Q: I have a healthy ficus that was taken over by spider mites that moved over from an ivy plant. I got rid of the ivy, but hope I can save my ficus. What is the best way to get the mites off the plant? (e-mail reference)
A: If you can, put the plant in the shower and hose it down with a hard spray of water. Be sure to spray underneath all of the leaves as well. Follow this up with some insecticidal soap in places the mites still might be evident. Light infestations are relatively easy to control when caught early. Heavy infestations usually result in the plant needing to be thrown away because the spider mites' reproductive cycle gets ahead of one's ability or interest in controlling the mites. Let this be a warning on future plant acquisitions. Carefully check a plant for pests before buying or accepting a plant as a gift. Keep the new plant isolated for a few weeks to be sure you are not introducing a new pest to your other houseplants.
Q: Last year, I started dwarf marigolds from seed under grow lights. I grew many healthy plants. I donated about half of them to the flowerbeds at Trinity Lutheran Church, where they thrived. The other half I planted in my garden. They all took hold, but several weeks later, the whole batch was eaten by some kind of pest. The pests ate the leaves, leaving only the veins, but then the veins disappeared. I read somewhere that thrips and some other pest can do this. What can I do to prevent this in the future? It there a spray I can use? The bugs also attacked my amaranthus in much the same manner. They ate large holes in the leaves and eventually the plants died. I had no problems the previous year and am wondering if I can expect problems this coming year. (Moorhead, Minn.)
A: This sounds like your home plantings got devastated by some larval stage of an insect population. Assuming you completely cleaned up the planting area, the likelihood of these same pests returning is greatly reduced. I would suggest that you monitor the plantings every day to check for any initial feeding activity. You might put out some sticky traps in the planting area to see what you catch. This will give you a leg up on the voracious youngsters that may be arriving a few weeks later. When the initial damage starts to show up, get an appropriate insecticide and go to work!
Q: We had raspberries in our backyard in south Fargo while growing up. I am now living in Gardena, Calif., and want some here. I bought Caroline raspberries in May 2008, but they died. A new sprout appeared in November, but it does not look healthy. A local nursery has heritage raspberries. The person at the nursery says heritage will work in this climate. However, according to the Gurney Nursery Web site, Caroline raspberries have a greater southern zone range than heritage raspberries. Is heritage more robust than Caroline or do I have a soil problem? I am skeptical that the heritage plants will work. (e-mail reference)
A: I would trust the local recommendations. If the nursery stock is regionally grown, it is a good bet that the proprietor is selling something that is dependable and should do well. My opinion is that buying something through the mail is OK when trying something new and not available locally. If something you want is available locally, then go for it, especially if it is a locally owned garden center or nursery. It's in business to satisfy customers and stay in business.
Q: When reading your Web site, you said that red cayenne, jalapenos or habanera fresh peppers could be used to prepare a rabbit repellent. However, you said be careful if you use habanera because the capsaicin concentration is high enough to cause serious damage to the preparer! You went on to say, "Jalapenos should be hot enough to keep the bunnies away. The quickest way to come up with a concoction is to take three fresh peppers and run them through a food processor with enough water added to create a liquid. Pour the liquid through a cheesecloth mesh into a glass quart jar. Add about 2 tablespoons of olive or other vegetable oil, a squirt of Elmer's glue and a drop or two of liquid dishwashing detergent. Use one part of the concentration to 10 parts water. Shake well just before applying. This should discourage the bunnies without hurting them. If not, then make the concentration stronger (30 percent) or use cayenne peppers for extra heat. Be sure to reapply after new growth appears or after a good rain." Is this something that I should squirt directly on the leaves of my euonymus plants? Should I use a squirt bottle? Rabbits ate three of my euonymus plants down to the twigs. We've had an unusually snowy winter in Buffalo with no melting because of the very cold weather. I guess the rabbits only could find my shrubs in this deep snow. Will these shrubs survive? (Buffalo, N.Y.)
A: In most instances, if the plant was healthy before being gnawed down by the rabbit, the euonymus or any other woody plant shrub should recover. Spraying the pepper mixture directly on the plants you want to protect is a good idea, but you need to remember to repeat this several times during the winter becasue it dissipates and washes off. I have found the best way to keep the bunnies away from my woody plants is to feed them like birds. This makes it easy for them to find something to eat and cuts down on their scavenging somewhat. They actually look fat and healthy this winter, even though this is one of the worst winters we've had in a long time. I figure some fortunate predator will appreciate their plumpness at some near future date!
Q: I have 33 emerald arborvitaes, but deer have eaten almost all the green foliage. There is about a foot left at the top of each plant. What can I do to save them? (e-mail reference)
A: Try to come up with a way to keep the deer from feeding. This might call for using an exclusion fence along with all the other repellents, such as human hair, Irish Spring soap, wolf urine or Hinder. Assuming you are in the northern part of the country, you can't do much until spring weather arrives. At that time, examine the plants to see if there is any sprig of green left on the plants. If so, then the plants may recover, but it will be slow. If there is no green, then you might need to consider removing them and replanting. This time, take all the steps necessary to keep the deer away. Unfortunately, this could turn out to be as big an investment as the replanting.
Q: I was given a Christmas cactus more than 15 years ago that already was more than 20 years old. The person who gave me the plant said the plant never bloomed in the more than 20 years he had it. Within two years, I was able to get it to bloom during the Christmas season. It is getting very large and I would like to repot it and split the plant. Is this a wise decision? If so, how do I split it? Also, is there any way that I could determine the approximate age of this plant? People often remark about its size and beautiful flowers and ask how old it is. Your Web site is wonderful and very helpful to someone who can grow plants outside, but inside is a real problem. (e-mail reference)
A: Christmas cactus blooms better when somewhat pot-bound, but eventually will need to be repotted. Use a well-draining, peaty soil mixture. The best time to repot is after blooming is complete. Test the drainage by running water through the pot to make sure it quickly drains. It is best to use a pot that is one size larger than the previous pot. Lightly scratch or roughen the edge of the soil to encourage root formation. If it is presently growing in a clay pot, it is a good idea to use new clay pots as well. Divide and repot the plant when spring comes around in March or April. Take the root mass, cut it into two to four sections and repot. If you are afraid to do this, then just move the whole plant to the next size larger pot. Good luck with trying to determine the age of the plant. I don't know of a way to determine the plant's age and can't find any information on the subject. From what you told me, you could say that the plant is approaching 40 years of age. Even if you are off by a few years, this still should impress most people.
Q: I moved into our home last July. The house is in front of a wonderful lake that is overgrown with trees. From our upper-level bedroom window, I can see two beautiful white birch trees. I have fallen in love with these trees, but they are growing on the other side of the lake. I would love to have some planted in front of our home or a little closer so I can view them in the summer months when the other trees are full of leaves. I would like to know if there is a way to harvest seedlings from these trees. What would be your recommendation? I'm trying to do this on a low budget for my personal pleasure and those I share my life with, so any help you can provide would be greatly appreciated. (e-mail reference)
A: You are to be commended for being interested in your natural surroundings, especially the white birch trees. Growing them from seed is the way to go. Birch seeds have a low viability, so collect a handful of seed and sow the seeds lightly over the surface where you want them to grow. The seeds need light to germinate, so don't bury them too deeply. Do this in the fall prior to snowfall. You should see some results the following spring. This is about the lowest budget approach I can think of. Good luck and enjoy!
Q: We have a beautiful, tall spruce tree that is anchoring a portion of our home's landscaping. During high winds, the tree was partially blown over. I estimate it is leaning 35 degrees. The root ball is not exposed, but the ground around it is humped. I would like to winch it back in place and secure it with cables until the root system can regenerate. Am I wasting my time or can this succeed? Can you recommend soil additives to help with root growth? (Fort Wayne, Ind.)
A: No soil additive is needed, but get to the task as soon as possible. You might check with a local certified arborist to see if someone can accomplish the task quicker and with more expertise. Trees like this have been saved in the past, so don't give up!
Q: I purchased three tulip bulbs in a tiny pot. The leaves have formed, but no flowers. I thought the pot looked too small for the three bulbs, so I transferred them to a larger pot and added more soil. Soon after, one turned yellow and flopped over. A few days later, the same happened to another plant. There is one plant left, but I don't know if it will survive. What did I do wrong? (e-mail reference)
A: It sounds like you purchased some blind bulbs. These are bulbs that produce foliage, but no flowers. This could be due to a number of reasons, such as insufficient cold treatment or foliage not left on long enough the previous season to get a flower bud started. Another possibility is physical damage from rough handling or disease and insect activity. You also shouldn't have assumed the bulbs were too crowded in the pot.
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 firstname.lastname@example.org.