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The ornamental garden in September: plants that provide color in the flower bed & tasks in the autumn garden!

September marks the end of summer and the beginning of the autumnal equinox. Daytime temperatures are still hot, but nighttime temperatures begin to cool. With the change of seasons, it’s time to devote more time to the garden to tackle end-of-summer maintenance tasks and prepare for the cooler weather to come. While you’re at it, look for gaps in the bed that are lacking color and consider how you can make next year’s fall garden even more interesting. Here’s why you should maintain and enrich your ornamental garden in September! Take a look at our tips!

Plants that provide color in the ornamental garden in September

Plants that provide color in the ornamental garden in September

Some gardeners equate their late summer ornamental garden with a “dead zone” where hardly anything seems to bloom. But that doesn’t have to be the case. One simple solution is to plant groups of pansies throughout the bed to provide instant color. For a longer-term and more creative solution to the problem, think outside the box. Besides the usual asters and chrysanthemums, there are many other plants that offer both color and interesting texture. To up the sparkle factor in your late summer garden, you can use some of the following plants:

Leave healthy foliage to protect the crowns of some plants from low temperatures

  • Anise hyssop (Agastache ssp.)
  • Artemisia
  • Beautyberry (Callicarpa)
  • Blue fogflower (Caryopteris)
  • Boltonia
  • Black cohosh (Actaea racemosa)
  • Coral bells (Heuchera)
  • Culver root (Veronicastrum virginicum)
  • Dahlias
  • Goldenrod (Solidago)
  • Globe amaranth (Gomphrena)
  • Common ragwort (Eupatorium)
  • Lamb’s ears (Stachys)
  • Lantana
  • Mexican bush sage (Salvia leucantha)
  • Monkshood (Aconitum)
  • Ornamental peppers
  • Perennial sunflower (Helianthus)
  • Pineapple sage
  • Pink muhly grass (Muhlenbergia)
  • Red spider lily (Lycoris radiata)
  • Russian sage (Perowskia)
  • hellebore (Helenium)
  • Stonecrop (Sedum)
  • Toad lily (Tricyrtis hirta)
  • Turtlehead (Chelone)
  • Zinnias

What tasks should be done in the fall garden

Continue to water shrubs, trees and perennials that need regular moisture

  • Continue to water shrubs, trees and perennials that need regular moisture. If they go into the winter with dry roots, it can mean big problems for trees in the spring. If there is not enough rain, water trees regularly throughout the fall until the ground begins to freeze (usually late October or November). If there is little to no snow cover and little precipitation, you should water your trees 1-2 times per month until they sprout leaves in the spring. Water early in the day when there is no snow or ice near your trees.
  • Keep weeding! Remove anything that looks diseased and DO NOT compost it. If you leave the seed heads, they can also seed themselves. If your garden has room, this is a great advantage. And if not, be on the lookout for seedlings next spring. Replant them in other areas or pot them up to share.

Cut back grasses and sedges in early spring rather than fall


  • Remove foliage from plants that are affected by powdery mildew. This powdery mildew often appears later in the growing season. Many fungal diseases can overwinter in plant debris and cause infections the following year if growing conditions favor the disease. Powdery mildew, for example, often occurs when conditions are cool and moist.
  • Leave healthy foliage to protect the crowns of some plants from low temperatures. The energy of healthy foliage stays in the plant and feeds the roots. What types of perennials should have their foliage retained? Fern fronds should not be removed because they protect the crown. The evergreen foliage of hellebores should not be removed. Perennials with basal crowns (a rosette of leaves connecting the stem to the roots) often die back to the crown. If a perennial produces new basal leaves at the crown, cut off the spent stems but do not disturb the new leaves at the base. Examples of such perennials include coral bells (Heuchera sanguinea), Siberian goutweed (Brunnera macrophylla), Salvia x sylvestris, lungwort (Pulmonaria), black-eyed Susanna (Rudbeckia), purple coneflower (Echinacea), carnation root (Lychnis coronaria), and wild indigo (Baptisia).

The ornamental garden in September - plants that provide color in the flower bed & tasks in the autumn garden.

  • Cut back grasses and sedges in early spring rather than fall to protect the crown in winter and provide habitat for insects, birds, and small mammals. The beautiful colors and textures of grasses and sedges add winter interest to the landscape.
  • Remove annuals that are faded, diseased, or that you know will become “slimy” at the first frost. Impatiens are a good example of annuals that turn black with the first frost.

Rejuvenate your planters by supplementing your summer annuals with fall flowers


  • Rejuvenate your planters by adding fall flowers to your healthiest summer annuals.
  • Bring houseplants indoors before night temperatures drop. Carefully inspect plants for pests such as scale insects, whitefly, mealybugs, spider mites or fungus gnats. Wipe down containers and saucers, including the undersides, to remove cobwebs, dirt and debris. Pay special attention to the undersides of leaves, where pests are most likely to reside.

Divide and plant perennials and bulb flowers.

Ornamental garden in September - Now is an excellent time to divide perennials

September is an excellent time to divide perennials . Most recommendations give 4-6 weeks before the first frost to allow plants to take root. More tender plants need a longer adjustment period.  Although many perennials can be divided in either spring or fall, a general guideline is that spring-blooming perennials should be divided in fall and summer- to fall-blooming perennials should be divided in spring.

Here's why you should maintain and enrich your ornamental garden in September

Fall is also a good time to plant perennials that you can find on sale at the end of the season. However, keep in mind the date of the first frost and the 6-week guideline as described above. September is also a good time to plant bulb flowers that will add spring color to your ornamental garden!

September ornamental garden - remove anything that looks diseased and DO NOT compost it