By Kathleen Cue, Nebraska Extension Horticulture Educator in Dodge County (Week of September 28, 2020)
It may seem like perennials demand lots of our attention, but they are really quite forgiving, with many plants living despite, not because of, our gardening efforts. For their hardiness and beauty, we can ensure they stick around by adhering to a few guidelines.
Digging and Dividing
If your perennial plants didn’t bloom well or they’re crowding their neighbors, fall is an excellent time to divide plants. Some perennials, like ‘Karl Foerester’ feather reed grass, develop woody centers at the crown over time. These areas have lost their vigor and no longer send out growth, despite being dense with plant tissue. Using a sharp spade, dig the entire clump and divide the root system, being sure each division has a crown and roots, discarding the center of the plant to the compost pile. Make sure clumps are at least 6 inches across to ensure good vigor once the division has been planted. Set the divisions in their new location, making sure plants are at the same depth as they were previous to digging. For plants like peonies, this step is critical because plants too deep or too shallow will not bloom again. Cut back foliage by half so the reduced root system's water uptake matches leaf needs. Water the transplants in their new location and mulch to delay ground freeze which allows more time for new roots to develop.
Fertilization
If your soil is clay, then adding fertilizer to your soil is not necessary for the health of your perennials. Clay soils have a high cation exchange capacity (CEC), meaning each clay particle has lots of locations to hold nutrients for good plant nutrition. Sandy soils are a different story because sand does not hold onto nutrients (low CEC) like clay soils, with nutrients leaching away with rainfall. Both sandy and clay soils benefit from mulches as they decompose, adding nutrients and organic matter to the soil.
Fall is For Planting
Fall is a great time to take stock of landscaping "holes". These are areas that had plant loss or could use sprucing up. Perennials planted in fall establish well, when warm soils foster good root growth. Increasingly, gardeners are planting perennials that serve purposes beyond their simple beauty--supplying nectar, pollen and seeds for pollinators and birds, fostering drainage in rain gardens, and serving as traps for blowing snow. Spring flowering bulbs are by their very nature perennials, deriving their survival not from a root system as perennials do, but from underground stems. Tulips and daffodils are classics, but consider adding some of the lesser bulbs like grape hyacinths, glory of the snow, Siberian squill, dogtooth violet, crocus, and summer snowflake, providing food for pollinators when few things are in bloom.
With a few steps, perennial plants will continue to add beauty and joy to our landscapes. Happy Fall!