Hibiscus grandiflorus in the Cold.

In 2010 I had posted several reports on Hibiscus grandiflorus seeds I had purchased from NWN Nursery - Foster Folly in Chipley, Florida in the fall of 2009.
http://davesgarden.com/products/gwd/c/1826/

The Hibiscus grandiflorus seeds were started indoors without any difficulty. When I put the plants out too early in the spring of 2010 all but one plant was killed by a late frost. The survivor grew a single stalk which flowered and set seeds; the seeds were collected and saved. I posted a picture of one of the flowers here;
http://davesgarden.com/guides/pf/showimage/308992/

With the onset of winter I covered the Hibiscus grandiflorus with one foot of salt-hay and expected the Hibiscus to not make it through the winter in my Zone 6b garden.

Much to my surprise in the first week of May 2010, I discovered that the Hibiscus grandiflorus survived the winter 2010-2011, which set record snow falls in New Jersey, and appeared to be sending up four new stalks. The winter of 2010-2011 saw snow coverage of three to four feet all winter.

I did not remove the single stalk from 2010 which is 50 inches tall so that I would have a point of reference for the four new stalks. As of June 5, 2011 the new stalks are 40 inches tall and the fastest growing Hibiscus in my Zone 6b garden and can be viewed in the attached photograph. I have no explanation as to why a Hibiscus grandiflorus, native to Florida, is doing so well in New Jersey.

Plant Delights (http://www.plantdelights.com/) reports that their Hibiscus grandiflorus cultivar would survive to Zone 6 but I had assumed that they had an unusually cold tolerant cultivar or the claim was wishful thinking on their part. Apparently some or perhaps many Hibiscus grandiflorus are more cold tolerant than is realized. I did save seeds from 2010 so if anyone is interested send me a DM. I also have some interesting hybrids with other Hibiscus species but am still waiting to see how they turn out.

As anyone had any experience with Hibiscus grandiflorus surviving in cold Zones of 7 or less? Was any special action required?

Mike

Mike, i am in zone 5A and mine have survived for about 50 years and are doing fine. I live in southwestern Michigan and we get the heavy Lake Effect snows and temps below freezing. I think the best part about the plants is that they die back each fall and the root system is protected by the ground. I collect the seeds in the fall and in early spring I trim off the stems from last year and get ready to enjoy the summer show. The colors i have are dark rose, light and dark pink, and white with a red throat.

Annabelle15

That is an unusual color range for H. grandiflorus flowers. Can you post some pictures or take some pictures this summer and post? Do you know what the history of your H. grandiflorus is? What was the source? Over the last 50 years have you started new plants from seeds, root divisions or stem cuttings? During that time, has there been any change in the color of the flowers?

My H. grandiflorus are directly from Florida and the color of the flowers are unremarkable for the species. I have sent seeds to several DG members and have a number of new plants started from seeds. While I am going to protect the original plant, I plan to overwinter several plants without any protection this year.

Mike

the mother plant belonged to my Grandmother, my Mother took seeds from it in the 1950's and mine (I live in the house my dad built in 1942)
and all of the ones that she planted are still going. I thing as they bloomed and set seed, there was a few mutations and that is the reason for the color differences. I will try to get some pics on the site as soon as they bloom. P.S. anyone need seeds, I have a lot....lol