever you use, coat the wood on all six sides before assembling. Double/ triple coat end grain/ crosscuts.

Cedar & redwood are naturally rot resistant--the heartwood, that is. The lighter colored sap wood, not so much.

Linseed oil ends up actually being food for mold so doubt that it will be of much help. FYI, boiled linseed oil dries faster than the raw version.