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Don Kinzler, Published December 17 2010

Hortiscope: Rings can help you guess tree’s age

Q: This fall, I had three somewhat decrepit ash trees cut down. A friend with a chainsaw cut a cross section so I could count the rings. How far out do the countable rings go? Do I count the rings in the cambium layer and/or the bark?

We bought the lots with the trees growing on them in 1950. I count 69 rings if I only count the rings in the woody core. Some rings are much larger than others.

I suppose I could match that up to our annual rainfall if I had the time, patience and statistics to do it. I’m not sure where I’d find annual rainfall records. (Cooperstown, N.D.)

A: Annual growth rings are difficult to count accurately but will give you a good approximation about the age of your trees. Growth rings are influenced a great deal by rainfall intensity and duration. We could have a very wet spring, which would result in a generous ring. However, a dry summer followed by a wet late summer or fall would give you another ring to be counted.

For data on precipitation, I’d suggest contacting Adnan Akyuz, who is the state climatologist. He is very sharp and full of useful information that we in horticulture and forestry find quite helpful.

Q: I am looking for vermiculite for the square foot garden I plan to start next spring. I found vermiculite in the home insulation section of a store but nothing in the garden section. Will vermiculite used for home insulation also work for gardening? (e-mail reference)

A: I don’t recommend the use of vermiculite for various reasons. It is too light in weight to provide a stable anchoring media for plant roots. Unless you can find certified asbestos-free vermiculite, you shouldn’t use it because of the obvious threat to respiratory health. Even if you do find certified vermiculite, there is mica dust that is generated from pouring it out of the bag. While a onetime exposure will not kill you, it should be avoided whenever possible.

My wife and I have found that a good combination of sand, soil and generous amounts of sphagnum peat moss will deliver just as good of a garden crop.

Q: I planted a hybrid poplar in my yard about two or three years ago. This year, it spawned three suckers. I cut the tree down and started to dig out the stump.

If I cut the roots about a foot from the stump, will that kill the roots, or do I also need to apply herbicide? Someone told me the tree might be a dreaded Lombardy. If so, is Trimec the answer? (e-mail reference)

A: You probably will need to apply Trimec to the sucker growth that is likely to take place next spring even if the tree isn’t a Lombardy.

Q: I have a goldfish plant that I received at my grandmother’s funeral. It is ready to be repotted, but I am unsure if it needs to be in a hanging or standing pot. During the summer, I have the space for it to hang, but it’s hard to keep it out of the cold without having a standing pot during our Michigan winters. (e-mail reference)

A: As you will soon find out, this is a plant species that needs pampering.

Goldfish plants need frequent misting, but the soil should be kept on the slightly dry side during the long winter months. The night temperature should be 65 or lower, which is lower than we humans like it to be.

It makes no difference to the plant if it is in a hanging or standing pot. The trailing stems and flowers drape over the furniture or stand it is placed in.

Since you live in Michigan, you might want to supplement the light with a plant grow light for 12 or more hours a day.

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 ronald.smith@ndsu.edu.