NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
March 2, 2000
Ron Smith, Extension Horticulturist
North Dakota State University
Q: I am having some problems with my variegated red bougainvillea and I am hoping you can help me. What can you tell me about the flowers on the plant? It blossoms indoors, but the flower inside the blossom doesn't have a chance to blossom because the flower falls off too early. Is it not getting enough sunshine? When I take it back outside this summer how should I go about doing it so that I won't shock the plant? My plants are only 2 years old. When do they start getting thorns?
Also, what can you tell me about butterfly bushes? Do I always cut them back in the fall? How far back do I cut them and if I didn't cut them back in the fall, and I should have, can I cut them back in the spring? They are about 2 feet tall now.
And finally, one more question. My white butterfly bush grows bigger than my dark purple one. Is this normally true or could it be that one gets more sun? (Middleport, N.Y., e-mail)
A: The "flower" is actually a bract, which is a modified leaf. The true flower is insignificant and atrophies quickly after opening. The fact that the plant is dropping bracts quickly is an indication of variation in watering. Generally, the bougainvillea prefer dry soil when blooming. Allow the plant to dry out between waterings. They need as much sun as one can provide, and just enough water and fertilizer to keep them alive--not an abundance of either one. Condition the plant to moving outside by setting it out in the sun just for a half hour the first day, 40 minutes the second day, 50 minutes the third and so on. It could be that you have a thornless form (labeled "inermis" on the tag), which is great because those thorns can give a vicious scratch.
As for the butterfly bush--Buddleia davidii--cut it back in the spring before new growth begins, as short as you would like. It flowers on new growth, so if you cut the spent flowers back, it will continue to flower all summer.
The difference in vigor between your butterfly bushes is not unusual. As a broad generalization, the white flowering forms are more vigorous. If they need anything, it would be lime, about 4 pounds per cubic yard of soil. Or, simply work a cupful in around each plant and water well.
Q: I want to plant some fragrant linden trees on my farm. I also wish to raise honeybees. While reading an article on linden it was noted that some lindens were toxic to honeybees. Unfortunately, the article didn't specify which are. I am hoping that you would know and be able to advise me which lindens are known to be nontoxic to honeybees. Also, which linden would grow in zone 7/6. (e-mail)
A: The linden that is toxic to bees is Tilia tomentosa, or silver linden. The American linden--T. americaniais used for honey production, and has a high market value. It is hardy in your area as well as up here in certain locations. There are many cultivars of the American linden that you will find on the market: Boulevard, Dakota, Douglas, Fastigata, Legend, Lincoln, Redmons, Rosehill and Sentry.
Q: We have several hosta plants in 4-inch pots that we have stored inside a shed that is insulated, but not heated. We did not plant these hostas last year because we were not sure where we wanted them. My question is are there any precautions or things that we should do to insure that these plants make it until spring? I realize that it is a little too late to do too much as the winter is almost past. If there is any info you could supply, please do. (Pelican Rapids, Minn., e-mail)
A: Basically keep them moist until they get planted. Try also to keep them dormant until they can get planted. Do this by moving them outside when the snow leaves, but the ground is still frozen. Store them on the north side of your home or garage until you can dig in unfrozen soil. Be sure they are planted where they will get more shade than direct sunlight, and water them in well, initially. Once they start growing, hostas need little care, and certainly no further water. Hostas are a good xeric (low-water-requirement) plant.
Q: While paging through some new garden catalogs, I read that fig trees can be grown in pots, then moved inside for the winter. Will this really work? That is, will the tree actually produce figs? What variety would be best? And what kind of care--fertilizing, "rest" during winter etc.--would it need? (My husband loves fresh figs and would be thrilled to grow his own.
Also in the catalogs, I saw an ad for a product called "Sluggo," which is advertised as an organic slug bait that is nontoxic to pets. The active ingredient is iron phosphate. I'd like to try it, but it's fairly expensive, so I wonder if you've heard any reports on it.
Finally, I should tell you that I'm the person who wrote late last summer with the hornets in the compost pile. You had some spray recommendations, but I finally broke down and called a service, and I'm glad I did. The service guy removed a nest in the pile the size of a softball. I doubt I would have had the nerve! (Bismarck, N.D., e-mail)
A: I have not heard of moving figs inside to get them to produce. I did know an Italian/American gardener when I was living in upstate New York who successfully grew figs that bore fruit by planting them against a wall that faced the sun most of the day. When winter came, he would carefully cut the branches back, and wrap the top part of the plant with water proof paper and shredded newspapers. He would then dig a trench along the side of the trees and lay them down, covering them with topsoil.
I have no experience or data with iron phosphate or the Sluggo you refer to for slug control. I cannot give you any judgement on its effectiveness.
I, too, am glad that you called a service to remove the wasp nest! I have been stung by those characters and the thought of that many being there makes my skin crawl!
Q: Are you familiar with the perennial Hadspen blood astrantia? If so can it be grown here and where can it be purchased? (Fargo, N.D.)
A: I'm unfamiliar with the perennial and four of my plant books know nothing about it either. Perhaps one of our readers will know about it.
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 email@example.com.
Source: Ron Smith (701) 231-8161
Editor: Dean Hulse (701) 231-6136