Second Test Strip Launched

We finally have the second test strip on the roof.

(Planted November 7)

This strip has deeper media (8”), and is planted with a Muhly Grass, Cordgrass and Equisetum, all native plants. We chose these plants because they are native and can take both drought and inundation in water. According to other studies that we’ve looked at, you need at least 6” of planting media for grasses. The Key West green roof only had 4” of media and this may have been part of the problem (See Key West Brown Roof). My hypothesis is that the grasses will do well but that the strip will become root bound quickly in the 15” x 30” planter, and that larger planting areas are required for grasses. We’ll report on this strip monthly with the original strip.

Death on the Roof

Not a happy report this month. The perennial peanut has passed away and the mimosa strigulosa took a dive but appears to be coming back. The bulbine looks a little stunted but has several blooms.
Why did the perennial peanut and mimosa perish? What could have caused so much damage after not only surviving, but thriving through two months of brutal heat? There was plenty of rain so it couldn’t have been drought. We checked to make sure that the drainage was working and it is, so they didn’t drown. The perennial peanut is supposed to fix its own nitrogen so it couldn’t have been a nutritional deficiency. There are two possible problems that I can determine. Please write in if you think it is or isn’t one of these factors.
Even though both perennial peanut and mimosa strigulosa live in cooler areas than here, we had a record low in October. Unfortunately, we didn’t check the temperature on the roof, but the ground temperature was in the 40’s. While both plants should have survived 40 degrees, maybe the planting media (lava rock and peat) is unable to hold any heat and the low temperatures were cold enough to damage the plants. The perennial peanut and the mimosa were planted on the ends of the strip so it may have been colder than the middle location where the bulbine is.
The only other possible causes that I can think of could have to do with the test strip construction (the sides ended being slanted as the pond liner shrunk a bit, or, there could be some type of nutritional dysfunction because of the planting media we picked.
This leads to a thousand other test strips that we would like and should try, if only we had time and money. Any leads on grants? Testing different planting media, planting media depths, and more plants, especially native ones, would help to ensure that we could reap the many benefits of green roofs in South Florida.

Willow Queen

My husband now calls me the Willow Queen. I guess it could be worse. I have been wandering muddy areas around Jupiter getting willow cuttings. It started with a park we are working on with Glatting Jackson in Boynton Beach. We wanted to provide sensory experiences with plants and came up with willow tunnels as a good way to provide green play things. Of course, it hasn’t been done in South Florida. All of the information we could find on the web came from England. You can actually order live kits for a variety of willow constructions. Unfortunately, the willows that live in England do not live in South Florida.

While there are probably a large number of plants that would work, coastal willow is native to South Florida and we decided to try it. Unfortunately, local nurseries don’t grow many Coastal willows; we could only find two trees in our area.

The RFA team planted the two store bought willows 5’ apart at Terracon Services out in Jupiter Farms. (picture above) These willows can become stock and will also allow us to at least tie together and braid some taller established willows. We also grouped some cuttings we made in groups of three and planted them in three gallon pots in the garden area behind our office. They rooted quickly and easily and we hope to plant them somewhere close by so that we can keep an eye on them as they grow and start the braiding process when they get to be about 4-5 feet tall. We’ll post quarterly pictures once they are planted in the ground.

Sprouted willows ready for transplant.