August Zone 3

What to do in the garden in August in zone 3

  • Water  August can be hot and dry.  Make sure everything is getting enough water, about an inch per week for most plants and lawn, more in extreme heat and drought.  Tomatoes must have consistent watering to prevent mis-shapen fruit and blossom end rot.  Water in the morning to minimize evaporation.
  • Don’t apply pesticides  During the summer heat, avoid applying pesticides, even insecticidal soaps.  If you must, apply on a cool evening.
  • Feed annuals  Annuals need regular fertilizing for good bloom production, about every 3-4 weeks.  Baskets and containers may require feeding every 2-3 weeks.
  • Raise the blade  If you haven’t done it yet, raise the blade on the lawn mower.  You need to be at 3” by now.  The growth will be slowing down a bit anyway in the summer heat, and a little longer grass shades the soil better to retain moisture.  Your lawn will look much greener and healthier, and require less sprinkling.
  • Prepare for dormancy  Trees and shrubs want to drink heavily for the next couple of months to prepare for winter dormancy.
  • Harvest  Many of your vegetables will be ready for harvest by now.  Early season crops have been coming all along, but beans should be ready this month and tomatoes and peppers coming up soon.
  • Stop fertilizing plants  By mid August discontinue fertilizing perennials and shrubs.  Fertilizing now will encourage new growth that may not be ready for fall freezing temperatures.  Annuals and vegetables can be fertilized right up until frost to keep them fresh and blooming.
  • Fertilize vegetables  Fertilize the vegetable gardens every few weeks with a liquid fertilizer, less often with slow release and organic fertilizer.  Most herbs need little or no fertilizer if the soil is well enriched.
  • Check containers and baskets  Container gardens, hanging baskets and window boxes dry out quickly and need frequent watering.  They will also need to be fertilized regularly.
  • Lawn Repair  When summer starts to cool and the soil is still good and warm, which could be late August or early September, lawn seed or sod will establish quickly.
  • Weed  Keep weeding to prevent a big fall weed crop the competes with your garden plants for water and nutrients.
  • Fertilize the lawn  The grass should be fertilized about every 6 weeks.  If you are due, and it is not too hot and dry, you may be able to make a light application by middle of the month.
  • Plant peonies  Plant, or divide and transplant peonies between the end of August and October.  Remember that peonies prefer not to be disturbed, so divide only if the clump has gotten way too large.


  • Check for grubs  Dead patches of grass may signal grub activity.  If the brown patch will pull up like a loose piece of sod, you probably have grubs.  If the problem is widespread or severe, treat with non toxic milky spore, or grub control chemicals.  Don’t worry about a small or limited problem, your lawn should recover with enough water.
  • Plant fall bloomers By the middle to end of August you should be planting fall blooming annuals or perennials such as asters and fall blooming crocus.
  • Divide  Daylilies, bearded iris, and peonies can be divided by end of August or into September.  Water well a few days ahead of division and again after replanted.  Mulch well.
  • Prune Oak and Walnut  By end of August through October it is safe to prune Oak and Walnut Trees.
  • Relax in the shade  Fall nursery catalogs should be arriving.  Sit in the shade and relax with the pile.
  • Drink water and wear sunscreen!
calendarSharon Dwyer