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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: We are building a new home, so the electric company trenched a hole for the electric lines a few feet away from my ash tree. The tree isn't quite as high as the house (single story), but almost. Do you think this will kill the tree? Is there anything I can do to keep from losing it? (e-mail reference)

A: While not good for the tree, this action usually does not harm the tree to any degree. The hope is there will be some root regeneration from the cutting if the tree is otherwise healthy and vigorous. There isn't much you can do in this case. Ash trees are fairly tolerant of this kind of abuse. Depending on where you live, your bigger worry is the emerald ash borer.

Q: I brought a geranium in the house for the winter. During March and April, I had five beautiful, full, pink blossoms. However, the stem was quite slim, so the blossoms drooped from the weight. The plant also is acting almost like a vine because it is spreading out differently this year. It looks very healthy, but flimsy in the stem department. I feed it about every two weeks with Miracle-Gro during the winter. Have I done anything wrong? Do I cut it back so it will become sturdier? Do you have other suggestions? The pot now looks like it may be too small because of the way it’s spreading out. Is there such a thing as a geranium vine? (northwestern Minnesota)

A: You were too good to it during the winter. It became "flabby" from the excess fertilizer and didn’t get enough strong sunlight. Cut it back and set it out on the warmer days. Bring it back in if a frost threatens. Plant it outdoors after the Memorial Day weekend and it should be fine.

Q: What can I do if my very large tomato plants are fruiting already? I had my plants in small cups. I planted them two weeks ago. Can you please give me some ideas? (e-mail reference)

A: Pick the fruits off and throw them away. Then give it some Miracle-Gro. Make sure your tomato plants get ample water and plenty of direct sunlight. Repeat the fertilizer application in about three weeks.

Q: I would like to plant a permanent snow fence. It is in a rural setting with a couple of miles of open space to the northwest. The west fence line is approximately 75 feet from the edge of my driveway. I am considering maybe cotoneaster and cedar. Horses pasture in that area, but I would plan to put an electric fence there. Thank you. (Brookings County, S.D.)

A: Both plantings would work. However, I’m assuming you mean the arborvitae or juniper when you refer to cedar.

Q: I would like to plant a privacy hedge, so I have looked at cotoneasters, ninebark and lilacs. I have a small backyard. What can I expect for a growth rate per year? I understand the cotoneaster will require a lot more pruning and maintenance. What would you recommend? (West Fargo, N.D.)

A: Why not ignore all of those and consider something immensely better, such as the Arnold red honeysuckle? Go to to see photos and get some information on this beautiful shrub. It is underused in our landscapes.

Q: I’m going to plant San Marzano tomatoes in pots on my south-facing deck. Since these have 80 days to maturity, is there anything I can do to get a good yield? Are night temperatures a factor? I'm looking forward to making spaghetti sauce from them. I enjoy your column and look forward to your advice. Thanks. (Grand Forks, N.D.)

A: The location is perfect! Just try to keep the moisture level as consistent as possible and don't overfertilize. Wide swings in fertilizing or watering can mess up a good production schedule. Your spaghetti sauce sounds fantastic! Spaghetti with a good glass of red wine is one of my favorite comfort foods! Thanks for the nice compliment about the column!

Q: I have a flowering crab apple tree. My neighbor noticed a large, hairy larva sack on one of the branches. I cut off the branch and got rid of the sack. Any idea what it was? I was very hasty in throwing it away. I should have taken a closer look. (e-mail reference)

A: That probably was a collection of tent caterpillars that are voracious foliage feeders. You did the right "organic" thing by doing what you did and likely got them all. Check the tree in the next couple of days to make sure there are no stragglers still feeding.

Q: I was reading some of your material on the Web, so I’m wondering if you could answer a question. When is the best time to prune my techny arborvitae and how much I can prune off? I have two that are doing well (one is thicker than the other because it is in more fertile soil and gets more sun). They are 7 to 10 years old. I’ve never pruned them, but would like them to stay the height they are and be a little skinnier. The green portion of the branch does not go that far into the tree, so I am afraid to cut into that. (Forest Lake, Minn.)

A: You can prune anytime before new growth emerges. Now would be ideal for our part of the country. Do not go beyond any green leaves because the bare spot will remain and not fill in.

Q: We have a 4-year-old Bartlett pear tree. Last year, it blossomed and had a few pears on it, but this year it had no blossoms. Any ideas? (West Yarmouth, Md.)

A: Your area of the country probably experienced lethal temperatures this past winter for the flower buds. Let’s hope this was a rare occurrence so you can enjoy the blossoms next year.

Q: I am concerned about an autumn maple that is located in my front yard. The tree was planted seven years ago when our landscaping was installed. I've been concerned about this tree for several years, so last winter I pruned the tree, hoping that it would help it. I also use fertilizer spikes in the spring. I believe the tree gets too much runoff water from the front of my house, even though it is planted on a sloped grade. Our soil has a lot of heavy clay. It’s likely that good soil wasn't put in the hole and the hole for the tree wasn't dug large enough when it was planted by the landscaper. Most of the branches on the east side of the tree have died off, so they have been removed. I took a few photos of the leaves for you to review. The leaves look wilted to me, but don't seem to be diseased. What is your opinion? (Lafayette, Ind.)

A: Your tree looks just fine. What you are seeing is the natural droop of a black maple, which is very similar to the sugar maple characteristic. It could be a black maple species or an autumn blaze with some of the genetic material of the black maple mixed in, which is not a bad thing. Since you sent me the photos, I would suggest you have that lower branch removed before too much longer. It always will be at that height and will grow to be more of a problem with age as far as mowing around the tree. I also would suggest forgetting about the fertilizer stakes because you are wasting your money and time. Your tree will be fertilized incidentally when you fertilize your lawn.

Q: I've read just about everything that there is to read on the Web about gardenias. I love my two little plants, so I would very much like to rescue them! I noticed that my leaves were drooping and weak. I watered them and tried watering them again, but nothing happened. During a closer study of my plants, I discovered they had spider mites. I gave the plants a bath and repotted. The plants seem to have perked up, at least for now. Can spider mites cause a plant to droop like that or was it a lack of humidity that made me lucky enough to find the little buggers? What's my next step if I want to keep these plants alive? I'd hate to lose a bet as to whether or not I can grow them inside. (e-mail reference)

A: The low humidity set the stage for the spider mite invasion. The mite’s proliferation and feeding habits caused the plants to wilt. Washing the plants destroyed most, if not all, of the current generation of spider mites. You never should bet anyone when it comes to growing gardenias. They are enough of a challenge for professional growers, even with all the technology, history and right conditions at their disposal. They need shade, acidic soil, southeastern Georgia-type humidity and continuous moisture, but not soggy, to thrive.

Q: I finally have some tulips that bloomed this year. For years, I couldn't get them to bloom, so I improved the soil and added humus and peat moss for better drainage. Earlier this spring, I fed them some bulb fertilizer. Once they bloom, should I water them the same as I do my other perennials? Should I fertilize them this fall? Any other special requirements to get nice blooms next year? (e-mail reference)

A: I don't know where you live or the soil type you have, so it is difficult to give you accurate advice. Generally, bulbs don't need that much fussing over if they are in halfway decent soil. Watering them through the summer isn't advised because they have very little need for it in most cases. Sprinkling a bulb fertilizer in the fall when the soil cools and new roots are forming probably is not a bad habit to get into. There are several formulations of bulb fertilizer on the market with a variety of names, such as Bulb Food, Bulb Booster or Bulb Tone. Most bulb fertilizers are slow-release types and most have nutrient formulations of 9-9-6, 4-10-6, 5-10-20 or 10-10-20. The common formulation of 9-9-6 is ideal for most types of bulbs, including garden lilies and tulips. Daffodil experts recommend using slow-release 5-10-20 or 10-10-20 for daffodils if it is available. Whatever product you choose, follow the recommended application rates on the package. If you do not have bulb fertilizer, I recommend 2 to 3 pounds of 5-10-10 (a standard garden fertilizer) per 100 square feet for spring-flowering bulbs.

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

NDSU Agriculture Communication

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