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Growing Together: Test your green thumb IQ with today's gardening quiz

Don Kinzler, Growing Together and Fielding Questions columnist. The Forum1 / 4
Today's gardening quiz answers whether perennials should be dug and divided when in bloom. Forum file photo2 / 4
Tips for controlling apple maggots are provided in today's gardening quiz. Forum file photo3 / 4
Can every flower on a squash vine produce a squash fruit? The answer is provided in today's gardening quiz. Forum file photo4 / 4

FARGO — My how time flies. It’s been more than six months since our last semiannual gardening quiz.

Sharpen a pencil — and keep your eyes on your own paper — as we test our gardening wits.

The following questions can be answered in a few words.


  1. Is crabgrass the wide-bladed, coarse, undesirable grass in our lawns?
  2. If tomatoes fail to produce fruit, could it be because there weren’t enough bees or other pollinators in the area?
  3. After tulips are finished blooming, is it OK to cut back the leaves?
  4. When fertilizing a tree, is it be better to apply the product close to the trunk, or at the outskirts of the tree’s leafy canopy?
  5. Many national chain stores sell bags of lime as a soil additive. Does adding lime help plants grow better in North Dakota and western Minnesota?
  6. Which helps to suppress weeds better, mowing the lawn short or mowing it taller?
  7. Can every blossom on a squash plant potentially bear a squash fruit?
  8. If the tag in a pack of tomato plants lists 95 days to maturity, is that cultivar considered early, midseason or late for gardens in the Upper Midwest?
  9. To control apple maggots that cause brown streaks in fruit, is it necessary to apply insecticides more than once?
  10. When digging and dividing a perennial, is it best to do so when it’s in full bloom so you can see what type you have?


  1. All wide-bladed coarse grasses in the lawn aren’t necessarily crabgrass, but are commonly quackgrass, tall fescue and others. Crabgrass preventers won’t control quackgrass and tall fescue, which are often more prevalent than crabgrass.
  2. Bees aren’t necessary for a plentiful tomato crop, as tomato flowers are primarily pollinated as wind vibrates the blossoms.
  3. No, it’s not wise to remove tulip leaves while they’re still green because after bloom, the foliage replenishes the underground bulb, forming next year’s flower buds and leaves deep within the bulb. Removing leaves before they are brown-crisp can weaken the tulips.
  4. Applying fertilizer next to the tree’s trunk is much less effective, because the “feeder roots” that absorb nutrients from the soil are located closer to the tree’s outskirts. Roots close to the trunk are woody, function as support and are much less able to absorb fertilizer.
  5. No. Lime is an alkaline product useful on acid soils in other regions of the country, but can be dangerous if added to most soils in North Dakota and western Minnesota, which are already alkaline.
  6. Lawn weeds are inhibited best by mowing turf taller at 3 inches. Mowing lawns short depresses grass growth and encourages weeds by giving them greater exposure to sunshine.
  7. No. Squash vines have separate male and female flowers growing on the same plant. Only the female flowers will produce a squash fruit. The male flowers are pollen-producers only.
  8. Days to maturity from transplant date are guidelines depending greatly on warmth, but 95 days is late. Early cultivars are listed as about 45 to 65 days, midseason 65 to 78 days and late types 80 to 110 days.
  9. Yes. Beginning in mid- to late June, insecticides like carbaryl (Sevin), malathion or spinosad must be applied at regular intervals until August, usually seven to 10 days, following label directions. The flies that lay eggs that hatch into apple maggots continue activity throughout much of summer from late June on.
  10. No. Perennials are easily injured if disrupted during their vulnerable blooming stage. Instead, dig and divide perennials during the season opposite their flowering.

Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler’s Greenhouse in Fargo. Readers can reach him at