Perennial Plant Care In Seasons One & Two

By David Salman, Founder of High Country Gardens

Perennial plants can be planted anytime the soil is not frozen. But in regions with very hot summers, planting is best accomplished in late fall through early to mid-spring. This allows plants 6-8 weeks to establish roots before the heat of summer brings growth to a stop.

I prefer transplanting smaller pots of perennials, especially native species. These young plants typically have excellent vegetative vigor that allows them to get off to a fast start. Many native species resent being grown in pots long enough to get them well established in "gallons." It's better to let natives do their growing in the ground. I avoid old, root-bound "gallon" plants like the plague. These plants often re-establish slowly. Smaller potted perennials usually catch-up to and out grow "gallons" by the end of the first growing season.

Watering new transplants regularly the first growing season with Liquid Seaweed and SuperThrive is another essential step necessary for successful transplanting. Beyond watering, and protection from pests, new transplants don't need much additional care that first spring/summer growing season. But don't forget to water during the winter when the soil isn't frozen. A deep watering every few weeks is sufficient through the spring thaw.

As summer becomes a memory, mid- to late fall is the time to fertilize. This is the last chore needed for the year. A high quality organic fertilizer like Yum Yum Mix feeds the soil and its microbial population, ensuring that an ample supply of beneficial nutrients are available for the roots to absorb.

Lacking true woody tissue, herbaceous perennials comprise a large group of flowering plants that behave in a similar manner to deciduous trees and shrubs. With the onset of fall and frost, these plants lose their leaves (and stems), remaining dormant as a cold-hardy root and crown (junction between stem and root). Though there are also evergreen perennials, which retain their foliage and stems through the winter, the vast majority of our showiest cold-hardy perennials are deciduous.

The second growing season is when the fun starts. Your perennials grow rapidly and flower abundantly. It's astounding how much larger perennials are their second growing season.

Injurious Insects and Weeding

Spring also means watching for aphids and weeds. Aphids love the succulent early season growth of perennials. A strong stream of water will wash them off. Insecticidal soap is also effective, but only when applied as the aphids first appear. Spring also brings an explosion of early weeds. Weeding now prevents competition with your perennials and prevents the weeds from maturing and releasing seeds.

Grooming

After a good winter chilling, mid-spring is the time to groom perennials by removing last year's dead stems and foliage. Fertilize now if you forgot to do it last fall.

Taller growing varieties, such as Salvia pitcheri 'Grandiflora', Perovskia atriplicifolia (Russian Sage), Helianthus maximiliana 'Lemon Yellow' (Maximilian's Sunflower), and the many varieties of Agastache, will benefit from early season pinching of their leafy shoots. This thickens the stems and encourages huskier plants that will bloom more heavily and stand up straighter without support.

Older plants of Monarda, Achillea, Phlox paniculata, Aster, Iris and Chrysanthemum, and other clump-forming genera that have been growing for 4 or more seasons and look a little tired will enjoy being divided and replanted. Lift the entire clump of emerging shoots and cut it into smaller pieces, discarding any dead stems and roots in the center. For plants that like rich soils, add ample organic matter and soil minerals before re-planting.

Perennials with tap roots or woody crowns (like Agastache, Asclepias, Lavandula, Hymenoxys) do not need to be divided.

Watering and More Grooming

As the season progresses, faded flowers can be "deadheaded."

Strong new growth indicates that the soil is warming up and the days are getting longer. Water deeply but as infrequently as possible. Frequent watering trains shallow roots and creates thirsty plants. Watch carefully for drooping foliage or a grayish cast to the leaf color as an indication that plants need irrigation.

As the season progresses, faded flowers can be "deadheaded." This encourages repeat blooming in some species or simply neatens up the out-of-flower plants. If re-seeding is to be encouraged leave some or all of the old flowers or flower spikes on the plants to let seeds ripen and drop to the soil. Groundcover plants (especially spring blooming species like Aubrieta, Alyssum and Cerastium) benefit from "deadheading." This encourages the plants to put on more leafy growth giving them a dense, solid look for the remainder of the growing season.

Perennial plantings are a satisfying, colorful, and low-maintenance way to beautify your landscape. So don't forget to take time to sit in your garden when the chores are done, to enjoy the beauty of all your efforts.