City Gardener

Today, I returned to volunteer at the University of Minnesota Botanical Conservatory for another shift. It was once again a pleasure to roll up my sleeves and continue the never-ending task of cleaning insect pests off the plants. My assignment was limited to a small area: a bench holding about two dozen plants. Each one had to be inspected for pests, cleaned with soapy water, and sprayed with a solution of essential oils to deter further infestation. While working, I couldn't help but wonder about the efficacy of spraying the plants with clove and spearmint essential oils. Do they really work as well as synthetic pesticides, which are specifically designed to kill insects? How much credible literature supports the use of plant oils as insecticides and repellents? And do they work against all insect pests, or only certain species? A brief search in Google Scholar produced thousands of articles spanning many years, addressing the use of essential oils in agriculture. It's defini...

I didn't know that the cardboard palm - Zamia furfuracea - is a cycad. It isn't a palm tree (don't judge me, I'm not a botanist). But it also doesn't look like the other more familiar types of cycads with their fluted upright palm-like fronds. I didn't know it is said to be the second most commonly cultivated cycad, after Cycas revoluta . I didn't know this plant is unrelated to the common ZZ plant - Zamioculcas zamifolia - although they have a similar appearance. Before today I didn't know any of these things, but now I am happy to have learned them. From the parking lot I walked to the U of M Conservatory greenhouse in near-zero F weather. Stepping into the tropical spaces was a joy of its own. But being able to learn new information and experience new procedures was a compounding factor. Joy squared. During my 3-hour volunteer shift, my initial task was to clean the parasite critters (mealybugs and scale) from the stems and leaves of the cycad, Zami...

Whether in our homes or workplaces, we all have a routine for cleaning things. But often apart from our routine, there are those hard-to-reach places where dust or other bits collect. Over time, the buildup of debris can be a shock when the existence of these neglected spots is finally realized. Today at the U of M Conservatory greenhouse, where I am a volunteer indoor gardener, I spent my 3-hour shift reaching into out-of-the-way spaces to sweep, rinse, or wipe away fallen debris. I focused my efforts on the public area of the conservatory where new guests are more likely to see dusty surfaces that have escaped recent routine maintenance. A similar form of untidiness is the sudden realization that a particular plant has grown immensely since the last time you noticed it. The leaves have overspread the space and blocked much of the sun light for everything below. It is time to prune away the excess. My task for today included pruning the largest plant in the collection, a tree fern nat...

It seems my efforts as a volunteer in the greenhouse often involve cleaning plants that have been infested by damaging insects. I know I've not been singled out for this task. It takes non-stop team effort from everyone on the staff of the University of Minnesota Conservatory to help control pests from overwhelming the plant collections.  The greenhouse staff rightly favors the use of biologic pest control over the use of toxic chemicals. The biologic controls are usually in the form of predatory critters. But the beneficial predators alone are not enough to keep plants healthy indoors. Along with "beneficials," a multi-prong approach is needed. It includes the use of physical removal of pests from the plants - usually scrubbing with soap and water. Another prong is the use of essential oils which are noxious to the pests, the oils are sprayed onto the leaves to deter the pests from spreading. A solution of peppermint and clove oil are commonly used.   My tasks today bega...