Yellow Ussuri Plum Seeds

This extremely hardy yellow sweet plum has been known to withstand temperatures of -40 F or more. From Northern China, this is one of the species used to create 'Shiro' and other plums that are incredibly sweet and delicious. Not much is known about the origins of my original stock plants but thanks to a customer who let me grow out several thousand seedlings of one plant he had in his orchard, I was able to select several black knot resistant plants that produced amazing yields of sweet yellow plums. New generations have provided me a sort of feed back loop that immunity is nearly impossible but one tree in particular is the shining star of this large grow out of over 5000 seedlings that shows only minor amounts of this disease. This tree is now over 30 years old and going strong.  

As a species plum, it is one of the few truly tree type plums growing to 40 ft. or more with a strong trunk and wide branching angles. The plants also produce no suckers. The flowering occurs in early spring and despite late frosts often sets fruit within a narrow time frame making the plant flower and set fruit missing frosts. The main parent tree I use is in a frost pocket and despite its location it always has a crop. Many types of pollinators are very active on the flowers as few trees are flowering at this time in spring with low daytime temperatures common. 

Of all the tree crops, I have experimented with this one took a long time to overcome the disease barrier of black knot. You just can't prune it off and hope it goes away.  It is interesting in that black knot adapts to trees that appear to be resistant for some time.  In an ironic genetic twist of fate, the trees with only slight black knot disease also are the most productive so the disease must play a role to some extent in the plants success of reproduction. Over time my population stabilized and the yellow fruit persisted. There is very little variation in seed grown plants of this species. I am currently using the original parent tree for seed only. This selection has not discernable black knot strikes on it. The image posted shows the size of the trunk as well as the height and growth habit. 

Ripening begins in early August and continues through early September. Scionwood is available upon request of the "Ecos" selection of this parent tree with an order of seeds.

To germinate the seeds, plant outdoors in the fall 1/2 inch deep in a garden type soil with good water drainage. Seeds will almost all germinate in one season (one dormancy) although a few seeds may sprout in the second year.

To do the indoor method, store your seeds in the refrigerator from 33-38 F for 60-120 days in a ziplock bag with lightly damp Canadian peat moss. Seeds will germinate in roughly 60 days as the seeds will start to crack open slowly.  This is the time to pluck them out and plant them in a pot. Make sure the soil mix is light and well drained. Ussuri plum seeds rot easily in high organic soils. Some seeds will need an additional warm and cold period to sprout if some do not sprout the first year. Plants can grow to 3 ft. in one year from seed. Very vigorous from seed.

Plants can produce fruit in 3-5 years from seedling. Flowering begins when the tree reaches 6-8 ft. tall. Heavy fruiting begins when the caliper of the tree is within 2-3 inches.