October 16, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: Last fall I planted 30 peonies in a new bed but now need to move them because of a construction project. I do have the option to do it next spring or this fall. What is my best option? (Bismarck, N.D.)

A: If you can get to it right away, do it now. If you cannot get to it before the end of October, then move them first thing next spring before new growth emerges.

Q: We've had a rubber plant tree for almost 10 years that we’ve kept in the house. The last two years we've put it out on the deck in June. It has thrived with new leaves and grown 2 to 3 feet but it lost almost all of its leaves after a hard frost last week. Can it be saved if we bring it inside? (Brookings County, S.D.)

A: Bring it inside and give it plenty of water and light. It will eventually re-leaf.

Q: Should I clean away all the leaves from my hostas plants this fall? They partially froze so I would like to clean up the beds if it is safe to do that now. (E-mail reference)

A: Go ahead and get them cleaned up or else the slugs will think you have prepared a special winter home for them.

Q: I need to seed the back half of my lawn and didn't get around to planting it during the recommended time. I'm thinking the best way to do it is to dormant seed it. I just want to confirm with you the best time for doing it is late October or early November. You recommend using virgin wood fiber as mulch but I don't know where to find it. Can I use the green fluffy looking stuff that is readily available in stores? (Fargo, N.D.)

A: Later this month or early November would be fine, depending on the weather. The objective with dormant seeding is to get the seed down, begin the germination process with the imbibing of water, but no emergence of roots or shoots from the seed. This is the "priming" stage, so the seed is ready to grow next spring. Make the seed application a little heavier than normal to make up for additional attrition over the winter months. The fluffy green stuff you are referring to is fine.

In fact, there is some on the market that is actually wood fiber.

Q: I need to move some honey locust and bur oak this fall. Honey locust can be moved easily. However, I do not have any experience moving bur oak and understand that they do not transplant easily. I have a Vermeer 44 and will use root fertilizer and apply mulch when transplanting. (E-mail reference)

A: A Vermeer 44 is a good-sized machine to do the job. Whitewash an "X" on the north side of the trees before moving them and make sure that "X" faces north in the new location. A little luck, in addition to what you stated, is all that I can think of for you to be successful.

Q: I’ve had a jade for about six years. It started flopping over after I repotted it in a huge pot hoping that it would become a tree. I tried to force it to stand up with wooden sticks supporting the main stems. When I removed the wooden sticks, the stems started breaking at the base. I don't want to give up on this plant because there are new buds and the leaves look healthy. (E-mail reference)

A: A floppy jade is the result of too little light. Probably too late for it now, but try moving it into a brighter location and see if the plant improves at all over the next six to eight weeks.

Q: We have five cottonwoods in our backyard that are 75-to 100-feet tall. They provide good shade but they started dropping leaves in August for no apparent reason. The leaves that are falling have a gall on the leaf stem. Inside the gall are some sorts of little critters. The leaf problem is so severe that we are considering having them cut down. (E-mail reference)

A: Please don't sacrifice those mature trees for the small problem you have. Contact a Certified ISA Arborist and have the trees sprayed next spring. The petiole gall forming insect is an aphid that causes no harm to the tree other than premature defoliation. The arborist will very likely come out next spring before leaf bud break and spray with dormant oil and possibly follow up with an approved insecticide. It could very well be the only showing of this insect, as natural predators may move in and keep them under control next year. Generally, an early dormant oil spray will take care of any remaining insects. Try to clean up as much of the fallen leaf litter this autumn as possible.

Q: I grew green beans (bush variety) this summer. The first picking was good. After that the blooms would start to form and then disappear. I have been told that I had soybean beetles. If it is true, are they in the soil? Should I work insecticide into the soil now or in the spring? What should I use next summer so this does not happen again? Thanks. (Mina, S.D.)

A: I am loath to recommend any insecticide at this time of year. I would suggest rotating the planting site with something not related to beans and then monitor next spring for any beetle activity. If you find some activity, spray with the least toxic, environmentally friendly material available.

Q: Which perennials should be cut to ground level in the fall? Specifically tall yarrow, purple coneflower, mums, and garden phlox. (E-mail reference)

A: The guidelines depend on where you live. In North Dakota, we like to let perennials remain with the flower stalks to help trap snow. Cut them back in the spring before new growth begins. I suppose in the more southern regions of the country trapping snow is not a concern while a neat looking perennial flower bed is, so cutting back in the fall would be appropriate.

Q: Is it possible to raise Frasier firs in northeast S.D.? (Sioux Falls, S.D.)

A: Yes, as it is in zone 4, which is the high end of this plant's hardiness zone. I will be very jealous if you succeed because they are one of my favorite trees! It would need supplemental irrigation and spraying of the foliage during hot, dry periods in summer, which shouldn't be a problem. But watch out, they develop into beautiful Christmas trees so people have been known to steal them right off the stump. Some way to celebrate Christmas -- presents under a pirated tree!

Q: How do I kill my hostas? I dug them up as deep as I could but everyone keeps telling me that they will come back and I won?t be able to get rid of them. Is this true and what suggestions do you have to prevent this from happening? I would like to know before I plant new shrubs in that spot. (E-mail reference)

A: They are like any other lily, if you leave anything behind, it will sprout and grow. If you did a good job of digging them out, they will be gone. If an occasional loner should show up, it can be dug up or wiped out with Roundup.

Q: I have a schefflera, which I have been growing for a couple of years. It is healthy, looks beautiful, and continues to grow at a steady rate. Last spring I decided to prune the plant. I put the branches that I pruned in water so they might sprout roots. Over a year later, the branches have sprouted roots but at a very slow rate. Is there a way I can influence them to grow faster and begin to sprout other branches and leaves? (E-mail reference)

A: Get the rooted cuttings out of the water and into some potting soil! Water alone will not sustain or encourage new growth. Schultz's potting soil would do the trick, as it is rich in organic matter and has a starter nutrient formulation mixed in.

Q: I'm giving up on my garden. I'm going to make it lawn next year. Any recommendations on how to remove the weeds before seeding? Should I seed now or wait until spring? (West Fargo, N.D.)

A: Get the seed down now. Dormant seeding now will get everything primed and ready for next spring's emergence.

Q: When is the best time of the year to cut cranberry bushes back? (Linton, N.D.)

A: I am sure you mean the American cranberry bush viburnum. The best time is early spring, before leaf-out, if flowering and fruiting are not important for that season. Otherwise, do it right after blooming.

Q: I would like to keep my geraniums over the winter. Can I put them in the basement? Should I cut them back this fall or wait until spring? How much do I need to water and when? Also, can begonias be kept inside and replanted in the spring? (Edgeley, N.D.)

A: Cut the geraniums back and bring them inside, without the dirt and pots. Keep them in a cool location such as the basement and in a netted bag. Check them monthly for wrinkling. If they are wrinkling, dip them into tepid water for about 10 minutes to rehydrate. In February, repot and place in a sunny window or under grow lights. If your begonia are the fibrous rooted type, they can be brought indoors and grown as potted plants because their demand for light is not as high as geraniums. If the begonias are the tuberous type, you are better off letting them dry down and storing the tubers in a cool location for most of the winter. Repot them in February and give them the same treatment as you would your geraniums.

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: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu