This summer has been too wet for some gardeners and too dry for others. Each brings its own set of challenges, from implementing water restrictions, pruning back lush growth, increasing air circulation to reducing excessive moisture and disease. September is a month of renewal, and I hope it brings rain to those who need it and time to dry out to others.
In zone 7, September is the tail end of the time to divide German Bearded Iris. This must be done every 3-5 years and no later than a month before the first frost. Remember, those living in zone 6 have a first frost window of October 5th-15th while those gardening in zone 7a have a first frost window of October 15th-25th, with zone 7b extending into early November. Dividing is a time of renewal, a time to trim off rotted and damaged portions of the Iris rhizome. Replant just the roots leaving the modified stems, aka rhizomes, atop the soil surface, taking care not to cover them with mulch. Cut back the foliage to 6 inches in a fan shape and water well until established.
This is the best time of year to divide plants such as daylilies, hostas, peonies, and other clump-forming perennial plants, so they have time to become established before winter.
With the first frost a month or so away, cuttings can be taken off cold-tender summer annuals such as geraniums, begonias, coleus and impatiens to root, grow and enjoy indoors.
I also bring in and store the amaryllis bulb I have been growing since last Christmas. I put the bulb in a cool dry place allowing the foliage to die back naturally. I then removed the dried foliage and excess soil before putting the bulb in a brown paper bag and placing it in the refrigerator’s crisper for a minimum of 6 weeks. Remember to store apples in a different location to prevent the ethylene gas they naturally release from killing the Amaryllis bulb. Around Thanksgiving, plant the bulb by wiggling it into fresh soil before watering well to initiate the growth of a new blossom.
In the vegetable garden, the list of what can be planted is diminishing as the days grow shorter and the temperature falls. Greens such as lettuce, spinach, mustard and Swiss chard can be sown along with beets, kale, kohlrabi, radish and turnips until mid-September in zone 6 and 7a while those in zone 7b can transplant broccoli and cabbage until then. Take the time to add compost and other organic materials to the soil before planting.
Fall is the time to plant grass, trees, shrubs, bulbs, perennials and pansies. September is the perfect time to renovate the lawn, or just aerate and over seed with cool-season grasses. As noted above, transplant or divide perennials now while trees and shrubs can be planted until the ground truly freezes or the cold winter weather sets in. Always think about the mature height and width of a plant when siting it in the landscape. Remember to keep an air space of 2 feet away from the house when installing a foundation planting to prevent plants from trapping damaging moisture near the building.
While the garden is still thriving, consider which plants you can collect seeds from to store in the refrigerator for use next season. They cannot be hybrids, or the seed will not grow true to form. Learning which plants are and which are not a hybrid lies in the lists, notes, old order forms or sketches you made last spring, or it might be in the pile of seed envelopes you saved — take a look! I enjoy sharing the seeds from my fuchsia-colored 4 O’clocks, Mirabilis jalapa. I also save the black shiny seeds from blackberry lilies, Iris domestica, and seeds from the Hyacinth bean, Dolichos lablab, to share with others. I thought I was an astute seed saver, but I recently ate some humble pie when I discovered I had failed to fully dry out last year’s 4 O’clock seeds — upon opening the container, I discovered it was filled with mold. "Haste makes waste" is proven once again; always allow plenty of time for seeds to fully dry before storing them for any amount of time. Don’t forget to label them, too! Playing “Name that Seed” is always a challenge…
Speaking of challenges, together let us strive to include a few Virginia-native plants in our plan this fall and invigorate the soil with ¼” of compost, worm castings ( vermicompost), or other organic material in our gardens. These two steps will do wonders for our gardens and also the environment.
Happy Gardening!
-Peggy Singlemann, Director of Park Operations and Horticulture at Maymont