10 tips for better perennial flowers

In today's "Growing Together" column, Don Kinzler says there are steps you can take to get the most from your flower beds and landscapes.

Giant fleece flower is an easy-to-grow perennial. Michael Vosburg / Forum Photo Editor
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Have you ever wondered if an unfamiliar plant in your flower garden is the new perennial you planted last year or just a weed that grew in its place? There’s an easy way to tell — just pull on it. If it comes out easily, it was your perennial flower. If it remains stubbornly in place, it’s a weed.

Joking aside, perennial flowers are enjoying high popularity, and with good reason. There’s a lot to like about flowers that return each year without replanting. Perennials come in all shapes, sizes, colors and heights, and there’s something for everyone.

Here are 10 tips for getting the most from perennials in flower beds and landscapes.

  1. Create a perennial garden using combinations. Each perennial type has a seasonal window of bloom. Some flower in early summer, like peony, bleeding heart and iris. Others bloom in midsummer, like daylilies, phlox and true lilies. Some flower in fall, like mums and perennial asters. Selecting perennials from each bloom season keeps the flower garden in color all season and creates interest as the garden changes monthly. There isn’t a perennial type that blossoms from spring until fall, though.
    Genti-Blue Campanula is a low-growing perennial that blooms in midsummer. Michael Vosburg / Forum Photo Editor
  2. Build a perennial garden with a backbone of long-lived perennial types. By definition, perennials continue living from year to year, but it doesn’t mean they live indefinitely, and some types are longer-lived than others. Perennials with the longest lives include peony, iris, bleeding heart, gas plant, hosta and daylily. Even though other perennials might have slightly shorter lives, they’re important additions to round out the blooming season.
  3. Locate perennials in their preferred light level, either sunny or shaded. Select carefully when choosing perennials for hot, dry locations or cool, moist sites.
  4. When planning a new perennial bed, first take time to eliminate existing perennial weeds like thistles, quack grass and dandelions. Spending a summer in preparation is time well-spent.
  5. Most perennial flowers thrive in a soil rich in organic material. Add 2 to 3 inches of peat moss or compost and work into the top 6 inches of soil. For perennials already established, circle organic material around each plant and incorporate into the top inches of soil.
  6. Avoid the temptation to make perennial beds appear full immediately after planting. Give each perennial the footprint of space needed as it matures, indicated by the plant’s width on the descriptive tag. Most perennials require two to three years to reach their potential, and they need room to thrive without being crowded.
  7. Perennial flower beds can be low-maintenance, but none are no-maintenance. A preferred way of maintaining a perennial bed, recommended by university research, is to apply shredded bark or similar wood product mulch directly onto the soil without an underlayment of fabric. If the mulch is 5 inches thick, it will block out most weeds. As the mulch in contact with the soil decomposes, it creates a healthy base of organic material, slowly releasing nutrients. Add mulch to the surface as needed. Although many perennials will grow in a landscape mulched with rock, it’s the least favorite and least natural way of maintaining perennials.
  8. Increase impact by planting groups of three or five plants of a kind, instead of scattered individuals.
  9. Roses create a colorful addition to the perennial garden, and many types developed in Canadian breeding programs have increased winter hardiness.
    Canadian-bred roses, such as Campfire, are a colorful addition to the perennial garden. Michael Vosburg / Forum Photo Editor
  10. Weed control is the biggest challenge when growing perennials. There isn’t a magic solution that will remove all weeds while leaving the perennial flowers unharmed. Perennial weeds like thistles can be carefully spot-treated with glyphosate, meticulously avoiding any spray droplet contact with “good” plants, and cardboard shields can help. Grass-specific herbicides can control quack grass. Preen preemergent herbicide reduces annual weed seed germination. Tree seedlings often necessitate hand-pulling when intermingled with perennial plants. Spending a few minutes each day weeding gives the opportunity to observe and enjoy.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at


Don Kinzler column mug.jpg
Don Kinzler, "Growing Together" and "Fielding Questions" columnist.

Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at
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