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Published January 06, 2012, 12:00 AM

Hortiscope: Repot, prune poinsettia 8 to 10 weeks before Christmas

Q: I live in the tropical country of Indonesia. In my country, we have dry and wet seasons. The temperature is similar throughout the year, between 77 and 86 degrees. However, there is more sunlight during the dry season.

By: Don Kinzler, INFORUM

Q: I live in the tropical country of Indonesia. In my country, we have dry and wet seasons. The temperature is similar throughout the year, between 77 and 86 degrees. However, there is more sunlight during the dry season. I just bought a beautiful poinsettia for the Christmas season. Is it possible to keep the plant blooming throughout the year? The poinsettia is in full bloom. How long will it stay red? I am wondering whether I should put it in a daily 14-hour dark routine or leave it alone. (email reference)

A: Poinsettias on the market these days will hold their red bracts (leaves) for many weeks past the Christmas season. Generally, the best thing to do as the plant begins to look unattractive is to plant it outdoors in a protected, somewhat shady location. In eight to 10 weeks before Christmas, repot the plant and prune it to the size you want. After that, begin subjecting the poinsettia to 14 hours of daily darkness in a cool location. When the bracts begin to show color, you can scrap the darkness routine and enjoy the plant as it develops into full color. In your part of the world, there is a lot of playing around you can do with this plant. You can take cuttings from it halfway through your growing season and root them. Treat the cuttings the same way you would the mother plant to get the foliage to produce color. You can give the new plants to friends or spread them around your property for added holiday decoration.

Q: My large, thriving spider plan turned brown in a week, so I repotted it. It was all roots, so I think it clearly needed to be repotted. I put it in a good-sized pot, although it doesn’t have drainage. I figured it was OK because there is no way the roots will sit in water. I give it just a bit of water when needed. However, the plant is dying, so I put it outside. However, it does have a bunch of babies. Should I take the babies and root them or should I save the momma? Should I bring it inside? Does the plant need fertilizer, drier soil or more sun? (email reference)

A: Save the babies first. Get them removed from the mother plant and work on getting them rooted. Next, take the mother plant out of the pot and split the crown in half to see if there is any living tissue. If not, then dump it and work on perpetuating the offspring. This plant needs to be in a container that has free drainage. They can take moisture and tolerate dryness. Spider plants also can live with air pollution, but they cannot tolerate a poorly or nondraining container. I think something was dumped on the crown of the plant because it is dying so quickly. Generally, disease and insect problems don’t work that fast to destroy a plant. Usually, disease and insect problems kill one part of a plant at a time until the entire plant is wiped out. Stop and think back to just before the plant went downhill. Did anything strange happen to or around the plant? Did you throw a party where alcohol was served? These are pretty tough plants and are used by NASA to clean the air in space station settings, so what you describe is quite unusual. Sorry.

Q: We have a 30-year-old jade plant that has a V-shaped trunk. It is adjacent to our office building, so only one side receives sunlight. The plant possibly was overwatered. One of the trunks has suffered enough rotting that I could fit half of my wallet into the trunk. The rotting occurred on the side that faces the building. The leaves are plump and the flower buds are sprouting. We turned the plant around so that the rotted side faces the sun and will cut back on the watering for a month. Are there any other measures that we should take to help the plant grow? Should we split the plant in two? Would you recommend cutting the rotted trunk off to save the rest of the plant? (Irvine, Calif.)

A: You are in Orange County, which has an excellent county Extension agent and a bevy of master gardeners who could assist you. It looks like it is in need of fertilizer and the rotted area probably should be cleaned to keep it from spreading. Only an on-site examination can make a valid determination. Go to http://ceorange.ucdavis.edu/ to find an Extension agent near you. Very likely the Extension agent will make the visit or request a master gardener to do so.

Q: I’m trying to find out what’s wrong with my hoya plant. I have a hoya carnosa plant that I inherited. It is about 75 years old. It bloomed for the first time about eight years ago and has bloomed every year since then, except for this year. The leaves are dying and I never have seen the plant so sparse. There are some fresh, dark leaves at the top. I keep it in a bedroom next to a window, so it gets moderate, indirect sunlight. I water it lightly about once a week. From the questions and answers I’ve seen on your website, the idea hit me that it might need to be repotted. It has been in the same pot for as long as it has been in my care (seven years) and for as long as I can remember before then. Do you have any ideas? Should I change its location? Should I water the plant more or less? If I repot the plant, when is the best time to do it and what soil should I use? I’m terrified that I might kill the plant. (email reference)

A: Hoya plants do not like being moved. They are quick to pout by doing what you have described. They need bright, but indirect light. Do not put the plant in direct sunlight, especially in the summer months. It usually declines and dies when it is overwatered or watered with cold water. Hoya plants get along quite nicely with people who like to keep their house temperature between 70 and 72 degrees. My suspicions are that the plant was moved and that your watering has not reflected the need for a new watering routine. Water the plant only when the soil is dry to the touch. When growth is noted during the spring and summer, the watering cycle can be increased to keep the soil moist but not overwatered. Only repot when the plant is dormant. Move up to a pot the next size larger. Going to an overly large pot will result in overwatering problems. Any good commercial potting soil, such as Miracle-Gro, is acceptable. Be sure the pot it is in has a drainage hole. To keep the soil from washing out, use a paper coffee filter to cover the hole or place a flat stone over it. You can take tip cuttings from the ends of the branches and root them. Because hoya plants root easily and often save a plant that is in decline, I encourage you to do the same. Take cuttings from the tip of healthy stems. The cuttings should be about 3 inches long. Place them in a pasteurized medium to root. I don’t know if all of this will save your plant, but it is the best advice I can come up with, considering the information you’ve provided.

Q: We’re fans of your Hortiscope column and have a question for you. We moved to a different city last fall. The city had lined the streets with large ash trees a few years back. However, they are now dying. Our neighbor lost his on Memorial Day during a windstorm. Most homeowners have started to cut their ash trees down. In helping our neighbor clear his ash tree after the storm, we noticed what looked like worm paths throughout the tree. Now our ash trees appear ill.

On advice from my father, we sprayed them with Malathion this summer. However, there appears to be no benefit from these applications. I’ve attached pictures of the one tree next to the driveway. I fear it might be too late for it, but we still have one that does not show too much damage. Is there anything we can do to save our last tree or any of the neighbor’s trees? Also, we have planted Redmond lindens and cathedral elms elsewhere in the yard. Are they in danger of dying? If so, how can we protect them? Can you recommend a good replacement species? (Reiles Acres, N.D.)

A: Thank you for being fans of Hortiscope! Have you notified the city forester of this rather fast decline of the ash trees? If not, then I’d suggest getting in contact with the forestry department at your earliest convenience. There are several borer insect species that will attack ash trees and girdle the cambium under the bark, causing the tree’s decline and eventual death. With the exception of the emerald ash borer, which has not been reported anywhere near our region, most pests will attack trees that are under stress. This necessitates discovering what is causing this stress. It could be compacted soil or the tree was planted too deeply. The root area may have been flooded for an extended period of time or there was a change in the water table. There could be many more possibilities. Most trees can be protected from extensive borer damage by using a systemic insecticide. This is applied around the base of the tree early in the spring as new growth is beginning. It is taken throughout the vascular system of the tree, including the cambium. As the insect larvae begin feeding, the poison goes to work on them. This systemic material can be used on any tree that is not a fruit-bearing species. You can use it on your lindens and elms if the need is there. I hope this information helps.

Q: I have a small nursery about 15 miles southeast of Denver. The spruce trees we purchased as seedlings are growing well. However, why have some of the trees gone more green than blue? It also appears the trees that were really blue earlier in the year now look lighter. I have been told that acid in the soil might be the cause. However, no one seems to have a solution to get the trees back to the more blue color. Any ideas on how to correct the problem? (email reference)

A: You are witnessing the phenotypic seedling variation that is giving you the range of color possibilities this species possess. If you were hoping for a true blue that would retain color throughout its life, then you would need the grafted or clonal stock. They have names such as Picea pungens ‘Glauca,’ Picea pungens ‘Koster’ or Picea pungens ‘Hoopsii.’ When you purchased these trees, if they did not have these name tags, then all you got were seedlings that come with their color variability. I don’t know of any adjustment in fertilizer practices that can get you the color consistency you are looking for. Sorry!

Q: We have had a ficus for about 15 years. It has flourished and grown to more than 10 feet in height. I was away on business when we had a hard 17-degree freeze. My wife could not get the tree inside the house because it is so large.

All the leaves are falling off and it looks bad. Did we kill the tree? (email reference)

A: A temperature that low will do a good job of quickly killing most tropical plants. Whether it is dead or just injured from the cold depends on how long the exposure was to the subfreezing temperatures. If it was for about an hour before sunrise, then there is a chance it is injured and not dead. It also depends on whether the plant was well-hydrated. If the main stem appears to be mushy, then the freeze did it in. If the stem is firm and it is just the leaves showing an impact, there is a chance for recovery. It then depends on whether you have the patience to wait for the plant to become something attractive again. If not, then dump it. Put the replacement ficus in a container that has wheels so it can be moved indoors when the weather threatens.

Q: I have a very large willow tree in our front yard that I planted about 15 years ago. I cut off a low branch years ago, but I just noticed that at the point of the cut, there is a lot of soft wood that goes fairly deep. I do not see any bugs. The tree still looks very healthy. Any ideas what I should do? (email reference)

A: Soft wood at the site of the cut is not a good sign. It sounds as if the branch was cut back too far into the main trunk of the tree. The cut has inhibited proper healing and compartmentalization of the pruning wound. It is difficult at this point to do anything to correct this problem. You have two basic choices open to you. The first is to contact your University of Georgia county Extension agent to see if a visit can be made by the agent or a master gardener. To find the nearest Extension agent, go to http://extension.uga.edu/about/county/index.cfm. If that doesn’t work out successfully, then I’d suggest contacting an International Society of Arboriculture certified arborist to inspect the tree to see if anything can be done to prevent any further decay. To find a certified arborist, go to http://www.treesaregood.com/findtreeservices/FindTreeCareService.aspx. There also is a flier showing how mature trees should be pruned. To read it, go to www.treesaregood.com/treecare/pruning_mature.aspx.

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 email ronald.smith@ndsu.edu.

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