The Department of Primary Industries and Regional Development release a monthly guide to animal and plant pests, diseases and weeds. The July edition of Backyard Buddies focuses on preventing weeds by using mulch in your garden.
Winter rains are building up moisture levels within the soil; aiding absorption of the nutrients and minerals needed to ensure a healthy plant. Weed seeds are also benefiting from this rain as it helps to provide the optimal conditions for weed germination.
The secret to successful and cost-effective weed control is to strike early, and nothing is earlier than prevention. So it’s important to implement weed management practices in your garden and understand the importance of using clean mulch from a reputable source.
Mulch is commonly used as a protective layer to maintain soil moisture by minimising evaporation. Mulch also prevents weeds by limiting the light required for weed establishment. However, contaminated mulch and the incorrect use of mulch can introduce new weeds into your garden or encourage existing weeds to germinate.
Ask questions of mulch suppliers or retailers to help avoid purchasing mulch contaminated with weed seeds. Mulch that has not reached the optimal temperature required to kill most weed seeds, is not frequently turned or is left uncovered, poses a risk of weed contamination.
Composted mulch or mulch containing large quantities of plant debris and soil are not effective at weed suppression. These act more like a soil they can compact and retain water; providing the perfect conditions for weeds to germinate and prosper.
If looking to suppress weeds, choose coarser mulch. This is commonly made from chunks of wood or bark, and applied up to 4 inches deep.
You can also help protect your garden and our State by reporting suspicious or unusual weeds that pop up after fertilising or applying mulch to the Department of Primary Industries and Regional
Development (Previously the Department of Agriculture and Food WA) using our free mobile app MyWeedWatcher, or report via the department’s Pest and Disease Information Service by calling 1800 084 881 or email firstname.lastname@example.org.