The Homeowners Column

The Homeowners Column

September garden "to do" list

Photo of Sandra Mason

Sandra Mason
State Master Gardener Coordinator

August has been kind to gardens and gardeners this year. Overall the cooler temperatures and periodic rains have helped our gardens to grow and gardeners to garden.

September is our second chance to wildly work in the garden. This reminder list should help get you started. If the sight of this list makes you shudder, than you need to step away from your garden and slowly put down your pruners. Take a minute to breathe in the last moments of summer.


  • Transplant and divide most perennials.
  • This is the best time to divide peonies. Be sure to have 3-5 eyes per division. Replant so eyes are no more than 2 inches deep.
  • Replant areas with frost tolerant plants such as pansies and flowering kale.
  • Plant mums into well-drained areas. Planting on a slight mound may help to provide proper drainage to get mums through the winter.
  • Prepare houseplants for return trip indoors. Thoroughly rinse leaves and container. Place in halfway house such as a porch or carport.
  • Begin 2-3 month dormancy for amaryllis. Do not water. Place indoors in cool dark place. Dormancy begins once leaves yellow.
  • Purchase spring flowering bulbs for October planting.
  • Discontinue fertilizing roses.


  • Harvest herbs such as sage and oregano by hanging clean stems upside down in dark space.
  • Pot chives, oregano, basil or rosemary for winter use indoors.


  • Mow and water as necessary. Mowing height may be lowered to 2 inches as temperature decreases.
  • Fertilize in early September. This is the most important application of the year.
  • Reseed bare or thin areas with improved cultivars. Consider renting a slit seeder to get seed down into soil of existing lawns.
  • Reduce thatch if more then one half inch by using core aerifiers or vertical mowers.
  • Core aerifiers may be used to reduce soil compaction.
  • Establish turf by seed (best time). Prepare soil properly and get good seed to soil contact. Select turf mixes and blends appropriate to the site and to maintenance practices. Northern Illinois – August 15- September 7; Central Illinois – August 15 – September 15; Southern Illinois – September.


  • Continue harvesting vegetables to keep plants productive.
  • Pumpkins and winter squash should have hard rind before harvesting.
  • Seed bare areas with winter rye or barley for a winter cover crop and to add organic matter to the soil.
  • Plant spinach and other leafy vegetables for late fall harvest.


  • Plant most trees and shrubs. Be sure not to plant too deep. Check for trunk flare. It should be above the soil line.
  • Water trees and shrubs. Plants, especially evergreens, should be well hydrated entering winter.
  • Avoid severe pruning now if possible. Wait until February or March for most trees and shrubs. Spring bloomers such as forsythia and lilac should be pruned right after bloom.
  • Pick bagworms from evergreens if possible. Pesticide sprays are not effective once caterpillars stop feeding. Wait until next year to determine if limbs will releaf. Spray with Bt products mid-late June.


  • If you are planning to plant blueberries, rhododendrons or blue hydrangeas, prepare the soil now for a spring planting. Add sulfur according to soil test to lower pH. Add organic matter such as leaf compost.
  • Add plant debris to compost pile as you clean flower and vegetable areas. Debris will decompose faster if it is shredded or chopped. Also layer with soil or compost.

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