Request for Persimmon Ripening Data

Invitation for Persimmon Ripening data


You are receiving this solicitation because I am inviting your assistance this fall in an effort to compile data for the earliest ripening persimmon varieties. Should you desire to assist, please keep accurate data as you harvest your persimmons this fall so that we can form a consolidated reference that should benefit any prospective grower who has little knowledge about persimmons to select varieties most likely to ripen in areas with shorter growing seasons.

I have invited and received considerable input from forum members and several nurseries who have experience and I have begun to compile a summary of only those particular varieties by zip code location. The data I have collected so far only gives some idea of the relative time of season that a given variety ripens, often in reference to other varieties. However, the data in most cases can be linked to a zip code which facilitates comparison of the climate where ripening occurred to other zip code locations. Most likely there are other varieties that would be good candidates for this list which I am inviting members to provide. Meanwhile, I am asking forum members to give me validation data this fall for their respective varieties and to confirm zip code locations as they observe ripening data to update my current list of varieties. I will then use this data to update my reference with more precise data.

The reason I would like to create such a database of known varieties is that there is a desire for such data by members, residing in cooler and maritime climates, who could benefit from reliable data from others who have experienced success.

The case for better data is clear! Persimmon trees require several years once planted or grafted to actually begin production. Only then after several years would a grower be able to determine if a chosen variety will actually ripen. Although the climate zone may support persimmons from a plant growing and survival perspective, unless the geographic location and microclimate provides the length of growing season, and the degree days of heat and solar radiation required to actually ripen the fruit, one could plant a new tree, grow it for 3-4 years only to discover that the perfectly mature fruit it produces will not ripen before the onset of winter. How often do we read about such disappointing outcomes after investment of time and resources by members who possess little experience with persimmon varieties.

While plant Nurseries do provide some advice on suggested growth zones, they often do not have the specific information to determine if any particular variety of Persimmon will actually ripen its fruit. Moreover, in spite of numerous articles on growing persimmon on the web, rarely does one provide a calendar reference or zone map that is oriented to ripening potential for each cultivar. As our society turns to data driven decisions, there is no known database for determining the ripening potential for various persimmon cultivars. Thus, the need for one to be created as I am proposing. The data is there, in the experience of forum members, but has not yet been collected and compiled in a useful, reliable reference.

As I have researched the subject there appears to be numerous named varieties and hybrids that have been developed in northern climates, but it’s very difficult to ascertain their time of ripening and the climate by zip code so that one can make an efficient and accurate climate comparison to determine ripening potential for another location. The same is true for Asian varieties.

So I am prepared to collect and compile a reference using the data I obtain from forum members, who are willing to provide reliable data on any particular persimmon cultivar (Asian, Native, or Hybrid).

How future members can benefit from data collected:

Once the below key data is compiled and shared with interested members it would be feasible for any member to more accurately determine if any particular cultivar, that has been reported to be successfully ripened by a fellow member, may be suitable and have good potential to actually “ripen fruit” in another geographic location by comparing weather data and average daily temperatures of the location of the reported variety to any other potential locations. By comparing the cumulative growing degree days above a certain base temperature between the known location (location where growing and ripening successfully occurred) and any potential new location (where the cultivar is desired) a member can assess a variety’s potential. The following free website can be used to obtain the cumulative degree days above the base growing temperature for Persimmon which is typically accepted to be 70 degrees.

Note: Since most experienced grafters on the forum have noticed that the potential for grafting success in persimmons occurs when the ambient temperatures are sustained above 70 F degrees, It is suggested using 70 F as the base temperature for Persimmon. Using this base in the formula on the following website one can generate the degrees days that were actually required for the current year for ripening to occur.

By comparing the growing degree days of the reported location with the growing degree days of a potential site, a statistical assessment of potential success. at the new location is obtained.

This comparison should be based on data generated within the same timeframe for the actual reported data and the desired growing sites.

The below website is suggested for its ease of use, simplicity and its applicability anywhere within the US. To utilize this website to estimate growing degree days, always use the “Cooling” button rather than heating to capture the actual growing degree days data above the base temperature.

Steps to use website:

  1. First select the weather station in your zip code ,
  2. then select “cooling” under data type,
  3. then select “weekly” under Breakdown,
  4. then under Period covered, choose the number of months since your region experienced maximum temperatures exceeding your “base temperature”,
  5. then Click on “Generate Degree Days “ icon.

Once you have completed these steps, the calculator will generate a spreadsheet showing the data for the weather station chosen. One can then repeat the same process determining the degree days for any other zip code where a known persimmon variety has been shown to successfully ripened. By comparing the two data sets, a realistic assessment of the variety’s ripening potential in the desired location can be made.

NOAA heat map: Average Monthly Temperature | NOAA

NOAA 30 year normals: 1991-2020 U.S. Climate Normals Quick Access: on this site you can obtain the annual chart of min, max and average temperatures each month to compare with other zip code locations.

This map can quickly be used to compare one region to others.

The reference I intend to create would include the following information each year as new data arrives from forum members. So I hope it can be a living document as new varieties show promise. If you are willing to participate please save the following Submittal Request details and submit to me once your harvest is completed.

Submittal Request

Source: This would be the member’s forum user name. For example my growing user name is @Dennisd. Other forum members can use this information to contact the source to ask any relevant questions. If for some reason you do not wish to be contacted, but you are willing to provide data, just let me know and your Source will be listed as “Anonymous”.

City: Large City near the Source of data. (Necessary to locate nearest weather station to compare growing degree days between any two geographic locations.

Zip code: Enter the zip code of Source . (Necessary to locate nearest weather station to compare growing degree days between any two geographic locations.)

Variety: Persimmon cultivar name: This would be the specific name of the cultivar for which the data applies.

Astringent vs. non-astringent: Enter applicable type

Rootstock: Enter the rootstock name (D. Virginiana, D. Kaki, D. Lotus, or Unknown if you are uncertain)

Age of Tree: Enter the number of years the tree has grown if known, or the approximate age if not known.

Date: (Month/Day/Year) The first date when fruit was ready to harvest.

Duration of harvest: Enter the number of days from start of harvest until all fruit was ready to harvest.

Condition of fruit harvested: Describe whether the fruit could be consumed immediately after picking or if it required additional time and/ or procedures to fully ripen before consumption or any special treatment to overcome astringency.

Applicable Microclimate: Enter N/A if the tree variety reported was growing naturally in an ambient outdoor location. In a situation where the grower provided any support methods that would improve the growing degree days, such as inside greenhouse, solar tent, shelter, heat absorbing wall, wind protection, State briefly the improvements provided.

Relative Climate difference: State whether there is a significant difference in the micro climate between your reporting location and the nearest weather station in your zip code. For example an altitude difference should be annotated.

Please let me know if you would like to assist me in this endeavor, and if you know another persimmon grower in a northern cooler region who might also participate please pass this notice on. Once you are ready to submit your data, Please PM me to obtain my direct email address


Dennis Dowdy

Kent, Wa 98030