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Growing Together: Test your garden IQ

A gardening quiz can be a fun way to learn answers to commonly asked questions. Dave Wallis / The Forum1 / 2
Don Kinzler2 / 2

Quiz time in school usually gave me an upset stomach. But we’ll grade our own papers on today’s gardening quiz, and if you use a No. 2 pencil, the rest of us will look the other way if you make any corrections while we’re checking answers.

A wealth of gardening information can be gathered while pondering questions. As one of my college professors was fond of saying, the following test contains a little something for everyone.


1. Is it all right to cut off the leaves of tulips after they’re done blooming?

2. Is it best to water gardens and flowers in the evening when it’s cool?

3. Because it’s mid-June, should dead tree branches wait until the dormant season to be pruned?

4. Are quackgrass and crabgrass common names for the same grassy weed?

5. Is the main benefit of perennial flowers the fact that once planted, the work is pretty much finished?

6. Does the majority of a tree’s root system go vertically into the ground, or horizontally outward?

7. When fertilizing a tree, is it best to apply the majority of the product closest to the trunk?

8. Will the commonly sold granular herbicide Preen kill small weeds that are growing in perennial flowers?

9. How many times a year should lawns be fertilized?

10. Should lawn clippings be bagged and removed during mowing?

11. Are ants needed on peony buds for the flowers to open properly?

12. Is iron chlorosis a liver ailment?

13. Is the weed spray used on lawns safe to use next to shrubs, flowers and vegetables?


1. No. Leaves should remain on tulips until they are completely yellow/brown and dry because while still green, they produce next year’s flowers and leaves hidden within the bulb. Removing leaves prematurely thwarts next spring’s show.

2. Watering is best done in the morning. Evening and nighttime watering should be avoided if possible, because diseases easily gain a foothold when foliage remains damp during night hours.

3. Most dead branches should be removed anytime they are detected to prevent them from becoming a host to additional problems. To prevent possible spread of disease organisms during the growing season, it’s wise to disinfect the pruning shears between cuts with bleach/water solution.

4. No. Quackgrass is perennial, living year to year and spreading by pearly-white underground rhizomes. Its blade growth is upright. Crabgrass is an annual, germinating each year from seed. It is recognizable by its “goosefoot”-shaped seedheads. Blade growth is squat, hugging the ground more horizontally than upright.

5. Unfortunately, planting perennials with the idea that the work is completed is the gardening equivalent of having a baby and believing the task is finished. Keeping weeds from establishing close to plants is a perennial problem.

6. The majority of a tree’s roots spread outward horizontally instead of vertically. Roots seek the upper layers of soil that contain more oxygen and nutrients than subsoil. Exceptions are tap-rooted species like oak and walnut.

7. Most of the “feeder roots,” which are responsible for nutrient uptake, are located close to a tree’s “drip line” toward the outer edges of the leaf canopy. Roots closest to the trunk are older, woody support roots, less capable of utilizing fertilizer. Applying product in this area is least efficient.

8. No, It won’t kill weeds that are already growing. Preen prevents many types of weed seeds from sprouting and becoming established. It is a great weed preventer, but its mode of action does not kill weeds that are already growing.

9. Regional universities recommend fertilizing twice during the season, approximately Memorial Day and Labor Day.

10. There’s little need to remove lawn clippings unless they lay on the surface like new-mown hay. Allowing lawn clipping to decompose naturally provides nutrients equivalent to one fertilizing per season. Some gardeners bag lawn clipping to create their own compost pile.

11. I couldn’t resist the age-old controversy of whether ants are needed on peony buds. The American Peony Society indicates ants are attracted to the sticky buds, but are neither beneficial nor harmful and are not necessary for flowers to open.

12. No. Just seeing if you’re still paying attention. Iron chlorosis is an iron deficiency with symptoms of yellowing leaves with veins remaining green. Species most susceptible are maple, birch, rose, plum, cotoneaster and mountain ash, among others.

13. Lawn weed spray can be safe, but only if used properly. Most lawn herbicides contain 2,4-D with its familiar aroma. If the chemical is sprayed or allowed to drift onto desirable plants they can be injured or killed. Certain species are more susceptible. Every year my heart sinks when I observe misshapen, deformed leaves of tomatoes, grapes and maples damaged from overspray.

How did you do? Grading is easy. Anytime we talk gardening, we’re all doing A+ work.

Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler’s Greenhouse in Fargo. Tune in to his weekly radio show from 10 to 10:30 a.m. Wednesdays on WDAY Radio 970. Readers can reach him at