April 12, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Our garden club has a garden plot that features a five-pointed star in the center. This year we're planning to use Antigua yellow marigolds in the star and surround the star with purple and lilac wave petunias. What's a good spacing for wave petunias for optimum coverage, and might we have a problem with petunias taking over the marigolds? (E-mail reference, Baudette, Minn.)

A: The petunias will grow into the marigolds, but not over them. I would space them about 2.5 feet apart and they will shortly grow together, making a dense and probably weed-free mat.

Q. I have a dwarf tangerine plant growing in house. It's about 2 1/2 feet tall. Should I let it grow taller or can I cut it down so it will extend to the sides? It has only one stem or trunk with no side shoots. (E-mail reference, Hague, N.D.)

A: Yes. Simply cut it back to just above where a leaf is growing. Don't cut back any more than one-third the length of the stem for now. Be sure to give it as much light as possible.

Q: I have tried twice to keep a Bonsai juniper tree; both times, the needles turned brown and the tree died. I mixed a small amount of liquid plant food with the water. It sat on my kitchen table getting the morning sun, once during the summer and once during the winter. It dies way before it is time to trim the roots. Can you help me with any suggestions on how to keep it green and alive? (E-mail reference, Aberdeen, S.D.)

A: I'd suggest getting a grow light on a timer and having it on for 12 hours a day. I would also get some distilled water (or reverse osmosis water) and use that for misting and watering on a regular basis. Misting should take place several times a week, daily if possible. Watering should be once a week, with a good soaking with the same water. Fertilize lightly twice a month.

That's pretty much the regime I follow and it seems to work on my Bonsai.

Q: We recently purchased a contorted filbert. What type of fertilizer or plant food should we use and how often? Can the suckers be dug up and transplanted? Are catkins the little green things that hang down from the branches? What is their purpose? (E-mail reference, Gilbertsville, Ky.)

A: I wouldn't worry about fertilizing this tree, unless you have it growing in a container. Then it should be a complete fertilizer like Miracle-Gro once a month. Otherwise the tree will do just fine in the soil that it is planted in. I would water only when or if, the plant shows some nutrient deficiency symptoms. Yes, the suckers can be dug and transplanted, but being a grafted plant, you will not getting the same thing. Suckering is one of the problems with this plant. Yes, those are male catkins hanging off the branches. They serve as a source of pollen for the female flowers, which almost never show up, so their purpose is mostly ornamental. Don't hope for any filberts! This is also known as Harry Lauder's Walkingstick. It was discovered in 1863 at Frocester, Gloucestershire, England, in a hedgerow.

Q: I have a hydrangea plant that I bought in a house plant pot. I have had it for two weeks now, watering it once a day. The plant looked great up until three days ago. What are the basic care dos and don'ts of this flower? I heard it’s almost indestructible, but it's dying quickly. (E-mail reference)

A: Basically, your plant needs bright, indirect light, regular watering enough to keep the root ball from drying out, and fertilizing every two weeks. You may have the plant in a non-free-draining pot. If that is the case, repot immediately in one that drains freely, dumping excess water out of the saucer 20 minutes after watering.

Q: I just bought a new home and have a plant coming in. I don't know what it is. A friend thought possibly it could be a peony. There are a cluster of red bulbs (dark, maroon in color) sticking straight out of the ground. There is space ( an inch or more) between each one, like it might be a bush or large plant. The bulbs have not yet opened, and I'm not sure if the color will remain red or not. Do you have any guesses? (E-mail reference, St. Louis, Mo.)

A: It does sound like you are describing a peony. The buds should break and new growth emerge as soon as the weather in your region warms consistently, which is way ahead of us here in North Dakota! The only other possibility could be crocus or other early flowering bulbs, but my vote is for it to be peony.

Q: My husband and I started a new lawn last August and are wondering what the first step would be for it this spring, because we have several problems. First, last summer we had black dirt and we had millions of these little brown bugs. They reminded me of sunflower mites. Some people called them soil bugs. In the fall they would get into my home if I opened the windows in the evening. I'm talking hundreds of them in my home, and they were very bothersome. They could get right through the screens in the windows. We planted trees, and whenever I would water them, those little brown bugs would surface on the rocks around the trees and there were just thousands of them. Do you know what these might be and are they harmful? Second, when we started moving dirt around to get the ground level for seeding, we saw a couple of grubs. I'm pretty sure that’s what they were, because they were white, fluffy worms and we were told they are a problem around our neighborhood. Therefore, we feel we should treat them early enough this spring before they start chewing off our newly planted grass. Third, because it is a newly planted grass, it is sparse in some areas and also very weedy, so we feel we will need to spray for weeds soon. We know that people fertilize their grass very early in the spring, too. So, as you can see I have many concerns and questions as to where to begin, and I feel very overwhelmed by it all. Based on these circumstances could you please tell me what you think is the best thing to do first, and the steps I need to take this spring to have a nice-looking lawn this summer. We do have a sprinkler system and we planted a Kentucky bluegrass mix from a seed house in Bismarck. (E-mail reference, Napoleon, N.D.)

A: Those troublesome gnats will probably be gone this spring. First things first. Yes, there will be plenty of weeds, but not nearly as bad if you had tried to plant the grass in the spring. Activate your irrigation system in May, not April. Water only if the grass needs it. When you mow the lawn for the third time this spring (at 3 inches, by the way) then you can apply a broad-leaf herbicide to control your weeds. A week on either side of Memorial Day weekend, apply some fertilizer, the lawn type, such as 28-3-6 or something similar. Right around the same weekend would be a good time to apply some grub control. Several products on the market can be watered in with your irrigation system. Grubs are a reality in everybody's lawn, so don't worry about them, as there are natural predators that often keep them in check. Manage your irrigation system so that you are applying about 1 inch of water per week either through rainfall or irrigation cycling. This should be enough to keep the lawn green and healthy. Since you have an irrigation system, make another application of fertilizer--lightly this time, about 0.75 pounds of actual nitrogen per1000 square feet. Around Labor Day weekend, again apply herbicide as needed in troublesome spots and over-seed as needed. Another application of fertilizer at this time would also be good, at the same rate as your first one. If those pesky bugs return this spring, catch some, preserve them in denatured alcohol, and send them to me for ID. We can then figure out what to do with them.

Q: I have noticed you get a lot of questions on cyclamen. I don't have the greenest thumb in the world, but love plants. My husband gave me a cyclamen for Valentine’s this year and it stayed pretty for a couple weeks, then after the flowers slowed up the leaves started to turn yellow. What can I do to save my cyclamen? (E-mail reference, St. George, Utah)

A: Cyclamen plants are beautiful to get as gifts but require a little more than average attention for continued blooming cycles. Since yours is already in a state of decline, slow down on the watering until the leaves completely turn yellow and dry up, then stop the watering completely. Store the plant in a cool, dry place until early fall when signs of new growth should begin appearing. Knock the soil off the tubers and repot in the same pot, using a soil based potting soil. Set the plant in a bright light location and begin watering from the bottom of the container--never over the top. This is best accomplished by dipping the pot in a water-filled bowl, allowing the water to seep in until the soil is wetted completely. Then allow the pot to drain. These plants are challenges for even experienced commercial growers to tackle, so don't be too discouraged about this if yours fails.

Q: When we bought this farmstead it was over-run with dandelions and nothing works on them except 2,4-D, so my husband has been spraying them every spring and fall. We feel like this year we will be close to having control. We have more than five acres of grass so there is no spot spraying or hand digging except in the vegetable garden. How long after he sprays do I have to wait before using the grass clippings as mulch in my vegetable garden? I know 2,4-D can stay in the ground a while, but will it be on the grass leaves after a few weeks and some spring rains? (E-mail reference, Carrington, N.D.)

A: Give the grass about three mowings after the 2,4-D has been applied. Any residue should be gone or broken down by sunlight by then.

Q: I read not to use dog manure in a compost as it may carry disease. Yes or no? Also, should cow or other manure be aged or can it be fresh? I know that commercial fertilizer can be used as a replacement. (E-mail reference, Fessenden, N.D.)

A: If it did carry disease, a "hot" pile of compost would kill the organism as the temperature gets to 140-160 degrees F. Never use manure fresh. Salts are too high and the carbon/nitrogen ratio could be a problem, tying up the available N, causing chlorosis.

Q: I received a catalog that features dwarf citrus trees for home and garden. They list three trees, Kaffir Lime, Meyer Improved Lemon and a Washington Navel Orange. The catalog states that the trees are easy to grow indoors, and you can move them outdoors during our summer months. Eight- to12-inch branched plants are available for $26.95 each. Do you think I would have any chance of getting one of these trees to grow indoors? Are there special requirements for citrus trees? Are they available at our local nurseries? (E-mail reference)

A: Yes, citrus can be successfully grown indoors with supplemental lights and summered outdoors. Simply treat them like any other houseplant that requires high light intensity and ample moisture, along with regular fertilization, and everything should be all right.

Q: We moved to North Carolina on the coast and I have been told I will not be able to grow lilac here. Do you know of any reason why they would not do well here? (E-mail reference, N.C.)

A: Sure. It is called high humidity, which would lead to mildew, both the powdery and downy kind that would devastate any lilac plant. You can, however, grow something that is equally as beautiful, and that is the Crape myrtle - Lagerstroemia indica. It has lilac-like blooms and interesting exfoliating bark. I really loved those plants when I lived in the south. There are dozens of cultivars that you can select from. Plant these, and you'll never miss the lilacs.

Q: I have a Swedish ivy that isn't exactly flourishing. I put it out in the late spring, and by the time I bring it inside in the fall, it looks lovely. But over the winter it grows spindly and the leaves get dark brown dried- up edges, or get yellow and fall off. I have it in a bright, sunny window and do not over water (perhaps under water). I do not let the roots sit in water. Second, I have read that rosemary plants can be transplanted in the fall and brought indoors to overwinter. I have tried this two years in a row; the first year the rosemary was in a pot and did very well outside. I brought it indoors pot and all, and within a short time the bottom part of the plant turned a grayish-green, which quickly spread to the rest of the plant, killing it. The second year, I had rosemary in the ground and transplanted it into a pot to bring indoors, and the same thing happened. What am I doing wrong? (E-mail reference, Jamestown, N.D.)

A: All one can hope for through our long winters is for plants first to survive, then recover during the summer. Your Swedish ivy apparently doesn't like the drafts from the window, the salts in the water, or the dry winter air that is the result of our heating systems needing to be used. All of these things could be the problem, or just one of them. I wouldn't suggest bringing the rosemary indoors during the winter. Mulch it heavily outside for the winter, and it should survive, if you got one of the hardy cultivars like 'Munstead'. The very same reasons for your Swedish ivy not doing well (plus possibly some spider mites damaging them) are killing your rosemary.

Q: People have been telling me for years that it is the female cottonwood tree (if there is a male and female cottonwood) that produces the dreaded cotton. If this is true; is there any way of telling which tree is male or female? This would save a lot of grief in unnecessarily destroying the volunteers which pop up on occasion. We like cottonwoods; just not the cotton. (E-mail reference, Wessington Springs, S.D.)

A: Yes, what you said is true. What you want to purchase is a male clone, like the 'Siouxland' poplar. As far as I know, there is no observational way to distinguish the sexes until it is too late.

Q: Here is the scenario: north shore of a lake, house built on a bluff, erosion under deck necessitating stone riprap. The plain rocks look rather utilitarian. Any ideas what to plant that will in time soften this? Riprap total is about 70 feet long and maybe 12 feet wide. (E-mail reference, Erhard, Minn.)

A: Yep, you bet! Daylilies. You can't beat them for "softening" something like this. Of course, the more the site is shaded, the fewer flowers, but they will grow and gradually spread, helping to hold your riprap together.

Q: I have a large raspberry patch that is being plagued with a black bug. Can you tell me what I need to do to get rid of them? I have customers waiting for these berries, so I don’t want to lose them. (Frazee, Minn.)

A: The sap beetle or picnic beetle can be a pest to berry growers. I would suggest control with insecticidal soap as soon as the berries begin to color or the beetles appear. This is an organic approved spray that is harmless to warm-blooded animals. This way, your clientele don’t need to be concerned with any toxic residues.

Q: Over the past two or three years my lawn has become quite bumpy. Since the problem covers the entire lawn, it doesn’t appear to be rodent related. Do you think it could be caused by earthworms? (Mandan, N.D.)

A: Yes, and you should consider this something of a compliment! The worms have found your lawn so perfect that they have multiplied. There are some steps you can take: Roll the lawn this spring prior to mowing with a ballast roller. Run a power rake over the lawn after it greens up.

Apply Sevin soil insecticide granules as if you are treating grubs. I would suggest starting with rolling to see if it works, then try the other steps if it doesn’t.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu