Dog Fennel

Note:  This was originally posted to facebook. I'm copying it here to make it more accessible.

How can anybody say anything good about dog fennel?

Dog fennel is a weed that grows from Pennsylvania to Florida and west to Texas. If you're a Southerner you've seen dog fennel. It's frequently the first plant that grows in disturbed ground. Don't replant last year's garden and dog fennel will likely take it over. A member of the sunflower family, dog fennel grows in areas where other plants just can't survive like on the edges of roads and near recent excavations. Many articles have been written by agricultural universities and government organizations about the best ways of ridding land of dog fennel.

Dog Fennel

In the first couple of years we after we moved to Florida in 2010 we were in the midst of a pretty severe drought. A lake near us, Lake Prevatt, completely dried up. It was a very shallow lake, roughly 100 acres in area but only about 3 feet deep. When it dried up dog fennel completely took over the lake bed, choking out anything else that tried to take root. It's speed of conquest of the lake bed was something to behold as the lake receded and finally disappeared.

So how can anybody say anything good about dog fennel? To understand its use you have to look at where the name came from. Many hundreds of years ago Native Americans living in the South learned that putting dog fennel in their dog pens kept their animals largely free of fleas and ticks. European settlers learned this trick and named it dog fennel -- the 'fennel' coming from an unrelated but similar looking European plant. Early Europeans also cultivated dog fennel alongside garden plants to keep the insects out of the garden.

Dog fennel keeps the insects away because of an alkaloid compound it exudes. Break a stalk and you can smell a mediciney odor. This alkaloid odor keeps away most insects. It's not quite as good as a DEET spray, but for natural compounds it's pretty effective.

I use dog fennel as a insect repellent any time I don't think the bugs will be too bad -- most daytime walks that aren't in the swamp. It's usually pretty easy to find and is always easy to apply. I put together a video of what dog fennel looks like and me applying it during a walk. The last few seconds are a picture of dog fennel in bloom (later in the year) and a range map for the weed.

So next time you forget your OFF spray and feel the mosquitos hovering reach for a stalk of dog fennel. It's probably nearby, DEET free, and will definitely deter the mosquitoes.