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Ron Smith answers reader's questions about the world of plants and gardens.


By Ron Smith, Horticulturist

NDSU Extension Service

Q: We planted several arborvitaes along our fence last April. They have looked nice and green all summer. We have noticed that the plants are turning brown on the inside, but the tips are still green. Is this normal during fall? I live in Michigan and the nights have been getting cooler, sometimes in the low 40s. We thought maybe we should give them more water because we had been watering the plants a couple of times a week. (e-mail reference)

A: Interior needle cast is normal for this time of year, so probably this is nothing to worry about. Don't change your watering habits unless you are keeping the soil too wet. Do a hand check before watering. If the soil is moist, don't water.

Q: I have a keepsake azalea that blooms and then looks like it is dead. Do they go dormant? Should I keep watering it? I keep it in the house throughout the year. (e-mail reference)

A: It has to produce foliage sometime or else it wouldn't have the energy to flower. Yes, dormancy is normal, but leafing out also is needed, so the leaves must have been there at some time prior to flowering. Azaleas that are used as indoor plants often are meant to be throw-away plants after they flower. If this one doesn't show leaves in about six weeks, then this probably is that type of plant and should be dumped.

Q: I inherited a corn plant after it outgrew my mother’s house. It is tall, but has a very thin stalk. It only has leaves on the top 3 inches. Can I cut the top off to encourage new growth lower on the plant or would that idea be a death sentence? (e-mail reference)

A: The better option would be to cut the plant back to a stub about 4 to 6 inches long. Take the rest of the cane and cut into 4-inch sections, with the top end of the cut square across and the lower cut being at an angle to make the distinction between the top and bottom of the plant. Allow the cuttings to cure for a day in the air. Make a flat of moist peat moss. Lay the cuttings in the peat on their sides, but barely covering them. Keep the peat and cuttings moist through daily syringing. In about six to nine weeks, growth should be apparent at the tops. Also at that time, the roots should be visible, starting at the slanted end. Give the plants a couple of more weeks of growth. When the roots are about 3 to 4 inches long, gently lift the cuttings out and pot them in a high-organic, pasteurized potting soil. Lightly drape a clear plastic bag over the leaves, which will be growing at an off-angle from the perpendicular, to maintain high humidity around the fresh cuttings and continue for at least a couple of weeks. In the meantime, the mother plant also should have sprouted new growth if you kept the soil moistened during the interim.

Q: We have a lot of boxelder and wild cherry trees. I heat my house and body shop with an outside wood boiler. Are the boxelder trees any use other than taking up space? The wood does not produce a lot of heat. My plan is to remove the boxelder trees to give my cherry trees a place to expand. (e-mail reference)

A: Some folks collect the sap in early spring to make a boxelder maple syrup. Anyway, go for burning the boxelder trees. The cherry trees will appreciate the extra room.

Q: I have a variegated spider plant. I clipped off the plant from the parent plant last year. I repotted the plant in a plastic pot. I grew it in a south window and then brought it to work. It grew well for a long time sitting on top of my monitor. It’s still sending out plenty of leaves, but I'm noticing that many of them are folding down the center and not as bright colored. Is this a sign of anything? Also, my desk is not near a window, but is under florescent light for 12 to 16 hours a day, not counting weekends. It doesn't seem to bother it that much, but should I be worried? Also, is there anything I can put on my houseplants that will keep cats from eating them? I noticed that the cats pick on the ones with the long, thin leaves the most. I'd like to discourage them from eating on the plants, but don't know how. I've hung a number of my plants, but some of them are getting so big and heavy. (e-mail reference)

A: This probably is a good sign that your office lights need to be replaced. If it has been more than a year, see if you can talk the custodian into getting some new lights installed. These are good low-light plants, but do much better if their maintenance lighting can be kept up to par. Houseplants actually "read" light quality better than our eyes do. Also, with three cats in our house, we have to keep the plants out of their reach. When we bring our plants down to water in a sink or bathtub, the cats are quick to notice and attack. About all we do is scold and/or spritz the cats with vinegar water. That at least stops them from doing it for a period of time. However, other than that, I don't know of anything else that will keep cats away from plants.

Q: I was looking on the Internet about how to fertilize jade plants when I ran into your Web site, but didn’t find the answer I was looking for. I've had a jade plant for a few years. At the same time, I have attempted to be more earth-friendly by composting. I've never used compost before and don't really know the process. Do I put the compost on top of my plants in place of fertilizer or is it not a good idea to use compost on houseplants? On a side note, I noticed a question someone had sent you about a jade plant’s ties to prosperity. It reminded me of something that happened to me several years ago. I got clean from drugs at that time, so someone gave me a jade plant as a gift. One night I relapsed and the very next day my beautiful plant was dead. I think I left a window open and the cold got to it. I've been drug-free for several years and my new jade plant is doing terrific. (e-mail reference)

A: Thank you for sharing the good news! Compost can be used with most houseplants by using as topdressing over the soil in the pot or as a component. Use a 25 percent to 30 percent potting soil mixture. The nutrients slowly become available to the plant, which mimics its natural setting.

Q: My father-in-law gave me some iris plants, but more than I can use. My sister wants some, but lives in another state. Can I mail them to her? Is there something I need to do to the plants so they survive? Also, can I store them through the winter? I'm new at this. (e-mail reference)

A: Mail them now. Wrap the plants dry in newspaper and with the foliage cut halfway back. For now, get them planted as soon as possible, unless she lives in Alaska.

Q: I obtained a kitten that took to liking my fiscus tree a little too much. The cat would try to climb the tree when I wasn't around. The cat tore some limbs off and scratched the bark when it fell onto the ground. I thought about killing the kitten, but decided against that idea. I took the fiscus and replanted it after watering down the roots and placing it in a larger pot. I also added Miracle-Gro. Any help you could provide would be great! (e-mail reference)

A: I'm glad your thoughts only progressed to that of thinking about killing the cat. I suggest getting the front claws removed if the kitten is going to be an indoor cat because it will be much easier on the furniture and your ficus. You did the right thing for the plant. With time, the wounds from the kitten should heal. If the natural light situation is significantly different (it doesn't take much for it to be so), you might want to bring a plant light into play. Put the light on a 12-hour timer. Even if you do lose some leaves, the plant will stabilize under the new light and location. I have lived with cats all my life. While kittens are mischievous and annoying with their attacks on things unexpected, they eventually do mature and make good lap companions later in life. They love you no matter how old or ugly one might get as long as you give them a lap and a little attention.

Q: I'm writing you because of my problem with a dieffenbachia plant. I’m not sure when I should replant the dieffenbachia to a bigger pot. Where should I cut back the leaves? The plant seems to be doing well, but some of the tips of the leaves are dying and getting brown. Please help. (e-mail reference)

A: Most likely those are the older leaves showing the symptoms you describe. If so, cut the leaves off back to the stem. If you can, knock the plant out of the pot and see if the roots are encircled. If so, it’s time for repotting into a larger pot using a standard pasteurized potting soil.

Q: I am from Williston and hear you every time you are on the radio. I’ve especially enjoyed your discussions about wine making and tasting. I have a pasture that has a creek through it. Along the creek are a lot of trees, including quite a few boxelders and some that are dead or dying. I have noticed a certain type of growth many times, but more so this year. I have referred to it as angel hair or bridal veil. I thought of it as some form of saprophyte. I have tried to find a scientific name and a published picture, but have not found anything on the Internet so far. (e-mail reference)

A: Thanks for being a loyal listener to the “Hear It Now Program” on Prairie Public Radio. Thanks also for the excellent photos, which made it easy to identify. It appears to be wild clematis of some kind. What you are seeing are the seed heads of the plant where the flowers used to be. This is a guess, but I'm fairly certain that is what you are looking at. It is an old vine that has attached itself to an old tree and puts on this show every year at this time.

Q: I have a hearty Concord grape plant that I grew from a root at my mom's house. She had her vines for about 30 years. She gave each of us a piece of root and told us to plant it. My brothers and sisters did this in late summer or early fall, but they never got a grape plant to grow. Mine ended up in a dark garbage bag and placed inside a rolled up carpet in the garage (not intentional). We didn't find it until spring, so we planted it. Ours is the only one that survived. My daughters-in-law would like to grow some in their yard. How would we go about doing this and at what time of year? Do I need to chop off a piece of the root (scares me) or use a branch cutting? (Scandia, Minn.)

A: Either tactic will work, but usually the stem cuttings work best. Wait until the vine drops all its leaves and then make some cuttings that are about 12 to18 inches in length and wrap them in damp sphagnum moss. The cuttings should be refrigerated until next spring. At that time, stick the cuttings in a pot using sterile or pasteurized soil for rooting. Keep the media moist, but not soggy. In a few weeks, roots should form, which can be planted. Another approach is to take the long vines and pin them into loosened soil around the parent plant. Various methods of propagation can be found at

Q: I live within 100 yards of the Red River. I have a few bur oaks in my yard. The biggest measures exactly 10 feet in circumference at about 3 1/2 feet above the ground. Do you have any estimate how old this tree is? How many more years do you think a tree of this size will live? (Moorhead, Minn.)

A: That is one large oak! My guess would be the tree is 100 or more years old. Its age could be determined by a boring taken from the trunk at about 4 feet up and then counting the rings. As to how much longer it will live depends of the overall health of the tree .If there is internal rot, it could topple during the next windstorm. If it is physically sound, it could be around for decades.

NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161,
Editor:Rich Mattern, (701) 231-6136,
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