Thank you for your question.
Generally speaking, fruit will have the most flavor if it is allowed
to ripen on the tree and eaten right away. But, it will store longer
if it is picked before it is fully ripe.
"As color develops there is usually a softening of the flesh. With
experience with a particular variety, one can soon correlate color
with taste and judge when the fruit should be harvested from the tree.
Ideal storage conditions for plums consist of maintaining a
temperature of 31 to 32 degrees F and a 90 to 95 percent relative
humidity. Under such conditions, storage life of plums is from two to
four weeks. For many, the home refrigerator will be the best method of
preserving the after-harvest life of the fruit until it is consumed or
To store, keep at room temperature until ripe. Refrigerate ripe fruit
to preserve sweetness and quality.
Gardening in Western Washington
When to Pick Tree Fruit - PLUMS & PRUNES
"With both Japanese and European varieties of plums, the taste test is
probably the best way to determine readiness for harvest. They should
just be beginning to soften. The taste test should reveal fruit which
are soft, sweet and juicy.
Watching ground color on many European varieties is often a help. It
becomes yellowish in contrast to the dull greenish color of the
immature state. Ripeness of Italian prunes should be determined by the
"In order to obtain the highest quality fruit, apples, apricots,
pears, and plums must be harvested at the proper stage of maturity.
Once harvested, proper storage is necessary to maximize storage life.
Plums. As plums approach maturity, the fruit develop their
characteristic color. The fruit of blue or purple varieties
('Stanley,' 'Damson,' and 'Mount Royal') change from green to
greenish-blue, then to dark blue or purple. The ripened fruit color of
other varieties vary from yellow to red. Color, however, should not be
the sole basis for harvesting plums. As they ripen, plums begin to
soften, especially at the tip end. They also develop their
Harvest and handle plums carefully. The fruit can be stored for
approximately 2 to 4 weeks at temperatures near 32°F."
How to Harvest and Store Plums
1. Pick plums when they come off the branch with a slight twist.
2. Remove red plums from the tree when they're fully ripe and tender.
3. Harvest other types when they're still firm if you want to;
they'll ripen off the tree.
4. Refrigerate ripe plums for up to three days.
5. Ripen hard plums by placing several in a loosely closed paper bag
and leaving them at room temperature for a day or two.