July 19, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Could you please tell me when is the best time to plant iris and peony? (Medina, N.D.)

A: Both should be planted in late summer, August to early September. That way, there is ample time for root development before winter arrives.

Q: Can you tell me if seeds from a peony plant will be true to parent? After several years this is the first time ever I have seen a peony go to seed and it is only one plant! (Plankinton, S.D.)

A: Probably not, as most have been hybridized for specific quality traits.

Q: I have three rose bushes that have grown back from last year. None have any buds on them as of yet. The plants all look very healthy. Someone told me that if a rose grows back from below the base of the plant, it won’t blossom. Is this true? That seems to be the case with these roses.

Will they ever blossom or should I just dig them up? (Williston, N.D.)

A: Oh, the problem with partial truisms! The growth from below the base of the plant is from the rootstock, which is used to impart vigor to the scion or budwood. When this dies, the scion "dominance" is removed from the roots, which then produce sucker growth that is extremely vigorous, and generally non-blooming. However, if the rootstock sprouts were allowed to remain, they would eventually bloom, but not with the same flowers of the original plant. Certainly less attractive. In essence, just dig them up!

Q: One of my silver maples looks sick. Could this be caused by weed and feed? Also, should I be fertilizing my evergreens? (Wing, N.D.)

A: Weed and feed applications are a pet peeve of mine for just the reason you are concerned about. I wish the stuff was banned! Evergreens generally don’t need a lot of fertilization. Simply spray with Miracle-Gro when new growth is taking place once a year, if you feel there is a need.

Q: I had a problem with my iris this year. One of the buds would open nicely, but the others would dry up and had a papery texture. Can you tell me what happened and how to keep it from happening again? (Jud, N.D.)

A: It could be aphids or thrips that caused the blossom problem, especially if the rest of the plant appears healthy. In the future - next spring - spray with a systemic insecticide like orthene.

Q: I have a problem with the soil in my yard. We had our house built two years ago and the top soil they left isn’t very good. We have determined that the soil we have is mostly composed of clay. We planted our grass and had a good first year., but this year I just can’t seem to keep the grass growing. The only thing I can think of is that the clay is just packing too tight. It’s to the point that if you try to put a spike into the ground you have to hammer it in. Would this be the problem? I plan on plugging the lawn this year. I hate to have to till up the whole yard to add organic matter to it. How about top dressing with compost? Would that do any good? ( Sioux Falls, S.D.)

A: Your problem is the tight clay, as you assume. Core aeration is the best solution, followed by a light topdressing of sandy loam. You will likely have to do this for two or three years to build up a decent soil for adequate growth of your grass. This is a procedure that has been used many times and has been proven effective through many research trials around the country.

Q: Eleven years ago we dug a very small rhubarb plant out of the prairie by an old homestead. This one small plant is now 15 rhubarb plants with one that grows stalks of rhubarb to 3 feet high. This one plant is by itself in the middle of the yard and we let it go to seed each year as a "show plant." The leaves are always 2+ feet wide and just as long. The seed stalks grow to over 5 feet high and are a creamy white. It is just beautiful. We don't know the variety, but all the plants have more green stalks then red. It makes wonderful rhubarb pie and sauce. Some of the stalks are always 6 to 8 inches around. This homestead belonged to my family, and we all know that the rhubarb had not been disturbed in decades. Apparently some of the old time varieties, or at least this one, didn't need to be dug up and moved every so often. (E-mail reference)

A: Thank you for the information and history of the rhubarb on your family's property! I recently saw some that would equal what you describe on a trip to Alaska--a huge plant, taller than I am.

Q: I have a bed of strawberries, mostly June bearing. The edge of the bed is railroad ties. I have had problems keeping the clover and grass out of it. It seems that as soon as I get it cleaned out it starts all over again! I was wondering if there is any weed killer that would work on the clover and not on the berries, or if there is any other idea that you have. ( Woonsocket, S.D.)

A: Clover doesn't like Dicamba, which is contained in Trimec. CAREFULLY take an artist’s paint brush and dip it into a solution containing Trimec in proper concentration and "paint" the clover leaves with it. You may also follow the same procedure with Roundup, which is also effective on grass and is not soil active. I have nothing else to suggest unless you want to begin all over again.

Q: I have a honeysuckle tree that is about 45 years old. It is falling over, and the base of the tree is rotting out. Two years ago I found these bugs that resemble the lady bug real thick in the base of the tree and thought by killing them I had the problem solved, but now it's falling again. I can take a branch and just pull it right out. Is there any hope for this tree? (E-mail reference)

A: "Lady bugs" come in many forms and may have been trying to get where decomposition was taking place for the warmth through the winter months. Killing them off was a disservice, as they are predators that will control plant destructive insects. They cause no harm to the tree itself.

Anyway, basal rot, no matter what the tree may be, does not bode well for the long-term survival of the tree. There is very little that can be done except to anticipate its eventual demise, and have it removed before it becomes a court case by falling on someone or destroying property.

Q: I have two beautiful fuscia baskets and need to know proper care: fertilize or not, water heavily or not? Also, can I attempt to overwinter them and how? ( Fargo, N.D.)

A: Fuchsias need water daily and fertilization every two weeks or so to look their best. They make poor candidates for overwintering, unless you are planning to overwinter yourself along with the plant, in someplace like Florida! The dry air from the heating system takes its toll on them.

Q: We have peonies that are opening misshapen. There are a lot of ants and flies of many types on the various buds. The flower that is open has black edges and not opening the way others have. Are the ants and flies feeding on the tips before the flower opens? (E-mail reference, Ellendale, N.D.)

A: The peonies are likely suffering from being planted too deep, or someone has pulled soil (or mulch) around the crown that is too thick. This causes the plant to produce flower buds that turn brown and never open, or if they do, are greatly misshapen. Another possibility is a disease known as botrytis, which causes many of the same symptoms. It occurs during wet periods in the spring. Best control is good fall clean-up. The ants and flies are attracted to the sticky secretions that the flower buds produce. It is their form of a "honey" fix.

Q: My grapes have spots on the leaves. Some spots are 1/8 inch or less, round with dark borders and tan centers. As they get larger the tan centers get bigger and the dark border stays the same, Some up to 1/2 inch in diameter. Some have fallen off. Any ideas? (Fessenden, N.D.)

A: Spray with Bordeaux mixture right away to control the further spread of the fungus. I don't know what it is called offhand, but I know it will spread fast, especially in rainy, humid conditions.

Q: Can you provide me with some reasons strawberries don't set fruit? The bed was planted last summer, bloomed and set no fruit last year. This year there was a heavy blossom load but no berries. (Jamestown, N.D.)

A: Many reasons: rain at the time the pollen was ripe, cold temperatures at the same time, windy conditions at the same time so pollinators couldn't get to the blossoms, frost killing the pistillate (female) part of the flower or lygus bugs feeding on the pistillate part of the flower.

Q: I have two semi-dwarf plum trees in my front yard. They are both about 6 feet tall and have been there about two years. In the last few months, they have both been shooting sprouts up into my lawn. These shoots appear mostly within about an 18-inch radius from the trunk. Why does this happen, and is there something I can do to stop it from happening? I'd like to keep them but I don't want them to destroy my lawn or work their way into my plumbing system. (E-mail reference, Pacifica, Cal.)

A: Unfortunately those sprouts coming up from the roots are a big disadvantage of plum trees. You can try placing landscape fabric around the base of the tree to see if that discourages them, but often they come up farther out in the lawn. I had a couple of plums in my back yard that did just that, and when they started sprouting in my neighbors’ yard with them asking me what I was going to do about it. I cut them both down, even though they were both good producers. I fought sprouts from the root system for three years after that!

Q: We have a daisy in its third year. It started very well this spring. We noticed that the plant had what appeared to be fussy cobwebs and the plant began to deteriorate. We sprayed the plant with house and garden bug killer approximately a week ago. This did not seem to do much so far. Is there anything we can apply that will take care of the problem? (E-mail reference)

A: Usually the pesticides formulated for houseplants are too wimpy to be effective on real insect problems for outdoor plants. Without knowing what it could be that you are trying to control (sounds like spittlebug) I suggest spraying with Orthene, a systemic insecticide. That way, as the insect begins feeding on the plant, it ingests the toxin and is killed. Direct contact of the insect with the spray is not necessary.

Q: Can I trim cotoneasters any time, or should I wait until a certain time to trim them?

Also, I have some ash trees in my yard and there seems to be these little white pimple looking things on the leaves. I can't scratch them off and it almost seems to be in the leaf. Is there anything I can do to take care of that problem? (Battle View, N.D.)

A: Cotoneasters respond well to pruning just about anytime except late summer or fall. Pruning now will give the cuts plenty of time to heal before the onset of winter. Often they are given a pruning in the early spring to "freshen" up their appearance for summer growth. Those "pimples" that you very descriptively refer to are really galls that are formed by midges feeding and laying eggs in the very early spring. These galls will not hurt anything. They are simply outgrowths of the insect's activity earlier in the season. Nothing more than cosmetic damage and most likely, will not be there next year.

Q: I want to obtain a very large glass bowl and put fish at the bottom and a plant on the top. Would a bulb accommodate this well? If I put in something like a layer of moss, would that help? I am generally clueless when it comes to bulbs, but I know that there are some that can tolerate rock garden climates. (E-mail reference)

A: I don't know about the fish/plant combo, but paper white narcissi and amaryllis make good bulbs for such planters. Generally, a "rock garden" is established just for physical support, but if you had another means of doing that, that would be acceptable as well. My concern is for the fish. How would the oxygen that it needs get into the water?

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