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Garden To-Do List for September

Written by Rhonda Ferree, retired horticulture educator

If you are like me, your gardens did not develop exactly as you had planned in the spring. I have more weeds than I usually do in early fall. Parts of my lawn has too much crabgrass and some plants simply do not like their location in the garden. Now is a good time to assess this year's garden successes and challenges and begin planning for next year.

If you have a vegetable garden, continue harvesting vegetables to keep plants productive.

Pumpkins and winter squash should have a hard rind before harvesting. Seed bare areas with winter rye or barley for a winter cover crop. Spinach and other leafy crops can be planted now for a fall crop. Plant garlic in late September for harvest next August.

If your vegetable garden had a lot of disease this year from our wet spring and summer, be sure to clean it up carefully. Good sanitation will help remove some of the disease pathogen so it won't infect next year's plants. It's also a good idea to rotate plants to another location every 2-3 years.

Fall is the best time to do many lawn care activities. Continue to mow the lawn at a 2 inch height and water as necessary. Fertilize in early September. This is the most important application of the year. Reseed bare or thin areas with improved, disease-resistant cultivars. Consider renting a slit seeder to get seed down into soil of existing lawns. Reduce thatch if more than one half inch by using core aerifiers or vertical mowers.

As the temperature begins to cool, it is a good time to renovate old flower beds. Transplant and divide perennials, including peonies. Be sure to have 3-5 eyes on the peony and replant so eyes are no more than 2 inches deep. Plant mums into well-drained garden areas, planting on a slight mound to provide proper drainage that assures mums make it through the winter. Purchase spring flowering bulbs for October planting. Discontinue rose fertilization and pruning.

If you enjoy taking houseplants outside in the summer, prepare them now for their return trip indoors. Scout for insects. Thoroughly rinse leaves and container. Move to a sheltered area and acclimate slowly back indoors.

Fall is the best time to plant most trees and shrubs. Be sure not to plant too deep. Trunk flare should be visible after planting. Water new plants thoroughly. Add supplemental water to all trees and shrubs, if the soil is dry. Plants, especially evergreens, should be well hydrated entering winter. Wait to fertilize or prune trees and shrubs until after leaf fall. Continue to pick bagworms from evergreens since pesticide sprays are not effective at this time.

Most of all, enjoy time outdoors this fall with your family. Gardening is a great family activity.



As horticulture educator, Rhonda Ferree inspired citizens in local communities to grow their own food and improve their home landscapes. She focused on high quality, impactful programs that taught homeowners how to create energy-efficient landscapes using sustainable practices that increase property values and help the environment.

After 30 years with University of Illinois Extension, Rhonda retired in 2018. She continues to share her passion for horticulture related topics as “Retro Rhonda” on social media.

ILRiverHort is a blog that helps people connect to nature and grow.