by Jeff Gillman, associate professor of horticulture at the University of Minnesota, who writes quarterly reports of horticultural research that gardeners can use for this website.
I worry about transgenic plants. To be a little more specific, I’m not one of those people who believe that no genetically modified plant should ever see the light of day, but I do worry that some of the things which we’re releasing into our environment could harm us, or the species around us, if we’re not really, really careful.
One of the transgenic crops with the most potential to cause problems, at least in my mind, is transgenic turfgrass which has been modified to resist herbicide. I worry because I see the potential for grasses such as this to invade the ground where we grow our crops and become superweeds.
Recently I noticed an article by a group of researchers who made tall fescue resistant to a particular group of herbicides. Don’t get me wrong; I don’t think that this is the end of the world or anything, but I hope that these researchers know what they’re doing and that if this crop is ever released (and it might not be – many studies are done just to prove that they can be done), plenty of care is taken to make sure we’re not putting ourselves into a bad position if it escapes cultivation.
That said, on to more important (at least in the short term) things – a few of the great articles published over the last few months.
NEW STUDIES
1. Houseplants that Clean the Air
So, you know those crazy air cleaners that you can buy at Hammacher Schlemmer? Well, it turns out that your house plants can clean the air, as 
well. Twenty-eight house plants were tested for their ability to remove five organic air pollutants, including such things as toluene and terpene. Of the plants tested, the best were English ivy, red flame ivy, wandering Jew, Sprenger’s asparagus fern and wax-plant, but the authors were careful to point out that different plants are better at removing different things, so it’s best to have a variety of houseplants living on your tables and windows.
2. Getting Orchids to Bloom
Having trouble getting your Phalaenopsis or Doritaenopsis orchids to bloom? The problem may be that you’re keeping them too warm. For both of these orchids it’s best to keep temperatures below 79 degrees F. during the day to promote blooming. If temperatures do climb over 79 degrees and stay there for more than 8 hours it could prevent your orchid from flowering, at least until temperatures drop again.
3. Wilt-Free Geraniums?
Researchers in Florida took a look at 61 different geraniums to find out which were most resistant to bacterial wilt. In general, they found that zonal and ivy geraniums don’t have much resistance. Regal geraniums don’t have much resistance either, though the cultivar ‘Elegance Camelot’ shows some promise. But there are a few scented geraniums with resistance, including ‘Snowflake’, ‘Old Fashioned Rose’, ‘Apricot’, ‘Peppermint rose,’ and others. Even though these geraniums may have resistance, if there is a cut on the plant, the disease may be able to overcome the resistance.
4. Mulch Options
Thinking of planting a tree in an urban lot and using mulch to protect it? Be careful what you use. When redbuds and baldcypress were grown in Texas there were distinct advantages to using organic mulches such as pine-bark mulch. However, crushed bricks used as mulch seemed to have a negative effect on the trees. Surprisingly, the researchers found that performing better than either bare soil or bricks as mulch are certain plants – like St. Augustinegrass – grown around trees.
