For over two decades I have helped people plant butterfly gardens in their outdoor space. That's enough time to hear the same questions again and again and this one has a few possible responses.
Whether you are brand new at this hobby or if you are years into it, these are some insights that are helpful to help explain why you aren't seeing butterflies.
One reason you may not have butterflies in your garden is you may not have the correct host plants. This can be approached from several angles.
For example, one time a fellow told me that he had planted milkweed in his garden several weeks ago, in the middle of our active butterfly season, and that he had yet to attract a Monarch. I knew this was not the case because in south Florida, if you have Milkweed, they will come. He showed me photos on his phone of his lonely Milkweed...only it wasn't. He had mistakenly planted another plant with bright orange flowers that, to him, resembled Millkweed. Problem Solved. Once he made the adjustment, he got plenty of butterfly action.
Another issue can arise when butterflies host on certain but not all species of a plant. This happens often with Longwing butterflies. This group hosts on some Passion Vines but not every species will work. With dozens of Passiflora spp. around, and with showy red ones being most common in nurseries, but not always the best to host a butterfly, it is easy to buy a variety that does not attract the butterflies. Even within the Longwings, each one may prefer a certain species of Passion Vine in your Florida garden. Zebra Longwings may prefer one kind, Julias another and Gulf Fritillaries a third.
Sometimes the plant is wrong for your local species of butterfly, and sometimes you are planting a host plant for a butterfly that doesn't frequent your area. Butterflies, like plants, are regional. They are highly concentrated in some areas and not in others. It is best, when planning your garden, to start by attracting the butterflies that you are certain live in your area. This is why it can be helpful for you to observe nature in your neighborhood to see what is available for you to easily attract.
On a more hopeful note, sometimes people who are new at this hobby don't know what to look for, so they are unaware that they are getting butterflies in their garden. For example, butterflies may frequent your garden when you are not looking or while you are away. If you work a 9-5 job, there is a good chance they come while you are at work and they are winding down activity by the time you get out to your garden.
You definitely know you have had visitors if you find eggs, larvae or pupae in your garden. Sometimes you only see the juvenile stages and you may miss the flying adults, but if there are babies, there were parents at some point in recent history.
Depending on the species, some butterflies have a flight season and if you search for them outside of that time frame, you are not likely to find them. Fall fliers aren't going to be plentiful in early spring. Swallowtails often over-winter in chrysalis form, so even in sunny Florida, you won't see too many of them in January or February.
There are butterflies that colonize easier than others, meaning if you have one in your garden, you will soon have dozens. Polydamas Swallowtails model this behavior well in south Florida. Once the population gets going, it's always a flurry of activity. There are other butterflies that don't ever tend to reach high numbers in your garden, Eastern Black Swallowtails are an example of this. No matter what you do, you aren't likely to have dozens of these adults around at one time.
When you read general garden books, they don't necessarily tell you these quirky facts. It takes real world experience. This is why I write regional books, specifically for Southeastern, Floridian and south Floridian gardeners, to share what isn't obvious by simply reading the generic science literature.
Hopefully, you are seeing lots of butterflies in your habitat, and if not, hopefully this post helps you get to the bottom of why not.
Keep Growing,
Jessica