My Wetland Container Planting

My Wetland Pot 8/16/19

Eryngium aquaticum

Eryngium integrifolium

I have posted several times about my created wetland that uses a pond liner to prevent water from soaking into the ground. I capture water during rain events from my downspout and direct it into this area. The soil stays saturated during wet times and rarely dries down to the point that it needs extra watering. The plants in this area are doing exceptionally well and it has allowed me to grow a number of species important to my landscape objectives. It is, for example, a perfect place for my 2 species of wetland milkweeds and my water dropwort (Tiedemannia filiformis). The latter is now starting to bloom and soon will attract the attention of eastern black swallowtails.
Today, I wanted to post an update on my "other wetland" - the large landscape pot that sits in a black plastic pool. This is a different kind of wetland as it is meant to stay saturated. Rain events fill the pool and this water sits above the soil line when the pool is full. I sited this pond in a sunny corner of my yard and I'm growing a few species of wetland plants that appreciate these conditions. When the rains don't occur over any appreciable time, I can fill the pool with my hose. I've had to do this periodically - more to keep the animal life alive than the plants. The water breeds frogs and toads. It also attracts the attention of dragonflies.
When I first posted about putting this wetland in my landscape, I heard from several people who wondered about mosquitoes. They are a concern, of course, but I find that they can be maintained by occasionally adding a "mosquito dunk" to the water. These kill the mosquito larvae, but I've seen no evidence that they harm the other animal life. The water is full of tadpoles and the dragonflies surround the pond. I haven't made an attempt to search for their nymphs.
If we are to create a living landscape, it seems to me that we need to create as much diversity as possible. I've never had the opportunity to live in a landscape with a natural wetland, so I create my own. This pot is a very simple approach that costs very little and can be moved easily if needed. This is the same pot and planting that I had in my previous landscape. I moved it and it continues to prosper here in my new home.
Space is limited, however, so I've planted it with button snakeroots.  Both of these blue-flowered Eryngiums are quite robust and would crowd out my other wetland. They are confined here and they spread inside the pot - fighting for dominance with each other. Eryngiums are in the carrot family, but most do not serve as host plants for the eastern black swallowtail. Neither of these do, but they are superb nectar sources for pollinating insects. Soon, these heads of tiny powder-blue flowers will be covered by bees and butterflies. I am growing another such species - Eryngium yuccifolium - in my nursery right now, but it won't need such wet conditions to thrive.
The above photos show the difference in the flower heads. Though both produce much the same color flowers, E. integrifolium has much smaller bracts below the head than E. aquaticum does. Both the bracts and the flowers will turn blue shortly. The foliage also is different. E. integrifolium has narrow strap-like basal leaves while those of E. aquaticum has leaves that are noticeably wider. In the first photo, you can see this difference. E. aquaticum is on the left hand side while the other is on the right. 
The pot also contains a pine lily (Lilium catesbaei) that I've had for at least 3 years now. It has a flower bud once more under these conditions and should bloom in about a month. You don't have to "live with" the growing conditions you are naturally given on your property. Wetlands are important and provide the types of conditions that a wealth of important plants require. These plants, in turn, provide habitat for a number of interesting and important wildlife species. If you don't have a wetland, I encourage you to make one. Mine are both developing nicely.