Mary, dill and fennel may be the favorite host plants of black swallowtails, but they're practically impossible to keep alive in the Deep South. I bought some dill with BST cats already on them from the little, local nursery - if they hadn't already had cats on them, I wouldn't have bought them.
I gave the sweet nursery owner my phone number to call me whenever she gets cats on plants - she says I'm the answer to her prayers! :)
Anyway, definitely plant dill and parsley in a mostly shady spot. I asked the nursery owner if she had ever figured out the way to keep dill and fennel happy in the summer here, and she said she hadn't, and she's been gardening a long time. I planted my dill plants at the base of my Ellen's Blue butterfly bush - under the shade of the branches - also in an almost totally shaded area (only a little morning sun) under the umbrella of the gardenia bush in my garden, and the rest at the base in the shade of my big orange tree. This is about the only hope they've got.
Another thing, my plants turned yellow at the base and flopped over, too. I think it's because I watered them too much, trying to perk them up. I think their ideal situation is in cool air and well-drained soil - I don't get the impression they like wet feet.
If you have success keeping yours happy over the summer or if yours return next spring, please let us know what you did!
In the meantime, I'm growing plenty of rue. Both giant and black swallowtails will use it, and it's much easier to grow, although even rue will live longer if grown in partial sun/shade.
Sherry

Mary,

My success with the green fennel was just a fluke. Last spring I threw some old soil from plug trays (in which I had grown out various herbs) into the garden near my pipevine. Two fennel plants emerged and put up a nice display of foliage. They get dappled shade and sun in the morning. The ground is soft and has lots of leaf litter in it. We have extreme temps here. Last summer, lots of 100 degree, high humidity days. This winter, a record setting, -22. Both fennels have come back and are doing well.

Hope this experience provides some info. My thriving fennels, including a bronze one, all came from seedlings that I grew. I've planted plenty of fennel that hasn't survived. And, it feels like I just got lucky.

Sandy

I too have a time here but I find that selfwatering containers work better and seems as long as the dill has tons of water it does better I start in springin full sun and move it to morning sun in summer but seems these guys like tons of water.dill will grow with very little space I can grow them in little pots too.
Angie

I grow all of mine in full sun. I don't think I have any that grew from seed, but I have several from plants that I bought. I have both green and bronze. I keep them separated, bronze in the front yard and green in back. Mine lived all summer and several came back after our winter. They will send up new shoots. I wouldn't worry too much about floppy stems, I just leave them be. The ones that grew back, green and bronze both, don't have floppy stems :)

Older stems do tend to flop, turn yellow, and die. Mine stays evergreen in winter, and when spring comes it is the happiest, putting out tons of new growth. It likes a pretty rich soil, and I top dress it with Miss Sherry's formula - chicken manure. I do water it quite a bit as well. I grow both the green bulb and the bronze. It is not a long-lived perennial, and I usually have to replace it with new plants, or rely on self-sown seedlings for successive plants.

I find that most of the plants in the Apiaceae family do not like prolonged heat. Also, once fennel begins to bolt, the foliage growth is halted until cooler temps in the fall. Even then, it doesn't come back looking as spectacular as it did in the spring.

Both Dill and Fennel resent transplanting, so I try to handle it as little as possible, and just set it in the ground without messing with the roots at all. If you can, start it in transplantable pots, like peat, paper, coir, etc.

Dill is, for me, worse than Fennel about disliking the heat. Dill just completely languishes at the onset of hot weather, while Fennel will attempt to struggle onward.

What I have found that works best for me, is that I plant my Fennel with Zizia aptera or Z. aurea. If I have little foliage left on the Fennel, the caterpillars will wander next door to the Zizia to complete the caterpillar phase of growth. It has much more substantial foliage and while it is not their favorite like Dill and Fennel, they will do fine on it.

Zizia blooms in spring, before the Dill and Fennel. Just cut off the blooms and the foliage will continue to look fine.

I have tried to cut the flowers off the Fennel, because the wasps patrol them for cats, but it is a defeating task. It just keeps sending out more and more flowers. It is determined to bolt when it gets hot.

Susan

Yeah mine is all dying too, although I have a couple of small fennel plants that seem to be doing OK still. I have seen that fennel seems to be (although I have not had much luck with it personally) the best in the heat, compared to dill. Keep trying to get more rue going but cant do it fast enough, and even it struggles in the heat now. I am thinking about trying to grow some in pots indoors next to a window with morning sun. We have not had BSTs till late July/Aug the last couple of years but have already found a few little groups of eggs/small cats, I think we have about 20 cats/chrysalids total now. Hope we keep finding 'em thru summer this year.
kelly

Mary, I am in zone 7a, and I don't have a problem growing the green fennel or the bronze fennel in my yard. They both grow and come back without problems. I don't have any issues with flopiness either. My plants are in the ground in a dry and very sunny location. So, Sherry may be on to something with the comment about them not liking wet feet. Of all of the host plants I have offered to the Black SWT's, the fennel is their hands-down fav here.~Angie

Angie, do you live in the mountains? I noticed on another thread that you said your passionvines hadn't returned yet.
There's a lot of difference in the growing conditions in the mountainous parts of the mid/upper South and the Gulf Coastal South.
Sherry

wow, my thanks to everyone for all of this helpful information. What I wasn't very clear about is that the floppy fennel is recently purchased and is floppy in it's little 4 inch pot.

This thread just goes to show that one size doesn't fit all. We each have unique growing sites and conditions. After reading through all the great growing tips, I think I'm going to try two different growing spots this year and see how it does this summer. One spot I've decided to try the green fennel in is next to the Rosemary. It's in a protected raised bed, gets morning sun and high shade during the middle of the day. I worked up the soil real good and will mulch the plant with decaying leaves. This should help the roots stay cool and hopefully keep me from overwatering!

The other spot will get more sun so it will give me a chance to see how each growing area performs.

I do have other food for the BST cats; lots of Italian giant flat leaf parsley, curley parsley and several plants of Rue. They all overwintered well in our very severe recent winter weather and the Rue is beginning to bloom now. So I've got backup food in case I need it. I tried Dill last year and it died an immediate death so figured I'd not waste my time on that again.

This is such a fantastic forum. Thank you all so much for sharing your fennel growing experiences with me. I'll report back and let everyone know how the experiment turned out.

Mary

Supposedly, the only companion for Fennel is Dill. Fennel is allelopathic to most everything else, meaning in inhibits their growth. I've never planted it with another herb, so I don't have any experience on whether this is true or not. I have mine planted among ornamentals, like Bee Balm (well, I guess this is a mint family member), passion vines, mums, clematis. I haven't experienced any growth issues with the other plants.

But, since you said you would be growing it with Rosemary, I thought you might want to check it out. I do know that you're not supposed to plant it with vegetables because it can affect flavor of the veggies as well.

Susan

Angie, I love roasted fennel seeds on salad. I'm also a black jelly bean lover!

Would black jelly beans be licorice flavored? :(

I asked if you live in the mountains, Angie, because my passies have been up for over a month, and dill and fennel are almost impossible to keep alive here. I love the way fennel smells, too, but I don't know if it has the staying power of dill. I haven't cleaned out the black swallowtail cage (other than shaking out poop) because three of the black swallowtails pupated on the side of the cage. When I open the cage door, it smells like I opened a pickle jar!

Sherry

Uh oh, didn't know about the companion planting restrictions. I'll have to move the fennel or keep an eye on the Rosemary. The Rosemary is now about 30 inches high and maybe 24 inches across so it's a fairly large plant. The space between the two is approx. 20 inches.

Thank you for the heads up.

Mary

Yes Sherry, black jelly beans are licorice flavored. You never ate a black jelly bean??? Nowadays, they even sell little packs of only black jelly beans. Guess the black jelly bean lovers united! I think that those are only sold around Easter time tho. I guess most people don't like the black ones.Then again, PEEPS candies gross me out. :o)
I know what you mean about the Dill Sherry. It does have such a strong aroma. I like Dill pickles, but I don't enjoy the smell of Dill, and I don't like Dill as a seasoning on food.
Speaking of wonderful herbs tho, I just picked up a couple of Pineapple Sage plants from my local specialty nursery. I can't wait to plant them. Talk about a great smell. YUM