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Dangerous circling tree roots, tomatoes ripening off vine, storing seeds

Gardening columnist Don Kinzler takes questions from readers this week about circling roots, ripening tomatoes and storing seeds.

circling roots October 2022.jpg
During planting, if roots are left in a circle as they come out of the pot, the roots continue to grow in that position. The trunk continues to expand, and the circling roots continue to expand, until they meet. The circling roots are called "stem girdling roots" and are unfortunately a common cause of death or decline among trees.
Contributed / Don Kinzler
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Q: I have a Cathedral elm and a maple that both have roots wrapping around the trunk where they go into the ground. Both were planted by a professional. How bad is this, and what happens if I cut these roots? – Elizabeth P.

A: The circling roots are called "stem girdling roots" and are unfortunately a common cause of death or decline among trees. Because these roots are sometimes invisible and just below soil surface, the problem often goes undiagnosed as trees mysteriously decline.

The symptoms of decline caused by stem girdling roots often don't show up until 10 or 15 years after trees are planted. During planting, if roots are left in a circle as they come out of the pot, the roots continue to grow in that position. The trunk continues to expand, and the circling roots continue to expand, until they meet.

The circling roots begin to choke the tree trunk like a boa constrictor. The trunk tries to expand around the circling roots but becomes "girdled" and water and nutrients can no longer move up and down within the tree.

The only hope for remedy is to detect this issue before the tree begins to decline and cut the circling roots away. Naturally this is easier when trees are younger, and before roots become large. If left untreated, trees will likely die.

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There’s a possibility that removing the circling roots will shock the tree, and removing roots of established trees is usually not recommended. But if left intact, stem-girdling roots will eventually kill the tree, so any risk of shock is a risk worth taking, in this case.

In defense of the tree planter, many past recommendations were to leave tree roots undisturbed when trees were removed from pots, because disruption could cause transplant shock. We now realize the importance of untangling or cutting circling roots when planting.

Q: Some of my friends swear that all green tomatoes will ripen off the vine at the end of the season, if picked and taken indoors if you just wait long enough. My understanding is that the tomatoes need to be at a certain point before that will work. So the question is, will all the green tomatoes remaining on the vine eventually ripen indoors? – Charlene N.

A: No, all green tomatoes remaining on the vine at frost time will not ripen if brought indoors. Immature fruit won’t ripen, only those that have reached the proper degree of maturity.

From Purdue University: “If frost comes early, keep in mind that tomatoes that have reached at least the mature green stage, can be ripened off the vine. Look for a color change to at least a lighter green, and a little bit of blush is even better. The tomatoes that are still immature green will never ripen, so save those for the compost pile.”

Tomatoes that have reached the mature green stage ripen best at about 70 degrees F. indoors. Place the fruits in single layers and cover with newspaper or brown paper bags, which traps ethylene, the gas that aids in ripening.

Q: I harvest seeds of zinnia, cosmos and marigold each fall to plant the following spring. I usually store them in my basement over the winter, but I’m wondering if my unheated garage might be a better option. – Mary R.

A: The ideal temperature for storing seeds, once they’ve thoroughly dried, is between 32 and 42 degrees F., making the refrigerator an ideal place. Garages tend to fluctuate in temperature, and the ideal temperature range is more difficult to maintain consistently. If you have room in the refrigerator, the consistency of temperature would be better.

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Seeds are best stored in tightly sealed glass containers. Different kinds of seeds, each in individual envelopes, can be stored together in the same large container.

A small amount of silica gel desiccant can be added to containers to absorb moisture. Craft stores sell silica gel for drying flowers, or you can reuse the small packets that commonly come with some shipped items.

More gardening columns from Don Kinzler

If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at donald.kinzler@ndsu.edu . Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at donald.kinzler@ndsu.edu.
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