August Zone 4

What to do in the garden in August in zone 4

  • 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 4 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 mid 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 end of the month.

  • Watch for powdery mildew Powdery mildew usually appears in late summer. Fungicidal sprays can be applied to susceptible plants before it attacks.

  • 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 end of August you should be planting fall blooming annuals. Perennials such as asters can be purchased in bloom for planting but are best planted early in the season. Fall blooming bulbs need to planted right away to bloom in September.

  • 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