Encouraging spiderwort growth

Right now is peak season for the flowering of spiderwort (Tradescantia ohiensis) in southern Wisconsin. This interesting plant finds a niche in the flowering sequence between the earlier lupine and the later ox-eye sunflower and pale purple coneflower. Right now spiderwort is almost the only showy plant flowering.

Spiderwort is a monocot in the Commelinaceae or spiderwort family. It grows primarily in sunny habitats, including dry, dry-mesic, mesic, and wet-mesic areas. It seems to thrive in disturbed areas, including railroad rights-of-way. At one time we had large populations growing in the railroad ballast of the Wisconsin and Southern Railroad west of Middleton, until the railroad in its wisdom did a major spraying job.

The first growing season after we cleared the large black walnut grove from Unit 18 we had a large population of spiderwort. Walnut produces a toxic chemical called juglone that inhibits the growth of other plants. However, juglone is only active against dicots and since spiderwort is a monocot it was unaffected.

Even before restoration began we also had 2 small remnant populations along the road cut above Pleasant Valley Road. We were able to encourage spiderwort spread by collecting seeds and throwing them in other parts of the road cut. Eventually we established it along our whole stretch of road. We were also able to encourage its spread by throwing seeds uphill. As the years have gone by, and with our annual burns, spiderwort is now well established throughout the whole south slope. Small populations can also be found in all our planted prairies as well as in the sunnier patches of the savannas.

On sunny days, spiderwort flowers close up by noon so that best viewing is on overcast days.

The best time to collect spiderwort seeds is when there is still a bloom or two at the top and the bottom seed pods are starting to open. Drying spiderwort seeds is a challenge. The seed pods hold lots of moisture, and getting rid of all this water is a difficult task. We have found it best to spread out the pods on plastic sleds and put them in a heated room. It might seem strange to need heat in summer, but even then, the seeds usually take four or five days to dry, sometime longer.

Some of the information here repeats material I gave in posts back in 2008 and 2011. Use the search box with the term "spiderwort" to bring up links to these earlier posts.