Weeds are the biggest problem gardeners face. There is no single magic solution for weed control in your landscape, but if you know about weeds, you can control them with simple control systems. First, you need to know some weed basics. Weeds are divided into three main types: annuals, biennials and perennials. Annual weeds grow from seed each year and die before winter. Biennial weeds grow in the first year, set seeds in the second year, and then die. Perennial weeds survive the winter and continue to grow each year, spreading underground and through seed. Complete darkness is the most effective way to control weeds. We spread three to four inches of mulch over newly planted plants and renew it every year with another two to three inches of fresh, sterile mulch. Here’s the key: In winter, the weather eats away at your mulch and new weed seeds will keep sprouting, so if you don’t renew your mulch every spring, you’ll have weeds. Many gardeners line the garden with weed barrier fabric and cover it with mulch. Fabrics themselves are more effective than mulch because they let water and air through to the soil, but block out sunlight. First, they control all three types of weeds by preventing existing weeds and seeds from penetrating the fabric, but eventually new weeds will sprout from seeds dispersed by wind, birds, and grass clippings and enter the bed above the fabric layer. If you don’t have enough mulch to protect from the sun, weeds will grow through your fabric. Using fabric for weed control can have negative consequences if you neglect to prepare the soil before laying the fabric and mulch. The fabric prevents the spread and “settlement” of many plants, thereby scaring off weeds. Fabric can also be a problem if you want to cultivate or change beds. Every time you soil or soil a fabric, you are encouraging weeds to grow. Healthy, happy plants are your best defense against weeds, aggressive competitors that shade the ground. Placing plants in such a way that they crowd each other is very effective for weed control. If you insist on leaving space between plants, weeds will thrive there because they have sunlight and no competition. We believe in ground cover plants such as royal periwinkle, ivy, carpet juniper, and philodendron that act like a blanket, shading the ground and suppressing weed growth. We recommend using a glyphosate-based herbicide such as Roundup (glyphosate) to completely kill all weeds and grasses before laying new beds. If you are growing biennials or perennials, they will multiply; you must destroy them to their deepest roots before plowing. Some weeds, such as weeds, clover, and wild violets, require special herbicides because Roundup won’t kill them. Another important step is to cut the soil along the paths and sides of the beds so that two to three inches of mulch can be added along the edges. Don’t use mulch to allow sunlight to activate weed seeds in the soil. Before mulching, we always clean foundation walls, sidewalks, curbs and other adjacent areas where dirt containing weed seeds could contaminate the new mulch after it has been spread. The last line of defense is “pre-emergence” weed control chemicals such as Treflane, the active ingredient in Prine. These products form a shield that kills emerging weed shoots. We distribute it in the garden before mulching because exposure to air and sunlight reduces its effectiveness. We like to spray the weeds in our gardens rather than uproot them, and if there is any doubt they will uproot them. Pulling weeds can exacerbate the problem by pulling soil and weed seeds out from under the mulch. Deep-rooted weeds such as dandelions and thistles are difficult to uproot. Some weeds, such as walnut grass and wild onion, leave behind a new generation when you pluck them. Spraying is best if you can do it without letting the spray drip onto desired plants. Getting rid of weeds on existing perennials and groundcovers is tricky because most herbicides damage the desired plants. We came up with a solution that we called the “Roundup Glove”. To do this, simply wear rubber gloves under cheap cotton work gloves. Dip your hands in a bucket or bowl of Roundup, squeeze out the excess with your fist to stop dripping, and dampen your fingers with the weed. Everything you touch dies in about a week. Steve Boehme is a landscape architect/installer who specializes in landscape “modernization”. Growing Together is published weekly
Post time: Apr-03-2023