I'm wondering if I should use landscape fabric under mulch to
control weeds. I really don't want to because I was always under the
impression that it trapped moisture and restricted the growth of
The new landscape fabrics do allow moisture exchange. However, it does present a problem when you want or need to remove it. Shredded mulch will do as good a job of controlling weeds as fabric. Some of the weed seeds that blow into your mulch will sprout regardless of whether you use landscape fabric. You may also want to consider that your mulch will gradually decompose and become compost. If there is fabric underneath the mulch, that compost will not benefit your soil. Another concern is that trees and shrubs may develop shallow roots under landscape fabric, which makes them less drought tolerant in times of dry weather.
Certain weeds that sprout in mulch can be prevented by using a preemergence herbicide. Read labels carefully so you do not damage the plants you want to keep. If you need personal guidance, contact your local Extension office.
Also remember that using an adequate layer of mulch makes it easier to hand pull the few wind blown seeds that do sprout. Check frequently for new sprouts and other garden pests.
Do not use freshly shredded or chipped wood. Fresh, or new, wood will compete with your plants for nitrogen and can release other unwelcome volatiles. The mulch should be composted or aged.