Michigan Gardening To-Do List: September

Northern Sea Oats
Northern Sea Oats

September continues the bountiful harvest of all of that work we put into our gardens over the summer. The nights are cooler, the days shorter, and things are just generally starting to slow down in the garden. Zones 3 and 4 could see a frost this month, so keep an eye on the weather and protect any frost-sensitive plants you’re not quite ready to let go of just yet.

This is also a good time to take stock of this year’s garden, while everything’s fresh in your mind. What worked really well? What didn’t? Which areas of your garden need work, whether it’s soil improvement or structural improvements? Which varieties were absolutely stellar, and which were duds? Should you have planted more of one thing and less of another? It’s a good idea to write all of this down, so when you’re planning next year’s garden, you’ll have these recollections at the ready and will avoid doing things that didn’t work as well for you this time around.

Other than taking stock of this  year’s hits and misses, here’s a quick list of what needs to get done in your garden in September:

Herb/Vegetable Garden

  • Keep watering and weeding.
  • Harvest regularly to keep plants producing well.
  • Deadhead herbs such as basil regularly to keep them productive.
  • Check plants regularly for signs of pest or diseases.
  • Remove any summer veggie plants that are looking ragged or becoming less productive.
  • At least once this month, feed your vegetable plants with a foliar feed of fish emulsion.
  • Sow more fall crops directly into your garden, including mesclun, spinach, mache, radishes, and carrots. If you’re in zones 4 or lower, it’s likely too late to do this unless you’re sowing in a greenhouse, low tunnel, or cold frame.


  • Keep deadheading to keep plants looking their best.
  • Water regularly.
  • Fertilize once a week with a diluted (1/4 strength) solution of fish emulsion.
  • Remove summer annuals that may be looking ragged and replace with fall flowers, such as mums, asters, ornamental kale, or pansies.


  • September is a great time to dig and divide any perennials that look overgrown to you.
  • You can usually get good deals on many plants this month, when garden centers and nurseries start running their “fall planting” sales.


  • You can start planting spring-blooming bulbs, such as tulips, daffodils, hyacinths, muscari, and snowdrops.
  • If squirrels or other wildlife dig up your bulbs, place a section of chicken wire or metal hardware cloth over the area. Pin it down and cover it with mulch. This should protect it from those pesky critters.

Trees and Shrubs

  • Trees and shrubs will need an inch of water per week to stay healthy, either from rain or from the hose.