I've acquired an unfinished fir planter box. I intend to stain the exterior. Can anyone recommend a non-toxic sealant or coating for the interior to help retard rot?

I've seen recommendations for Linseed oil (boiled or raw), various Tung oil products, and about five bio- or plant-based products. I'd like to avoid urethane.

Does anyone have experience with any of these products? Thoughts?
https://gardentabs.com/plant-s...

Thanks for suggestions.

Tung oil products will do the job.

Thanks.

I would recommend tung oil. I've had experience with it an it works well for wood planters

re linseed oil, raw will eventually go rancid and boiled has lots of chemical additives these days. True boiled linseed oil you will almost never see on the shelves anymore and it's insanely expensive.