Beneficial insects are attracted to Siplhium Perfoliatum (Cup Plant) in different ways. When it rains, water is collected by cups formed from the base of opposite leaves meeting the stem. Where and when water is not available, this plant saves some thanks to its natural structure. Beneficial insects, birds, pollinators all benefit from this source of water. So if you are far away from a pond, lake, stream or other openly available water sources, consider plant this. Bees need water too! Beware of mosquitoes, however - they also need stagnant pools of water.
Cup plant is able to support red aphids without much harm. Normally, aphids are considered pests since they feed on plant sap, causing great damage to plant health. Nature does however provide aphid predators in the form of beetles - such as ladybugs. So if you want ladybugs to be around when you need them, you need to provide them a habitat with a steady source of food such as the aphids on cup plant
You should know that ladybugs have such a voracious appetite that they will even eat each other! How do we know?
One day we decided to catch ladybug larva to observe the metamorphosis. They started to disappear. We had to keep each larva in separate containers to avoid them eating each other. They eat so many aphids we had trouble keeping up. At one point, even the cup plant ran out of aphids. Then we found another plant with a healthy reserve of aphids, ran out again. Then another plant and finally we ran out of aphids. Still wanting to keep at least one ladybug larva healthy until it transformed into the family mature ladybug version with wings, we started feeding smaller larva to the bigger larva which it readily consumed.
The stem has a sturdy square shape. The plant is tall, has large leaves, and supports multiple reservoirs of water throughout its 6 foot length. This structural quality could be useful as an annual privacy screen, perhaps in two alternating rows. More interesting would be its potential for creating a temporary snow fence. After the growing season, while the cup plant is still standing, it could provide just what is needed to catch snow to create a snow drift and dune. Once that dune is formed, at the right location, you might have less snow to shovel during the winter.
Pollinators will appreciate this source of nectar in the late summer. So many plants flower in spring, so the more you can provide food sources for pollinators throughout the growing season the better.
Fall is the best time to plant. It needs the period of cold, such as winter, for the seed to break out of dormancy. Alternatively, you can re-create this period of cold, also called stratification, in an unheated garage or the refrigerator. If you do decide to stratify, the seeds will need to have some moisture, like moist soil, to avoid over drying. About one month is needed. Avoid using a deep chest freezer - that would be too cold. If this sounds like too much trouble, just plant in fall about one foot apart or less if you want to thin it out later.
Cup plant will hold its ground, spread by seed, but is controllable. Like many other plants preferred by pollinators, this plant is vigorous. Cup plant is a native perennial plant - that is, it will die back to the ground in winter but regrow from the roots in spring. It self-sows, so it can be weedy. However, you have a generous window of opportunity to cut the plant before it flowers or turns to seed. Moreover, you can't miss the plant - it is a giant among perennials. You have all summer to cut it down if it is a problem. The seed head is small and small birds seem to enjoy the seeds - a good thing if your city bylaws disallow bird feeders. Larger birds considered pests such as pigeons don't appear to be interested. Don't plant it in the middle of the vegetable garden - give it a buffer, but don't place it too far away if you want to benefit from the ladybugs it attracts.
If you are on a larger property, such as an agricultural property growing crops, it is worth growing a strip of cup plant where aphid sensitive crops are being grown - albeit in your own testing/trial setting. As Ontario's agricultural authority, OMAFRA, states, pesticide applications for the control of aphids can backfire - leading to a rebound of aphids while their predators such as ladybugs get killed by the treatment.
The height of a mature plant is about the same as sunflower - about 6 feet. Width is up to 1 foot. It needs to be well watered in spring and early summer. Full sun.