August Gardening Tips

“Someone’s sitting in the shade today because someone planted a tree a long time ago.”
~Warren Buffett

The most important job this month is to ENJOY your garden.  This is what it is all about.  Take the time to sit on your special bench (or lie in that hammock) and look around at nature working so hard. 

Trees and Shrubs

  • If you are worried about a dry spell, mulch the soil. Mulch aids water retention so you do not have to be out there all hours with the garden hose.
  • Summer blooming shrubs should be pruned for shape after they have finished flowering.  Remove any dead or diseased branches.
  • Apply fertilizer until mid-August.  After then, fertilize with lower levels of nitrogen and higher levels of phosphorus and potassium.
  • You do not want to promote new top growth that will not have a chance to harden off before winter.
  • Keep inspecting for pests. There are many of them out there.


  • Cut back annuals early in August to encourage re-blooming.  Prune some of your favourite flowers to dry for future arrangements.


  • Take a few minutes to cut off the old dead flowers on your perennial plants. A little time spent on grooming the plants will make a big difference in the overall appearance of the garden. By removing the spent flowers, the plants will not go into the seed producing stage and should continue to flower longer into the season.
  • Begin to stake the tall, autumn flowering varieties such as Joe Pye Weed (Eupatorium).


  • Prune your hybrid roses in late August to promote the most fall blossoms. Remove about a third of the vigorous growth. Any stems that cross each other should be removed, as well as those that are in the center of the plant. Weak, spindly canes and any damaged by black spot fungus should be removed.
  • Maintain a spraying schedule to control insects and disease. Spray every two weeks with a fungicide and insectide.


  • Now is the time to start your fall and winter vegetables. Plant starters or seeds of green onions, carrots, beets, lettuce, spinach, radishes, and winter cauliflower directly into the garden early this month.
  • Enjoy the harvest of your homegrown fruits, vegetables and herbs!


  • Contrary to popular belief, a brown lawn isn’t necessarily a dead lawn. Grasses go dormant in times of drought, but will quickly return to life with the fall rains.
  • If a lush green lawn is important to you, and you don’t mind mowing, water it regularly, and deeply. If a water shortage is expected, or you hate tending to grass, you may choose to just let your lawn go dormant, and water it as seldom as once a month.
  • Raise the cutting height of the mower to 3”. Taller grass cools the roots and helps to keep the moisture in the soil longer.

Container Plants

  • Be sure to check the hanging baskets and container grown plants every day during hot weather and about every second day on moderate summer days. Don’t just check the surface… Push your finger an inch or two into the soil to be sure there is adequate moisture below throughout the root area.
  • Water your containers thoroughly each time you water, but be careful not to overwater them.
  • Continue to fertilize weekly to keep your annuals blooming.  Remove any spent flowers to prevent the plant from beginning the seed producing stage. The annuals should continue to flower longer into the season.


  • Grub problems in the soil? Beneficial nematodes are microscopic worms that seek out and destroy grubs. These natural predators should be applied in spring & early fall.
  • Keep the weeds pulled, before they have a chance to flower and go to seed again. Otherwise, you will be fighting newly germinated weed seeds for the next several years. Weeds in the garden are harmful because they rob your plants of water and nutrients, harbour insects and diseases, and, on occasion grow tall enough to shade your flowers and plants.
  • Change the water in your bird bath regularly, and keep it filled. Standing water is less healthy for the birds, and may become a breeding ground for mosquito larvae.
  • Continue to watch for insect, slug and snail, or disease damage throughout the garden, and take the necessary steps to control the problem.

Enjoy your garden!

Feel free to contact Dufferin Garden Centre if you have any plant or garden issues.