Netcraft, Barlows…places like these sell worm oil in the plastics making sections. Just a couple drops in a factory package will go a long way with keeping baits in good shape. Fleet Farm or Gander or Cabelas might have the worm oil in stock somewhere but I’ve never noticed it.
If you want to add some scent to the bait packages, just add a couple drops of scent that is oil based. You can make a cover scent using anise essential oil mixed with worm oil. A dozen drop of the essential oil will make about three ounces of scented worm oil and that mixture goes a long way….I’d add plain worm oil then a drop or two of the anise scented oil.
I’ll add here that the plastics that have been heated in water might take additional oil at and after re-packaging, so a quick check on those a couple weeks afterward might be doing good. If needed, re-oil. This is because plastics are not all the same, they’re made with similar but different components and in differing combinations. Some plastics will suck up oil like no tomorrow while others will almost weep oil from within. The plastic I use in making my baits will initially like to have a bit of oil to help get the packaging done, but if left alone in a bag will exude oil from within over time…it’s just the nature of the plastic formula I use. There are some on the market exactly the opposite.
The two big enemies of plastics are sunlight and heat and they go hand in hand. While a garage in the summer can get pretty hot, its still going to be cooler than in direct sunlight. Plastics in a garage will tolerate that sort of heat. In the boat while fishing they’ll be more likely take a warp or bad bend. Tackle left in the boat in a garage is way less likely to be harmed than tackle left in a boat open to sun day after day. [That sun will affect mono and fluoro line on reels too.] Most of today’s packaging will have some uv retardant in it to help preserve the colors and the quality of the plastics inside, so the sun’s damage doesn’t come so much from uv rays as it does heat.
If my gear and tackle get a soaking during a rain squall, I’ll spread everything out on the floor of the boat in the garage to dry. I’ll set a fan on a set to blow air across the tackle to hasten this process. Water left I and amongst ziplocks full of plastic can get past the seals and down the road the plastics can turn foggy and cloudy. Once in a while drying those cloudy baits in a room with a dehumidifier will get the color back but the next time they see humidity they’ll turn again. I try to keep my tackle storage system[5 gallon pail,lol] dry as much as possible. Those plastics with salt are a real challenge.