To control weeds in your garden, late summer and early fall is the best time to make a difference

Late summer and early fall are the best times to control weeds because this period determines how clean and manageable your garden will be the following spring. At this time, weeds are actively growing and spreading seeds, which can lie dormant in the soil for years. For example, a single dandelion can produce hundreds of seeds, while plants like crabgrass can drop thousands. By acting now, gardeners can prevent these seeds from germinating later, reducing the need for spring cleanup. The soil is also still warm, which helps perennial weeds like dandelions absorb herbicides more effectively if used. Additionally, disrupting winter annual weeds, which sprout in late summer and survive the cold as low-lying rosettes, can prevent an early spring weed explosion. This proactive approach saves time and effort in the long run.

The primary goal in late summer and early fall is to stop weeds from producing seeds. Annual weeds, such as crabgrass, purslane, and pigweed, die with the first hard frost, so their main threat is seed spread. Gardeners should slice these weeds off at or just below the soil line using a hoe, which kills them without disturbing deeper soil layers that nourish desired plants. Perennial weeds, like dandelions, field bindweed, and thistles, survive winter by storing energy in deep roots or horizontal underground stems called rhizomes. These must be pulled or dug out completely while the soil is moist to ensure the entire root system is removed. Never leave uprooted perennials on bare soil, as some, like bindweed, can reroot overnight in moist conditions. After working in heavily infested areas, clean tools to avoid spreading root fragments to other parts of the garden.

Late summer and early fall are also the best times to use herbicides on perennial weeds because they begin moving nutrients, including carbohydrates, down into their root systems for winter storage. If herbicides are applied during this period, they are transported deep into the roots, making the treatment far more effective than spring applications. This is particularly useful for stubborn weeds like field bindweed or ground ivy. Organic weed-killing options, such as corn gluten meal, can also be applied in late August to early September to suppress winter annual weeds without synthetic chemicals. However, always follow product instructions carefully to avoid harming desired plants or the environment.

Proper disposal of weeds is critical to prevent them from spreading. Standard backyard composting rarely reaches temperatures high enough to destroy weed seeds or persistent rhizomes, so it is not recommended for weeds with seeds or deep roots. Instead, seal uprooted weeds in a dark plastic bag and place them in direct sunlight for a few weeks to kill all seeds and roots before disposing of them in the trash. Alternatively, send them to a commercial or municipal composting facility where higher temperatures can break them down safely. Never leave cut or uprooted weeds on bare soil, as some species can quickly reroot, worsening the infestation.

Winter annual weeds, such as chickweed, henbit, hairy bittercress, dead nettle, and shepherd’s purse, germinate in late summer and early fall. These weeds survive winter as low-lying rosettes and wake up early in spring to flower before crops are planted. To prevent their growth, gardeners should rake or surface-hoe tiny seedlings sprouting in bare soil during late September and October while they are still small and easy to disrupt. Applying organic controls like corn gluten meal in late August to early September can also suppress these weeds without chemicals. Keeping garden beds covered with mulch or cover crops further prevents winter weeds from taking hold.