During the years my wife, Mary, and I operated our garden center, I always smiled when customers mentioned they wanted to plant perennials to eliminate the work involved in flower gardening.
Longtime area horticulturist Neal Holland, who passed away recently, was fond of saying that planting perennials to eliminate work is like believing the work is done once a baby is born.
Perennials do require maintenance, such as weed control. Dandelions, quackgrass, thistles and other perennial weeds make themselves right at home, nestling themselves safely in the crowns of desirable perennials.
It doesn’t matter that perennials aren’t work-free. They’re delightful, and form the backbone of most homeyard flower gardens. Many are flexible enough to use in landscapes mingled with shrubs, in combinations with annual flowers or in beds strictly devoted to perennial types.
Here are some age-old tips for success with perennial flowers:
- A perennial that blooms from spring until fall hasn’t been created. Instead, each perennial type blooms during a specific part of the growing season — usually two to six weeks.
- For continuous flowering in a perennial garden, combine types from each blooming season, so something is always in blossom. The ever-changing scene is attractive through the season.
- When planning a new perennial flower bed, take time to eliminate perennial weeds and grasses first. Digging and roto-tilling rarely eliminate deep-rooted weeds like thistles or quackgrass that can regenerate from a tiny missed rhizome sprig. Spray with glyphosate, wait 10 days before tilling, then wait several more weeks and respray weeds that reappear. A few weeks of patience can save years of weedy heartache.
- Most perennials thrive in a soil rich in organic material. Add 3 inches of peatmoss, compost or manure over the bed and work into the top 6 inches of soil. Organics can, and should, be added around established perennials.
- Most perennials require well-drained soil, rather than heavy, soggy soil. Mounding the bed, even slightly, helps divert excess water.
- Avoid the temptation to make perennial beds appear full immediately after planting. Follow spacing guidelines on plant tags, giving each plant the footprint needed for development. Most perennials require two to three years to reach their potential.
- If new perennial flower beds look sparse, interplant with annual flowers for the first year or two. Even established perennial beds benefit from adding the season-long color of annuals.
- Flower beds can be low-maintenance, but none are no-maintenance.
- Weed control is definitely the biggest challenge. Spend a few minutes each day weeding, which also gives the chance to observe and enjoy.
- There isn’t a magic solution that will remove all weeds while leaving the perennial flowers unharmed, other than a hoe. Perennial weeds like thistles can be carefully spot-treated with glyphosate. Grass-specific herbicides can control quackgrass. Preen pre-emergent herbicide reduces annual weed seed germination. And keep the hoe handy.
- Perennial beds can be maintained by cleanly cultivating soil or by applying mulch underlain with weed barrier fabric.
- Currently, the 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 particles in close contact with soil decompose, they create a healthy base of organic material, slowly releasing nutrients. Add mulch as needed.
- Although perennials will grow in a landscape mulched with rock, it’s the least favorite and least natural way of maintaining perennials.
- Must-haves in perennial gardens include peony, iris, daylily, phlox, hosta, lily and rose, plus fall-blooming chrysanthemum and aster. Scores of other perennial types, available at locally owned garden centers, can be added to this list of basic necessities.
Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler’s Greenhouse in Fargo. Readers can reach him at firstname.lastname@example.org.