Cold Hardy Hibiscus Tips For Gardeners And Gardening Professionals:
Hibiscus are perennial plants which thrive in cool climates. They grow well in temperate zones 3 through 9, but they will not survive extreme cold temperatures.
However, there are some exceptions to this rule. These include:
Zone 5 – Hibiscuses do not like extremes of heat or cold, so these types of plants may survive colder than freezing temperatures without any problems.
Zone 4 – Hibiscuses can tolerate temperatures down to around 20 degrees Fahrenheit (Fahrenheit). If your plant survives at such low temperature, it will likely survive even if the surrounding area gets into the negative range.
Zone 3 – Hibiscuses cannot handle very cold temperatures. These types of plants may not survive temperatures lower than zero degrees Farenheit (-40 Degrees Celsius) for long periods of time.
The only way to ensure survival of a plant in colder weather is to provide adequate shelter from the elements. A good place to start would be with a heater.
You can purchase one online or you can make your own DIY heater using old clothes dryer sheets, plastic bags, and other materials. Place the sheeted or bagged material over the top of your potting soil and cover with another layer of potting soil. This method will allow the roots to still grow naturally while protecting it from harsh cold winds.
If you do not have soil, you can also use small greenhouses or even Styrofoam coolers. These types of items are perfect for plants that thrive in cooler weather as they trap the necessary heat while still allowing a bit of “breathing room” for the roots.
If you are handy, you can also build something similar using mostly recycled parts.
The general rule of thumb for planting zones is that you add one to the lowest temperature in your area to determine the first zone. For example, Utah County in Utah has a record low of around -20F.
The first hibiscus planting zone for this area is therefore zone 1 with a minimum average of 0F.
Hibiscus Growing Zones By State
Hibiscus Growing Zones By State
Alabama – Zone 6
Alaska – No plantings
Arizona – Zones 3,4,5,6,7,8
Arkansas – Zones 5,6,7,8,9
California – Zones 3,4,5,6,7,8
Colorado – Zones 1,2,3,4,5,6,7,8,9,10,11
Connecticut – Zones 3,4,5,6,7
Delaware – Zones 4,5,6,7,8
Florida – Zones 8,9,10
Georgia – Zones 5,6,7
Hawaii – Zones 1,2,3
Idaho – Zones 1,2,3,4,5,6
Illinois – Zones 4,5,6,7,8
Indiana – Zones 4,5,6,7,8
Iowa – Zones 4,5,6,7,8
Kansas – Zones 5,6,7,8,9
Kentucky – Zones 4,5,6,7,8
Louisiana – Zones 3,4,5,6,7
Maine – Zones 3B,4B,5B,6A,6B,7A,7B,8A,8B
Maryland – Zones 4,5,6,7,8
Massachusetts – Zones 4B,5A,5B,5C,6A,6B
Michigan – Zones 3A,3B,4A,4B,5A,5B
Minnesota – Zones 3A,3B,4A,4B,5A,5B
Sources & references used in this article:
Our hardy Hibiscus species as ornamentals by HF Winters – Economic botany, 1970 – JSTOR
Hibiscus plant named ‘Crown Jewels’ by DW Fleming, GA Zwetzig – US Patent App. 09/289,836, 2001 – Google Patents
Hibiscus plant namedPink Wonder by WL Morrison – US Patent App. 08/434,587, 1996 – Google Patents
Breeding and genetics of lilacs and hardy Hibiscus by J Lattier, JD Lattier – 2017 – ir.library.oregonstate.edu
Hibiscus plant namedKopper King by DW Fleming, JR Fleming – US Patent App. 08/963,542, 1999 – Google Patents
Hibiscus plant named ‘Whit XX’ by C Whitcomb – US Patent App. 10/693,073, 2004 – Google Patents
Cold‐acclimation of Hibiscus rosa‐sinensis L. and Hibiscus syriacus L. in natural and controlled environments by TM Teets, RL Hummel, CL Guy – Plant, Cell & Environment, 1989 – Wiley Online Library
Hibiscus plant namedRoyal Gems by DW Fleming, JR Fleming – US Patent App. 08/962,866, 1999 – Google Patents