Landscape fabrics are marketed as an easy solution for weeds in garden beds but ultimately may not be worth it. (Chicago Botanic Garden)

I have some large beds of trees and shrubs in my garden, and the weeds have been very difficult to keep up with this year. Will installing a weed barrier fabric be worthwhile?

Weeds have been a particularly big challenge for gardeners to keep up with this year. The rainy spring really got them going, and they still are in many gardens. Gardeners who were not routinely pulling weeds often found their beds overrun with them.

Landscape fabrics are marketed as an easy solution for weeds in garden beds but, in my opinion, the fabrics are not worth using for this purpose. They are sold in rolls of different widths and lengths and are designed to be installed over the surface of the soil and then covered with mulch or gravel. The landscape fabric needs to be permeable to water and air for proper plant growth in the bed. Solid plastic covers should never be used where desirable plants are growing, as they prevent water and air from penetrating the soil, and plants roots need air and water.

In order to use a weed fabric in your beds, you will first need to remove all the large weeds that would prevent the fabric from lying flat on the ground. Ensure that the ground is relatively smooth, as any clods of soil will create lumps in the fabric and be harder to cover with mulch. You will need to cut the landscape fabric to fit around the existing shrubs and then cut slits in the fabric to accommodate any future plantings. In some situations, you may want to use landscape staples to pin the fabric down to help keep it from folding up and poking through the top layer of mulch.

In the short term, by using the fabric, you should get some weed suppression in your beds. Weeds will poke through any openings you left or created in the fabric, though. Organic matter will build up over time above the landscape fabric — as the mulch decomposes — and weeds will start to grow above the fabric. These weeds will be easy to pull but you still will need to weed the bed. The fabric will become visible and unsightly if the mulch decomposes and is not replenished.

The Chicago Botanic Garden uses weed control fabrics in the production nursery to cover gravel areas and suppress weeds in areas used for container growing. The regular watering that container plants need creates great weed growing conditions, and combined with the difficulty in pulling weeds between the pots, weed control fabrics save a lot of work. They are taken up at the end of the season when the containers are put into winter storage.

I think it is best to continue with hand weeding your bed and skip a landscape fabric. There are pre-emergent herbicides that could be applied to your shrub beds that work by preventing the germination of weed seeds but will not control perennial weeds. These products also need to be used very carefully to avoid damaging desirable plants, thus, I do not use them in my home garden.

Tim Johnson is director of horticulture for the Chicago Botanic Garden in Glencoe.

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