Plums (Prunus spp.) come in an amazing variety of colors, textures and flavors, with blue, purple, red and yellow varieties. However, the standard of excellence for plum flavor is the "Green Gage" plum (Prunus domestica italica), one of the only plum varieties that is green when ripe. They grow in U.S. Department of Agriculture plant hardiness zones 5 through 7 and resemble the small, wild plums that children love to pick, but pack a sweet, delicate flavor that is unsurpassed.
The "Green Gage" plum originated in 17th-century France and is also known as the Reine Claude plum. This type of plum has numerous cultivars, and they are widely regarded as having the most perfect plum flavor. One common complaint children have about plums is their sourness, a result of natural acidity in some varieties. The color of "Green Gage" plums may convey sourness, but they are sugary sweet -- your kids are sure to adore them. For the cook in the family, they provide the best possible culinary qualities of any plum and are renowned by chefs worldwide.
If you have a delicious green plum growing at your house and you think it may be a "Green Gage," there are a few notable characteristics that can help confirm its identity: Its skin is russeted, meaning it has brown specks or streaks when fully ripe. This doesn't make it the most visually appealing plum, and for this reason it's easily mistaken for wild varieties. Like wild plums, "Green Gage" is very small, sometimes growing to only an inch in diameter. Finally, its flesh may have either a green or yellow hue.
"Green Gage" ripens very late in the season compared to other varieties, sometimes well into the month of September. Flowering is also later in spring than most other plums. "Green Gage" can also self-pollinate. If there is a single green plum tree, it is likely a "Green Gage" because the other green plums require the pollen of a second tree to make fruit. One final characteristic that distinguishes the "Green Gage" plum is the tendency to bear extremely heavy crops one year, followed by little to no fruit the next year.
Other Green Varieties
There are other varieties of plum that are ripe when green. Strangely, these plums become highly colored when fully mature, but have the best flavor when they are still green. Most of them have been bred for their adaptability to the climate of the southeastern states and are less common in other part of the country. These include "Bruce" (Prunus "Bruce"), hardy in USDA zones 6 to 8; "Segundo" (Prunus "Segundo"), hardy in zones 5 to 8; and "Robusto" (Prunus "Robusto") hardy in zones 7 to 10. These all require cross-pollination from a second variety and ripen in late spring or early summer.