Herbaceous perennials are a great addition to any garden and come in many colors, sizes, shapes and growth habits.
They grow back every year as opposed to annuals, which only last one growing season. Examples of perennials include black-eyed Susans, daylilies, hostas and phlox. With the exception of evergreen perennials, the top parts of the plants die back to the ground each fall while the crowns and the roots continue to live and regenerate new growth each spring. Perennials have many uses and can be grown in the sun or shade, in containers, as groundcovers and a variety of other situations.
Autumn is the best time of the year to plant perennials. Their root systems will continue to grow and develop during winter allowing them to become established. The plants will then be able to withstand the hot, dry weather the following summer.
Proper soil preparation is essential to planting perennials. Add organic matter, such as humus, peat moss or compost which provides nutrients to the plants, retains moisture and aerates the soil. Apply at least two inches of these materials to the soil and thoroughly till them in 8 to 10 inches deep. Add an all-purpose complete fertilizer, such as 10-10-10, at the rate of one pound per 1,000 square feet and work it into the soil.
Perennials can be started from seed; however, most gardeners prefer buying transplants since they have already grown to a size ready for planting.
Plant them no deeper than the top of the root ball, press the soil firmly around it and then water. As they are becoming established, keep the soil moist and cover the soil with a one- to two-inch layer of fine textured organic mulch such as pine bark or pine straw.
Once established, perennials will occasionally need some maintenance. Proper watering, fertilizing, mulching and pruning are all necessary to keep the plants healthy and attractive.
Many perennials will need to be divided every few years to control their size and quantity, and improve the overall health of the plants. Plantings that are crowded have less vigorous growth and do not bloom as much as well tended plants. The best time to divide perennials is in the fall when they have finished blooming. Reduced flowering and vigor, dead stems, compacted roots and a general unhealthy appearance are signs they need to be divided.
There are several methods of dividing perennials. Those with a fibrous root system, like phlox and salvia, should have sections of the root mass separated with a pitchfork or shovel. Then pull the large clumps apart to get the individual sections with growing points. Hostas can be divided by lifting the entire colony and then pulling the individual clumps apart by hand. Perennials with rhizomes, like irises and cannas, must be dug out, washed off and then cut by hand. Each section of the root must have an eye where the foliage grows. Spreading perennials, like thrift and candytuft, can often be divided into large clumps where each can be planted separately.
Perennials, if properly planted and maintained, will provide beauty for years to come. No garden would be complete without them.
Timothy Daly is an Agricultural and Natural Resource Extension Agent with Gwinnett County. He can be contacted at 678-377-4010 or firstname.lastname@example.org.