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Hortiscope: Reader wonders how to sterilize a black walnut tree

Q: I enjoy reading your seemingly infinite insights on trees. I have come to realize how much people care for their black walnut trees. I also am fond of the two I have in my backyard. However, I would love to have one that doesn't produce nuts. I'm talking huge crops every year! Has anyone ever figured out how to sterilize a black walnut tree?

A: Not to my knowledge! The tree contains male and female flowers. I think this makes it rather difficult to come up with a way to eliminate the messy nuts that these trees are large producers of. If the flowers were perfect (hermaphroditic), with both sexes present in one flower, such as an apple tree, then fruit reduction or elimination would be a good possibility.

Q: I've just moved into a house that has three jade plants growing in a sunny garden. Two plants were flowering when we moved in, but now the blooms have faded. Should I deadhead the clusters of brown, crispy flowers? Should I pinch them off or use garden shears? Is now a good time to fertilize the plants?

A: I would suggest using sharp pinking shears to nip off the spent flowers. When the plants start to exhibit new growth, you can give them a little fertilizer. Use a liquid or granular fertilizer that you will lightly spread under the canopy of the plants. For those readers in northern climes, bring the plants indoors for winter.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail