Since a fair number of forum members have an interest on finding a way to determine in advance which Persimmon cultivars will grow well and actually ripen in their particular geographic region. I have drafted a proposed Wiki page that I hope to soon submit for approval by wiki links. Of course there is no guarantee it will gain approval for publishing, but if it does it would give those forum members who have first hand experience with particular varieties to share their data with other forum members who could then benefit from the data provided. For example: If I see data from a member who resides in a climate similar to mine who is reporting success in ripening, then I could use the degree day calculator to compare his climate to my local here in Kent, wa. If the degree days are close enough, then I could make an informed decision, rather than trusting a nursery’s recommendation.
So below is my proposed draft and I invite your suggestions for improvement. I hope to submit it soon for approval so that forum members can input data starting this fall of 2021.
Thanks for your constructive input:
Rough Draft Wiki page
On the forum titled Growingfruit.org, members share their fruit growing experience freely with other members. The topics vary widely and cover almost every fruit or plant life that one can imagine. A member desiring to learn about a new plant variety or who has questions can seek the advice of more experienced growers by posing the question and obtaining advice and suggestions from other more experienced members who often have personal experience relevant to the inquiry. This website services members worldwide giving members access to a wealth of knowledge and a treasure trove of expertise in grafting, propagation and production of fruits and vegetables.
I am proposing a wiki page that forum members can access to add their specific firsthand knowledge and data about a specific topic: “The Climatic Requirements for growing and ripening Persimmons”. The reason I would like to create such a wiki page is that there is a need for members wishing to successfully grow a given persimmon cultivar to obtain reliable data from others who have experienced success and are willing to provide data to others who may be considering growing the cultivar.
Like most other fruit trees, Persimmons require several years once planted to actually go into production. The majority of fruits can be grown with little regard for the climate, as long as the growing zone is respected and eventually obtain ripened fruit, not so for persimmons! If the climate zone and growing conditions for persimmons do not provide 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. So you could have a perfectly growing tree that never produces useful fruit! There are other types of fruits such as figs that need extended heat days to ripen. While this proposal focuses on the Persimmon, once it is understood, it could readily be adopted or modified to evaluate other types of fruit.
While plant Nurseries do provide some advice on suggested growth zone, they do not have the specific information to determine if any particular cultivar of Persimmon will do anything other than grow. Moreover, in spite of numerous articles on persimmon growing on the web, not one provides a calendar reference or zone map that is oriented to ripening potential for each cultivar.
There are a number of local forum members in my region near Seattle who would like to find an efficient method to determine which varieties of Persimmons will actually ripen in our somewhat short cool, maritime climate. Many have varieties that do not fully ripen, or never get fully ripened to be worth growing! I even know one lady north of me who constructed a canopy over her persimmon trees to provide the microclimate for her trees. A considerable investment in time and resource. 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 also pin down the climate by zip code so that one can make an efficient and accurate comparison to determine ripening potential for another location. The same is true for Asian varieties.
It would very productive if one could determine in advance which cultivars have a chance of ripening in a particular location, before selecting that cultivar to grow or graft over an unsuccessful existing variety.
So I am proposing a Wiki page where forum members who have and are willing to provide reliable data on any particular cultivar of persimmon (Asian, Native, or Hybrid) can access to contribute useful data to share with other forum members.
The page would be a simple fixed spreadsheet for entering the following information.
Source: This would be the members forum user name. For example my growing fruit.org user name is @Dennisd. Other forum members can use this information to contact the source to ask any particular questions.
City: Large City near the Source of data.
Zip code: Enter the zip code of Source.
Persimmon cultivar name: This would be the specific name of the cultivar for which the data applies.
Astringent vs. non-astringent: Enter type
Rootstock: Enter the rootstock name (D. Virginiana, D. Kaki, D. Lotus)
Age of Tree: Enter the Years the tree has grown if known, or 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 fruits were ready to harvest.
Condition of fruit harvested: Describe whether the fruit could be consumed immediately after picking, if it required additional time and procedures to fully ripen before consumption or any special treatment to overcome astringency.
Finally, if possible, it would be desirable to safeguard a member’ s data if editing the data could only be done by the Source of the data.
With the above key data it would be feasible to determine if the particular cultivar reported may be suitable to grow in another geographic location by comparing weather data and average daily temperatures to any other potential location. This comparison can be accomplished by comparing the cumulative 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). 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 F.
(Note: I would suggest this base temperature for Persimmon since most experienced grafters use 70 F as the minimum sustainable temperatures to begin outdoor grafting. ) Using this base in the formula on the following website you can generate the degrees days that were actually required from the current year for ripening to occur. The sum of this data “Da” (actual data) can then be compared to “Dd” ( data at the desired location) to obtain a statistical assessment of potential success. This comparison should be based data generated within the same timeframe for the actual reported and the desired growing sites. I chose the below website for its ease of use, simplicity and its applicability anywhere within the US. When using this website to estimate growing degree days, you need to use the “Cooling” button rather than heating to capture the actual heating data above the base temperature.
Kent, Wa 98030