I have a separate bottle in the basement, with a few tablespoons of bleach added to keep the litter boxes clean and bacteria free. I also sprinkle lavender oil directly on the wood stairs to our basement and on the front porch!
Lavender essential oil can be very expensive, though it is worth it, I think.
I found a company that sells the most delightful lavender and other essential oils for way less than you can buy those chemical laden fragrance oils! Fifteen dollars buys 3.33 oz! In lavenderspeak that's a lot of oil! I usually buy mine by the dozen. Shipping is free on orders over $100! I also buy my bulk lavender buds, rose petals, bulk sachet pouches, cocoa butter, bath salts and many other essential oils from them. You absolutely cannot beat their prices! I used to buy my lavender at L'Occitane, but my oh my! They charge $18 for .33 oz. That is point three three!
The name of the company I buy from is Bolek Crafts Supply, nothing fancy but they are family owned and very friendly!
Because I own seven pets (they actually own me) and my husband has a home gym in the basement I am concerned about the way my home smells. I would never think to pollute the air with toxic chemical plug-ins or the like.
Every single visitor to my home remarks on how good it smells! (*dramatically wipes brow* phew!)
A few things you need to know in advance. If you make a spray bottle for your lavender you will need a spray bottle made for industrial cleaners, as the oil degrades the other type and the pump stops working. You can buy the bottles just about anywhere. I load mine up with lavender but you can use as little or as much as you like!