Plum trees are generally productive for around two decades, which I think is fair considering the quantity and quality of the fruit. After 20 years in the ground, plum trees not only stop or nearly stop producing, but their bark may begin to crack, the result of borer infestation or bacterial canker disease. The cracked bark is an open invitation to termites, which have a penchant for taking up residence in dying plum trees.
Santa Rosa is the only Japanese plum (Prunus salicina ‘Santa Rosa’) that is self-fertile, which means that it does not require another plum tree to produce fruit. However, you can increase your crop by planting a Satsuma, Burbank or Shiro variety in the vicinity. Japanese plums, which are purplish-red in color, are generally sweeter than European plums (Prunus domestica) such as Damson and Green Gage, which are navy blue and yellow-green, respectively. All European plums, however, are self-fruitful.
The only problem with plum trees is that their entire crop ripens over a two- to three-week period. You must be prepared for the harvest avalanche and it is wise to place a tarp under your tree to catch falling fruit. One strategy for maximizing utilization of your myriad plums is to place the fruit in zippered storage bags and freeze them. They should keep well in the freezer for many months. You can also make the plums into jam that will last a long, long time. And then — if you are lucky to have a wife like mine who loves to bake — create a plum crumb dessert or two for the family to enjoy.
A Santa Rosa plum tree is perfect for a small sunny yard since its mature height is around 20 feet. Prune it lightly since fruit is produced on spurs or small stems that grow between ¼-inch to 1 inch per year. By close observation of the fruiting habits of a plum or any other deciduous fruit tree, you will learn where and how much to prune soon enough.
My Santa Rosa plum trees have a tendency towards alternate bearing. This means that you have a heavy crop one year and a light crop the next. Alternate bearing is observed most notably in apple, pear, pecan, pistachio, tangerine (also known as Mandarin orange) and avocado. Avocado prices in the supermarket have been known to fluctuate from one year to the next due to avocado trees’ extreme on-again-off-again production cycle. In truth, nearly all fruit trees, as they age, become increasingly prone to alternate bearing.
Speaking of homegrown fruit, I received an email from Anne Marie Darrach, who lives in Valencia. She writes: “Some time ago I wrote in and asked about growing cane berries (blackberries, raspberries, boysenberries) in our hot Southern California climate. Here is what I discovered. The Arapaho blackberry was a complete disappointment. After almost three years in the ground, I did not receive one berry. The Heritage raspberry is growing back for the second year, but is only 6 inches tall now. The possibility of eating any raspberries does not look promising.
“The winner is: thornless boysenberry. It produced fruit the first year and this being its second year, has given us 50 berries. When the berries are allowed to turn deep purple they are very tasty. This plant was grown in a location with a few hours of midday sun, against a brick wall. I highly recommend this plant if you can find it. Mine came from the Lowe’s store, but for some reason Lowe’s did not carry this plant this spring. If you want to grow cane berries, the boysenberry is the one to grow. And, yes, they are thornless for the most part.
“I was so happy with the crop of apples from our Dorsett Golden tree this year. There is an Anna variety close by which is not as large as the Golden, and also has a fair amount of apples, too.
“I have lost track of how many apples we picked, but I estimate it must have been 100. We didn’t apply much fertilizer at all because we have two dogs that would eat any trace of plant food they could sniff.
“What great trees. The apples are tasty and crisp; I rarely see any insect damage and I did not use any pesticide at all. All it takes is five years in the ground to let the trees become established.”