I have a butterfly garden of sorts. I don't really plant things specifically for butterflies, but have ended up with lots of plants that are known to be butterfly host/nectar plants. I have a feeling that there are many more in my garden, but these are the ones I remembered while reviewing a list of butterfly host plants:

Asclepias incarnata - Swamp Milkweed
Asclepias purpurascens - Purple Milkweed
Asclepias syriaca - Common Milkweed
Asclepias tuberosa - Orange Butterfly Milkweed
Asclepias variegata - Redwing Milkweed
Asclepias verticillata - Whorled Milkweed
Asclepias viridis - Green Antelopehorn
Asimina triloba - Pawpaw
Clethra alnifolia - Summersweet
Helianthus angustifolius - Swamp Sunflower
Helianthus maximiliani - Maximilian Sunflower
Lindera benzoin - Spicebush
Liriodendron tulipifera - Tulip Poplar
Magnolia virginiana - Sweetbay Magnolia
various Monarda - Beebalm
Passiflora incarnata - Purple Passionflower
Poncirus trifoliata - Hardy Orange
Pycnanthemum pilosum - Whorled Mountainmint
Pycnanthemum tenuifolium - Narrowleaf Mountainmint
Pycnanthemum virginianum - Virginia Mountainmint
over a dozen species of Quercus - Oak
Rhamnus caroliniana - Carolina buckthorn
Ruta graveolens - Rue
Sassafras albidum - Sassafras
over a dozen species of Viburnum
Vitex agnus-castus - Lilac Chastetree
Zanthoxylum clava-herculis - Hercules Club

Sorry, but I don't have pictures to post. My garden is just east of Knoxville (in Mascot, TN). Where's yours?

Wow, that's a lot of accidental hosts! There's some on your list that I'm having the hardest time tracking down. I don't have anything memorized, yet, aside the from the common names, but I have:

Asclepias incarnata
Asclepias tuberosa
Asclepias curassavica
Passiflora
Wisteria
Pipevine
Clover
Hopvine
Elm
Oak
Wild Violet
Pussytoes
Pearly Everlasting
Fennel
Parsley
Sweetbay Mag
Tulip Poplar
Wafer Ash
Wild Black Cherry
Pawpaw
Spicebush
Rue
Plantain
Snapdragon
Aster
Thistle
Purple Coneflower
Honeysuckle
and more, I'm sure
I'm in Knoxville, as well. I saw a lot of butterflies this year, here in East TN (including 4 Monarchs this fall, so far, which is the most I've ever seen). Tigers were everywhere, though I didn't get but one egg.

If you don't mind me asking, if you have any Common Milkweed, Prickly Ash, and/or Sassafras seeds/saplings, I would love to trade you for them. I'm always on the look out for these, but can never find any (same with False Nettle).

So, you didn't make it to the international plant event of the century (AKA the East Tennessee Plant Swap) here in your city? Seriously though, you could get some awesome plants there. I got two baby sassafras trees there this spring. I have some larger ones, but I wanted to grow some in specific places and hadn't been able to successfully transplant any. I have a fairly small one now that I will probably end up pulling out. It was a volunteer in my orchard and has to go. My guess is that it could only possibly be transplanted in early spring, and even then it would probably be a real long-shot. I'd recommend trying to grow one from seed or buying a very small container-grown sassafras. I know I once saw some at Stanley's over in South Knoxville.

I could easily get you some Asclepias syriaca seeds next year. They are very easy to grow from seed. I'm not sure how they'd do if dug up and divided this time of year though.

Yeah, I missed the plant swap, unfortunately. I wish I could say I was busy or something, but the truth is I just hadn't heard of it until it was over. Ijams Nature Center has a seed swap in Spring, which I plan on going to.
Stanley's is well familiar of me, don't you worry. They don't have any, though.. and haven't been able to get me any in.

Yeah, milkweeds have long taproots, and definitely should not be dug up. I tried to dig up a tiny one once (it was 3" tall), and I ended up digging 8" into the dirt, and still didn't get all of the taproot.
I really don't have much to trade.. but I'll come up with something ;-)

Adding...

Marigolds
Cuphea
Alyssum
Pentas
Salvia
Gaillardia
Campanula
Lychnis
Brazilian verbena

And that's where I had many of mine outside of the Buddleia (also great for hummingbirds and the clearwing sphynx moth), mikweed and fennel (when I had gardens. I will again, but not right now). But I also note, some I've listed can be tender perernnial/annuals (in Nashville/Shelbyville/Murfresboro where I (have) lived). Do y'all add these when it gets warmer?

Here is a link that might be useful: good list

For those of you wanting to grow Buddleia/Buddleja, be aware that it is invasive (environmentally damaging) in this area. A large area over at Ijams Nature Center, for instance, is absolutely covered over in this stuff.

Some plant catalogs (Plant Delights, for instance) say it's alright to grow invasives as long as you aren't near a natural area. This couldn't be further from the truth and is very irresponsible for them to put out to the public.

Buddleia/Buddleja isn't documented to be as much of a problem as some other invasives, but if you just go look at the Mead's Quarry area over at Ijams, you'll have little doubt as to it's environmental impact.

There are cultivars that are sterile, or near sterile. Supposedly, they are safe to plant. Apparently even their seedlings, if they have any, are also sterile/near-sterile. So, you should be able to plant these cultivars guilt free:

Buddleia/Buddleja 'Blue Chip'
Buddleia/Buddleja 'Asian Moon'
Buddleia/Buddleja 'Purple Haze'
Buddleia/Buddleja 'Ice Chip' (formerly 'White Icing')

Buddleia/Buddleja 'Podaras #4' (aka Flutterby Grande Blueberry Cobbler)
Buddleia/Buddleja 'Podaras #5' (aka Flutterby Grande Peach Cobbler)
Buddleia/Buddleja 'Podaras #2' (aka Flutterby Grande Sweet Marmalade)
Buddleia/Buddleja 'Podaras #3' (aka Flutterby Grande Tangerine Dream)
Buddleia/Buddleja 'Podaras #1' (aka Flutterby Grande Vanilla)
Buddleia/Buddleja 'Podaras #15' (aka Flutterby Petite Snow White)
Buddleia/Buddleja 'Podaras #9' (aka Flutterby Pink)

I direct Cub Scout Day Camp in Johnson City, June 6-10. I need someone to come and help us investigate butterflies and how important they are to our environment.. The date is Tuesday June 7 for about an hour or two. Help me find someone. Thanks,

Ricki