i wish lavendar was the answer! unfortunately, you’ve got your work cut out for you to get rid of the fleas, but there are a lot of nontoxic ways to do it. we did the following things and have been flea-free for years (which is quite an accomplishment with 7 dogs, 2 cats, and 10 ferrets!!)
you must treat the pets, the house, and the yard.
dogs: bathe them thoroughly and repeatedly with a gentle flea shampoo, rinsing every trace of flea and flea dirt! don’t bother with flea collars or powders… mixing chemicals is a no-no! also, we feed them a high-quality food and add brewers yeast and garlic to their food from spring through summer. some people doubt that it works, but we swear by it.
house: the big trick here is to VACUUM. vacuum the carpets and all cracks and crevices in the furniture on a daily basis, disposing of the bags. every flea and egg that you suck up is one less on your dogs! although i’ve never had to resort to it, i’ve read that borax spread around the edges of your room is good for fleas (do your research first since i have no first-hand knowledge of this).
yard: i think the best thing we did was get beneficial nematodes for the yard. these are harmless, nontoxic little critters that, when spread in your yard and watered down, feed on the flea larva (the most prolific stage of flea growth). they are harmless to pets, humans, and other flora and fauna. we only had to use one application, but would do it again in a heartbeat. i also understand that diatomaceous earth is excellent for fleas, slugs, etc., but again, do your homework if you need to use this. it is nontoxic, but i believe there was something to be cautious about.
good luck in your flea fight! being consistent is the key, but it can be done!!