MMG September 2020

April is a horticulturist, retired from the Chicago Botanic Garden. She shares monthly gardening tips and would love to help you out with plant and gardening questions. Just send her an email and she will get back to you.


Typically, September is a transition month between Summer and Fall. Time to start to prepare for the colder weather. Transplanting of Perennials, Trees and Shrubs is good now since they aren’t battling the heat.

  1. Perennials—Stop trimming and fertilizing all perennials. Divide and transplant perennials to fill garden areas giving the roots time to develop before Winter. Cut back Perennials that have finished blooming or are diseased.
  2. Annuals—Continue to fertilize and deadhead annual plants. Collect seeds for next season or can disburse seed onto soil to reseed next year.
  3. Bulbs—Dig and store tender bulbs before freezing temperatures. Buy and plant Spring bulbs.
  4. Seed Saving—Start collecting seed for next year’s planting.
  5. Lawn Care—Best time to rejuvenate your lawn. Fertilize, core—aerate and reseed early in September before October. Apply broadleaf weed control, but not on newly seeded grass. Adjust mower level higher.
  6. Vegetable Garden—Harvest remaining summer vegetables before freeze, except cool season vegetables. Dig potatoes from late September and October when leaves die. Harvest winter squash and pumpkins in late September. Remove diseased tomato, potato and squash leaves to prevent disease (*Not in compost but bag up and discard)
  7. Trees and Shrubs—Great time to plant Trees and Shrubs. Transplant fertilizer on newly plantings only to promote growth. Stop fertilizing all other Trees and Shrubs to permit this year’s growth to harden off before Winter. Keep watering all trees and shrubs to prepare for Winter season.
  8. Fruit Care—Harvest raspberry and after harvest prune canes to ground level and destroy canes. Check apple and fruit trees for disease problems. Remove dead branches, but not live branches.
  9. Roses—Last time to fertilize Roses. Stop cutting roses and let them form hips to prepare them for Winter. Remove dead canes only, but not live canes yet.
  10. Garden Evaluating— Look over your garden at successes and failures. Start redesigning beds or plants for next season. Start cuttings before any freezes and decide which plants to overwinter indoors.