The best way to keep weeds from growing up through raised beds is to stop them at the bottom. Before construction begins on the bed, the soil underneath can be treated by a process called soil solarization, which heats soil to a point where many pathogens and weed seeds are destroyed. To solarize soil, cover the bed area with a sheet of heavy, clear plastic, weighted to keep it from blowing away. Keep the plastic in place for at least two months during the hottest part of summer, before removing it to build the bed.
If soil solarization is not a viable strategy, it is still possible to stop weeds before they grow. Before filling a raised bed with soil, line the bottom with landscape fabric, which you can buy at nurseries and garden centers. The fabric is long-lasting and porous, allowing water to pass through while stopping weeds from growing up through it. Though the fabric may be pierced by over-enthusiastic digging, and will eventually break down, it should deter weeds for several years. Though not as long-lasting, newspaper, overlapped and laid several layers thick, can also line the raised bed’s bottom.
If the bottom of the bed was not lined with a weed barrier, or if the barrier has begun to degrade, weeds can be stopped from the top as well. Landscape fabric or newspaper layers can be used between rows of edible or ornamental crops. The layers can be covered with organic mulch, if you wish. Alternately, organic mulch alone, spread to a depth of 2 to 3 inches around plants and between rows, will deter many weeds, as well as helping conserve soil moisture.
Raised bed gardening is a way to make it easier to reach garden beds, overcome poor soil and provide maximum yields of food crops in minimal space. The beds may be raised as little as 6 to 8 inches or as much as several feet, but elevation alone cannot prevent weed seeds from finding their way in. Weeds sometimes work their way up from underlying soil, but may also land on the bed, borne by wind or other means.
Despite soil solarization and weed barriers above and below, a few weeds will persist in sprouting, especially close to planting holes where the soil has been disturbed and barriers pierced to allow plant growth. Weed seeds sometimes arrive on the wind or are present in the soil mix. Beds should be no more than 4 feet wide to make elimination of these weeds possible without stepping on and compacting the soil. Check for weeds regularly. Weeding is most effective when the intrusive plants are young and easy to uproot, but should always be done before they flower and set seed.
Keeping weeds under control isn’t always a question of digging or spraying. A physical barrier (called a mulch) will also help to prevent weed seeds from germinating. This light-excluding layer on the soil surface can be of gravel, bark chippings or easily obtained organic matter.
Blistered hands and aching backs are common complaints after digging or hoeing. Sometimes it is not only the gardener who is damaged. Digging and hoeing can damage the roots of wanted plants, reducing their vigour and encouraging the formation of suckers.
1. Mulch your flower bed
Using Roundup Gel in just one hand, and at the click of a button, you can release the precise amount of gel needed to target the weeds without risk to other nearby plants. So, for crowded borders where you want to protect your beautiful plants, this product is the perfect choice.
2. Use a gel weedkiller such as Roundup Gel
In order to get the best performance from any weedkiller, we would always advise to apply the product when the weather is fair and not to apply in windy conditions. Do not apply if rain is expected within 6 hours of application as this could reduce the efficacy of the product.