Once the calendar flips from August to September, most people get ready for a change from summer to fall. Here in King County, we don’t see the hallmark signs of autumn like leaves changing color or falling until later in the season. Still, the time heading into early fall is a great time to get ahead on your yard care and prepare before wetter, cooler weather settles in. 

Here’s what you can do to prep your garden and yard from September to November, all while reducing your exposure to hazardous materials and ingredients.  

Use the least toxic option for your lawn and garden care 

Chemical yard care products, like fertilizers and weed and bug killers, can cause serious harm to people, animals, and water quality. Natural and organic pesticides are a less toxic option but can still be harmful, especially to beneficial insects, so use them only if necessary.   

Fortify your flower and vegetable gardens.

• Clean out all warm season vegetables and flowers to remove this potential food source for overwintering and diseases. 
• Pull weeds when the ground is moist and before they develop deep roots. 

Protect soil from winter rains with a layer of leaves, compost, or straw mulch. 

Tackle the trees and shrubs. 

• Fall is the best time to plant trees and shrubs because their roots can develop while the soil is moist. 
• Mulch trees and shrubs with leaves or woodchips. Keep it a few inches away from stems and tree trunks. 

Look out for your lawn. 

• Improve struggling areas by aerating, overseeding, and top-dressing with compost. Start by aerating to improve root development and water and air penetration. Next, scatter Northwest-adapted grass seed over thin areas. Finally, rake in a thin layer of compost (about 1/3 inch or 1 cm) to cover the seed and improve the soil. Check out this short video demonstrating how to do this. 
• Plant new lawns in September or October to allow roots to develop during the rainy months. 
• Rake fallen leaves and use them to mulch garden beds or make new compost piles. 

 
When in doubt, ask the Garden Hotline. 

The Garden Hotline is a free, year-round program offered by Seattle Public Utilities, Cascade Water Alliance, and the Haz Waste Program. You can call the Garden Hotline to talk to one of our experts from Monday-Saturday, 9 a.m. to 5 p.m. at 206-633-0224 or email help@gardenhotline.org. 

Visit the Garden Hotline website to learn more and find a live Q&A session to attend to discuss your gardening questions with a professional garden educator.