In one North Dakota nursery, Siberian peashrub is seeded during the last week in July or the first week in August. A cover crop of oats is seeded between the tree rows early enough to give winter protection. Harvesting In the US, the optimum time for collecting seed is less than two weeks, usually in July or August. Since seeds are ready to collect as soon as the fruit ripens, the pods should be gathered by hand as soon as they open. For vegetable trials, greener pods should of course be harvested.
Good crops occur nearly every year.
Nitrogen-fixing rhizobia were reported in the species before 1900. Host infective patterns were quite uniform but some nonreciprocal cross-inoculation was observed. Caragana rhizobia reisolated from nodules they formed on Trifolium pratense retained the ability to nodulate Caragana. Throughout the life of a Caragana nodule, the volume of tissue functionally active in N-fixation remains more or less constant. As the nodule becomes larger, the ratio of the N-fixing volume to total nodule mass becomes smaller.